Positron-annihilation study of compensation defects in InP

Positron-annihilation lifetime and positron-annihilation Doppler-broadening (PADB) spectroscopies have been employed to investigate the formation of vacancy-type compensation defects in n-type undoped liquid encapsulated Czochrolski grown InP, which undergoes conduction-type conversions under high temperature annealing. N-type InP becomes p-type semiconducting by short time annealing at 700°C, and then turns into n-type again after further annealing but with a much higher resistivity. Long time annealing at 950°C makes the material semi-insulating. Positron lifetime measurements show that the positron average lifetime τ av increases from 245 ps to a higher value of 247 ps for the first n-type to p-type conversion and decreases to 240 ps for the ensuing p-type to n-type conversion. The value of τ av increases slightly to 242 ps upon further annealing and attains a value of 250 ps under 90 h annealing at 950°C. These results together with those of PADB measurements are explained by the model proposed in our previous study. The correlation between the characteristics of positron annihilation and the conversions of conduction type indicates that the formation of vacancy-type defects and the progressive variation of their concentrations during annealing are related to the electrical properties of the bulk InP material. © 2002 American Institute of Physics.published_or_final_versio

EL2 deep-level transient study in semi-insulating GaAs using positron-lifetime spectroscopy

Positron lifetime measurements performed on Au/GaAs samples at room temperature with an applied square-wave ac bias show a frequency dependent interlace related lifetime intensity that peaks around 0.4 Hz. The observation is explained by the ionization of the deep-donor level EL2 to EL2+ in the GaAs region adjacent to the Au/GaAs interface, causing a transient electric field to be experienced by positrons drifting towards the interface. Without resorting to temperature scanning or any Arrhenius plot the EL2 donor level is found to be located 0.80±0.01±0.05 eV below the conduction-band minimum, where the first error estimate is statistical and the second systematic. The result suggests positron annihilation may, in some instances, act as an alternative to capacitance transient spectroscopies in characterizing deep levels in both semiconductors and semi-insulators.published_or_final_versio

Study of DX center in Cd0.8Zn0.2Te:CI by positron annihilation

Variable energy positron beam and positron annihilation lifetime experiments have been carried out to study the DX center in Cd0.8Zn0.2Te:Cl at 50 K. A short positron effective diffusion length of 275±25 Å and a large intensity of 79.0%±0.3% for the long lifetime component indicate a strong trapping effect at DX centers. A trapping rate of κ=1.53±0.05×109 s-1 and a positron lifetime of 335±2 ps at the DX center were obtained. The concentration of DX centers is found to be 5.9 ±0.7×1016 cm-3, which is in good agreement with the results obtained using Hall effect and thermo-electric effect measurements. © 1998 American Institute of Physics.published_or_final_versio

Photoluminescence and lasing characteristics of single nonpolar GaN microwires

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Video Saliency Detection Using Object Proposals

In this paper, we introduce a novel approach to identify salient object regions in videos via object proposals. The core idea is to solve the saliency detection problem by ranking and selecting the salient proposals based on object-level saliency cues. Object proposals offer a more complete and high-level representation, which naturally caters to the needs of salient object detection. As well as introducing this novel solution for video salient object detection, we reorganize various discriminative saliency cues and traditional saliency assumptions on object proposals. With object candidates, a proposal ranking and voting scheme, based on various object-level saliency cues, is designed to screen out nonsalient parts, select salient object regions, and to infer an initial saliency estimate. Then a saliency optimization process that considers temporal consistency and appearance differences between salient and nonsalient regions is used to refine the initial saliency estimates. Our experiments on public datasets (SegTrackV2, Freiburg-Berkeley Motion Segmentation Dataset, and Densely Annotated Video Segmentation) validate the effectiveness, and the proposed method produces significant improvements over state-of-the-art algorithms

The role of regulatory B cells on hepatocellular carcinoma progression

Poster PresentationCongress Theme: Translating Discoveries into Prevention and CuresPURPOSE: Regulatory B cells (Bregs) play important roles in autoimmune diseases, but their function in hepatocellular carcinoma (HCC) progression remains unclear. This study attempted to unveil the role of Bregs on HCC progression. EXPERIMENTAL DESIGN: This study examined the distribution of intrahepatic B cells and circulating Bregs population at the level of phenotypes as well as functionality in HCC patients. The mechanisms of Bregs regulating liver tumor cells were further explored in a series of in vitro and in vivo functional studies. RESULTS: The percentage of B cells at tumor margin region was significantly higher than that in tumor or non-tumor region. Increased intrahepatic B cells at tumor margin were positively associated with tumor invasive features and more tumor recurrence. Besides, HCC patients had a significant higher percentage of circulating Bregs than healthy people. Increased circulating Bregs were positively correlated with advanced tumor staging, tumor multiplicity and venous infiltration. Next, our in vivo study firstly revealed that human Bregs promoted HCC tumor growth independent of Tregs in SCID mice. The migration of Bregs into tumor in mice was further confirmed by in vivo imaging and histology. Finally, the molecular mechanism of Bregs promoted proliferation and migration of HCC cells was proved by direct cell-cell interaction via CD40/CD154 signaling in vitro. Coculture of Bregs and HCC cells induced CD40/CD154-dependent cytokines secretion. CONCLUSION: Human Bregs promoted HCC growth and invasiveness by interacting with HCC tumor cells through CD40/CD154 signaling pathway. Bregs might be both a prognostic marker and a therapeutic target for HCC.published_or_final_versio

Interferon-gamma Inducible Protein 10 up-regulated by acute-phase graft injury induced late-phase cisplatin resistance after liver transplantation

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Intercultural New Media Studies: The Next Frontier in intercultural Communication

New media (ICT\u27s) are transforming communication across cultures. Despite this revolution in cross cultural contact, communication researchers have largely ignored the impact of new media on intercultural communication. This groundbreaking article defines the parameters of a new field of inquiry called Intercultural New Media Studies (INMS), which explores the intersection between ICT\u27s and intercultural communication. Composed of two research areas—(1) new media and intercultural communication theory and (2) culture and new media—INMS investigates new digital theories of intercultural contact as well as refines and expands twentieth-century intercultural communication theories, examining their salience in a digital world. INMS promises to increase our understanding of intercultural communication in a new media age and is the next frontier in intercultural communication

The clinical significance and potential therapeutic role of GPx3 in tumor recurrence after liver transplantation

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Clinical significance and therapeutic value of glutathione peroxidase 3 (GPx3) in hepatocellular carcinoma

AIMS: We aimed to investigate the clinical significance of GPx3 in hepatocellular carcinoma (HCC) and to characterize its tumor suppressive role. METHODS: HCC patients (113) who underwent hepatectomy were recruited to examine the clinical relevance of GPx3. The tumor suppressive role of GPx3 was studied by administration of recombinant GPx3 (rGPx3) or over-expression of GPx3 in HCC cells in vitro and in vivo. The therapeutic value of GPx3 for HCC was further investigated using human induced pluripotent stem cell derived mesenchymal stem cells (hiPSC-MSCs) as its delivery vehicle. RESULTS: Down-regulation of GPx3 significantly correlated with advanced tumor stage (P = 0.024), venous infiltration (P = 0.043) and poor overall survival (P = 0.007) after hepatectomy. Lower plasma GPx3 in HCC patients was significantly associated with larger tumor size (P = 0.011), more tumor nodules (P = 0.032) and higher recurrence (P = 0.016). Over-expression of GPx3 or administration of rGPx3 significantly inhibited proliferation and invasiveness of HCC cells in vitro and in vivo. Tumor suppressive activity of GPx3 was mediated through Erk-NFκB-SIP1 pathway. GPx3 could be delivered by hiPSC-MSCs into the tumor and exhibited tumor suppressive activity in vivo. CONCLUSIONS: GPx3 is a tumor suppressor gene in HCC and may possess prognostic and therapeutic value for HCC patients.published_or_final_versio