666 research outputs found

    Ion-channel-like behavior in lipid bilayer membranes at the melting transition

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    It is well known that at the gel-liquid phase transition temperature a lipid bilayer membrane exhibits an increased ion permeability. We analyze the quantized currents in which the increased permeability presents itself. The open time histogram shows a "-3/2" power law which implies an open-closed transition rate that decreases like k(t)t1k(t) \propto t^{-1} as time evolves. We propose a "pore freezing" model to explain the observations. We discuss how this model also leads to the 1/fα1/f^{\alpha} noise that is commonly observed in currents across biological and artificial membranes.Comment: 5 pages, 4 figure

    Cultural/Interpersonal Values and Smoking in an Ethnically Diverse Sample of Southern California Adolescents

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    In ethnically diverse school contexts, values from multiple cultures might influence adolescents\u27 attitudes and behaviors. This study developed scales to assess cultural values among Southern California 6- grade adolescents (N=2281) and evaluated the associations between values and smoking. The scales assessed values salient in many Hispanic and Asian cultures: Respect for Adults (e.g., filial piety, respeto). Interpersonal Harmony (e.g., saving face, simpatia), and Differentiated Gender Roles (e.g., machismo). In cross-sectional and one-year longitudinal models. Respect for Adults and Interpersonal Harmony were associated with a lower risk of lifetime smoking. The associations were significant even after controlling for demographic characteristics, friends\u27 smoking, and parents\u27 smoking, indicating that values influence adolescents\u27 behavior over and above the effects of modeling and peer influence. Increased understanding of adolescents\u27 values could inform the creation of smoking prevention programs for ethnically diverse adolescents

    Coaxial Compound Helicopter for Confined Urban Operations

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    A rotorcraft was designed for military operations in a confined urban environment. The specifications included major increases in useful load, range, and speed relative current aircraft capabilities, with a size constraint based on the dimensions of urban streets and intersections. Analysis showed that this combination of requirements is best satisfied by a coaxial main-rotor configuration, with lift compounding to off-load the rotors at high speed, and ducted fans under the rotor disk for propulsion. The baseline design is described, and the aircraft performance is summarized for utility, attack, MEDEVAC, and cargo delivery missions. The impact on size and performance is examined for a number of excursions, including lift-offset main rotors. Technology development required to achieve this advance in capability is recommended

    Eschatological anarchism: eschatology and politics in contemporary Greek theology

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    This is the author accepted manuscript. The final version is available from Bloomsbury via the link in this recor

    Godmanhood vs Mangodhood: An eastern orthodox response to transhumanism

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    This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this record.This article distances the classic Patristic teaching of Eastern Orthodoxy on theosis from the pseudo-religious ideology of transhumanism. By appealing to the Silver Age of Russian theologians a century ago, today’s transhumanist vision is dubbed Mangodhood, an idolatrous construction of a technological Tower of Babel. In contrast, the classical Orthodox teaching of deification or theosis relies on the spiritual grace of the true God, rendering the true goal of religion to be Godmanhood

    Multiple Peer Group Self-identification and Adolescent Tobacco Use

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    Associations between peer group self-identification and smoking were examined among 2,698 ethnically diverse middle school students in Los Angeles who self-identified with groups such as Rockers, Skaters, and Gamers. The sample was 47.1% male, 54.7% Latino, 25.4% Asian, 10.8% White, 9.1% Other ethnicity, and 59.3% children of immigrant parents. Multiple group self identification was common: 84% identified with two or more groups and 65% identified with three or more groups. Logistic regression analyses indicated that as students endorsed more high risk groups, the greater their risk of tobacco use. A classification tree analysis identified risk groups based on interactions among ethnicity, gender, and group self-identification. Psychographic targeting based on group self-identification could be useful to design more relevant smoking prevention messages for adolescents who identify with high-risk peer groups

    Internet Accessibility and Usage among Urban Adolescents in Southern California: Implications for Web-Based Health Research

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    The World Wide Web (WWW) poses a distinct capability to offer interventions tailored to the individual’s characteristics. To fine tune the tailoring process, studies are needed to explore how Internet accessibility and usage are related to demographic, psychosocial, behavioral, and other health related characteristics. This study was based on a cross-sectional survey conducted on 2373 7th grade students of various ethnic groups in Southern California. Measures of Internet use included Internet use at school or at home, Email use, chat-room use, and Internet favoring. Logistic regressions were conducted to assess the associations between Internet uses with selected demographic, psychosocial, behavioral variables and self-reported health statuses. The proportion of students who could access the Internet at school or home was 90% and 40%, separately. Nearly all (99%) of the respondents could access the Internet either at school or at home. Higher SES and Asian ethnicity were associated with higher internet use. Among those who could access the Internet and after adjusting for the selected demographic and psychosocial variables, depression was positively related with chat-room use and using the Internet longer than 1 hour per day at home, and hostility was positively related with Internet favoring (All ORs = 1.2 for +1 STD, p \u3c 0.05). Less parental monitoring and more unsupervised time were positively related to email use, chat-room use, and at home Internet use (ORs for +1 STD ranged from 1.2 to 2.0, all p \u3c 0.05), but not related to at school Internet use. Substance use was positively related to email use, chat-room use, and at home Internet use (OR for “used” vs. “not used” ranged from 1.2 to 4.0, p \u3c 0.05). Self-reported health problems were associated with higher levels of Internet use at home but lower levels of Internet use at school. More physical activity was related to more email use (OR = 1.3 for +1 STD), chat room use (OR = 1.2 for +1 STD), and at school ever Internet use (OR = 1.2 for +1 STD, all p \u3c 0.05). Body mass index was not related to any of the Internet use-related measures. In this ethnically diverse sample of Southern California 7th grade students, 99% could access the Internet at school and/or at home. This suggests that the Internet is already a potential venue for large scale health communication studies. Adolescents with more psychosocial risk factors or detrimental health behaviors were more likely to use the Internet. Therefore, if used properly, Internet interventions could effectively address the high risk populations. Additional research is needed to gain a more complete understanding of the positive and negative consequences of Internet use among adolescents

    Integrating Flight Dynamics & Control Analysis and Simulation in Rotorcraft Conceptual Design

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    The development of a toolset, SIMPLI-FLYD ('SIMPLIfied FLight dynamics for conceptual Design') is described. SIMPLI-FLYD is a collection of tools that perform flight dynamics and control modeling and analysis of rotorcraft conceptual designs including a capability to evaluate the designs in an X-Plane-based real-time simulation. The establishment of this framework is now facilitating the exploration of this new capability, in terms of modeling fidelity and data requirements, and the investigation of which stability and control and handling qualities requirements are appropriate for conceptual design. Illustrative design variation studies for single main rotor and tiltrotor vehicle configurations show sensitivity of the stability and control characteristics and an approach to highlight potential weight savings by identifying over-design

    Ecumenism as civilisational dialogue: Eastern Orthodox anti-ecumenism and Eastern Orthodox ecumenism. A creative or sterile antinomy?

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    This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.It is argued that those who uphold Ecumenism and Anti-Ecumenism in Eastern Orthodoxy share much more in common than is normally thought to be the case. Both groups see the Orthodox Church as the Una Sancta of the Creed and that Orthodoxy must always witness to itself as the fullness of the Christian faith. They also both see ecumenical encounter (whether in dialogue or in condemnation of the Other) as being a species of civilisational dialogue between two very different realities of Christian East and West. Ultimately, it is contended, both parties have much to learn from one another so that their opposition is not a sterile but a creative antinomy
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