Subthreshold characteristics of pentacene field-effect transistors influenced by grain boundaries.

Grain boundaries in polycrystalline pentacene films significantly affect the electrical characteristics of pentacene field-effect transistors (FETs). Upon reversal of the gate voltage sweep direction, pentacene FETs exhibited hysteretic behaviours in the subthreshold region, which was more pronounced for the FET having smaller pentacene grains. No shift in the flat-band voltage of the metal-insulator-semiconductor capacitor elucidates that the observed hysteresis was mainly caused by the influence of localized trap states existing at pentacene grain boundaries. From the results of continuous on/off switching operation of the pentacene FETs, hole depletion during the off period is found to be limited by pentacene grain boundaries. It is suggested that the polycrystalline nature of a pentacene film plays an important role on the dynamic characteristics of pentacene FETs

Cosmological Solutions of Higher-Curvature String Effective Theories with Dilatons

We study the effect of higher-curvature terms in the string low-energy effective actions on the cosmological solutions of the theory, up to corrections quartic in the curvatures, for the bosonic and heterotic strings as well as the type II superstring. We find that cosmological solutions exist for all string types but they always disappear when the dilaton field is included, a conclusion that can be avoided if string-loop effects are taken into account.Comment: 7 pages, plain Tex with panda.tex macro (included), no figure

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

AbstractObjective: To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes.Design: Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1β. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1β-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting.Results: The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100μM of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50μM. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10μM. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1β, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50μM, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level.Conclusions: Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100μM of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss

Mobile Self-Efficacy in a Canadian Nursing Education Program

The purpose of this study was to assess the self-efficacy of nursing faculty and students related to their potential use of mobile technology and to ask what are the implications for their teaching and learning in practice education contexts. We used a cross-sectional survey design involving students and faculty in two nursing education programs in a Western Canadian college. 121 faculty members and students completed the survey in January, 2011. Results showed a high level of ownership and use of mobile devices among our respondents. Their median mobile self-efficacy score was 75 on a scale of 100, indicating that they are highly confident in their use of mobile technologies and prepared to engage in mobile learning

Mobile Self Efficacy in Canadian Nursing Education Programs

The purpose of this study was to assess the self-efficacy of nursing faculty and students related to their potential use of mobile technology and to ask what are the implications for their teaching and learning in practice education contexts. We used a cross-sectional survey design involving students and faculty in three separate nursing education programs in Western Canada. Fifty-six faculty members and students completed the survey in March, 2010. Results showed a high level of ownership and use of mobile devices among our respondents. Their overall average mobile self-efficacy score was 72.11 on a scale of 100, indicating that they are highly confident in their use of mobile technologies and prepared to engage in mobile learning

Electrical and ultraviolet characterization of 4H-SiC Schottky photodiodes

Fabrication and electrical and optical characterization of 4H-SiC Schottky UV photodetectors with nickel silicide interdigitated contacts is reported. Dark capacitance and current measurements as a function of applied voltage over the temperature range 20 °C – 120 °C are presented. The results show consistent performance among devices. Their leakage current density, at the highest investigated temperature (120 °C), is in the range of nA/cm2 at high internal electric field. Properties such as barrier height and ideality factor are also computed as a function of temperature. The responsivities of the diodes as functions of applied voltage were measured using a UV spectrophotometer in the wavelength range 200 nm - 380 nm and compared with theoretically calculated values. The devices had a mean peak responsivity of 0.093 A/W at 270 nm and −15 V reverse bias

Hepatitis C Virus NS5B Protein Is a Membrane-Associated Phosphoprotein with a Predominantly Perinuclear Localization

AbstractHepatitis C virus NS5B protein is an RNA-dependent RNA polymerase. To investigate the properties and function of this protein, we have expressed the NS5B protein in insect and mammalian cells. NS5B was found to be present as fine speckles in the cytoplasm, particularly concentrated in the perinuclear region, suggesting its association with the nuclear membrane, the endoplasmic reticulum, or the Golgi complex. This conclusion was supported by the biochemical demonstration that NS5B was associated with the membranes in the cells. Furthermore, it was shown that NS5B protein is a phosphoprotein. These properties may be related to its function as an RNA polymerase

Mobile Learning in Nursing Practice Education: Applying Koole's FRAME Model

We report here on an exploratory formative evaluation of a project to integrate mobile learning into a Western Canadian college nursing program. Third-year students used Hewlett Packard iPAQ mobile devices for five weeks in a practice education course in April—May, 2007. Koole's (2009) Framework for the Rational Analysis of Mobile Education (FRAME) model provided our definition of mobile learning and was used to organize our presentation of the results of the study. Participants reported positively on the usability of the mobile devices, finding them easy to learn, readily portable, and the screen size sufficient for mobile specific programs. However, they had difficulty with the wireless connectivity and, despite an initial orientation, did not have time to fully learn the devices in the context of a busy course. As a result, it is not clear if students can effectively use the social technology provided by such devices or if mobile learning can support interaction between instructors and learners in this context. The use of mobile devices in nursing practice education is feasible, but further investigation is needed on the use of m-learning for communication and interactive purposes

Using Self-Efficacy to Assess the Readiness of Nursing Educators and Students for Mobile Learning

The purpose of this study was to assess the self-efficacy of nursing faculty and students related to their potential use of mobile technology and to ask what implications this technology has for their teaching and learning in practice education contexts. We used a cross-sectional survey design involving students and faculty in two nursing education programs in a western Canadian college. In January, 2011, 121 faculty members and students completed the survey. Results showed a high level of ownership and use of mobile devices among our respondents. The median mobile self-efficacy score was 75 on a scale of 100, indicating that both faculty and students were highly confident in their use of mobile technologies and prepared to engage in mobile learning

Using Mobile Learning to Enhance the Quality of Nursing Practice Education

In this chapter, we first review the research literature pertaining to the use of mobile devices in nursing education and assess the potential of mobile learning (m-learning) for nursing practice education experiences in rural higher education settings. While there are a number of definitions of m-learning, we adopted Koole’s (2005) FRAME model, which describes it as a process resulting from the convergence of mobile technologies, human learning capacities, and social interaction, and use it as a framework to assess this literature. Second, we report on the results of one-on-one trials conducted during the first stage of a two stage, exploratory evaluation study of a project to integrate mobile learning into the Bachelor of Science Nursing curriculum in a Western Canadian college program. Fourth year Nursing students and instructors used Hewlett Packard iPAQ PDAs for a two week period around campus and the local community. The iPAQs provided both WiFi and GPRS wireless capability and were loaded with selected software, including MS Office Mobile, nursing decision-making and drug reference programs. Our participants reported on a variety of benefits and barriers to the use of these devices in nursing practice education