969 research outputs found

    A preferred vision for administering high schools : a reflective essay

    Get PDF
    If a person wants to succeed on becoming a principal, a leader, that person has to understand what people want and need. A principal needs to learn how to listen and talk with people. He also needs to understand different cultures, because not everyone is the same. There is an important relationship between the law and protection of the students as well as the staff. A principal needs to have a sense of humor. Laugh with the students and the staff. Others will understand him as a human. He needs to be strong. People like to mock policies or complain when something doesn\u27t benefit their needs. A principal needs to keep pushing forward with ideas and creativity. The school is a setting for bringing about knowledge and success. In order to succeed, he must find the best resources available to achieve his school\u27s needs, even if they are limited. The principal doesn\u27t become a leader because of his title; he becomes a leader because he can convince the community, staff, and students to believe in him

    Cavity optoelectromechanical regenerative amplification

    Get PDF
    Cavity optoelectromechanical regenerative amplification is demonstrated. An optical cavity enhances mechanical transduction, allowing sensitive measurement even for heavy oscillators. A 27.3 MHz mechanical mode of a microtoroid was linewidth narrowed to 6.6\pm1.4 mHz, 30 times smaller than previously achieved with radiation pressure driving in such a system. These results may have applications in areas such as ultrasensitive optomechanical mass spectroscopy

    Lessons learned from a peri-urban needle exchange

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Injection drug users continue to be at high risk of HIV and HCV. Research has shown that needle exchange programs (NEP) decrease injection frequency, reduce syringe reuse, and reduce needle sharing, though some results have been mixed.</p> <p>Methods</p> <p>This evaluation of a small, peri-urban, legal NEP near Ypsilanti, Michigan describes the operation of the NEP and its clients. It uses interviews conducted with NEP participants between 2003 and 2006, describing the population served by the program, and draws on limited comparisons between matched baseline and follow-up measures as well as aggregate baseline and follow-up comparisons.</p> <p>Results</p> <p>The HIV/AIDS Resource Center (HARC) Harm Reduction NEP serves a diverse population from a wide geographical area. NEP participants at follow-up reused their syringes significantly fewer times before getting new ones, were significantly less likely to report giving another IDU a previously used syringe, and were more likely to clean their skin with alcohol either before or after injecting than the baseline comparison group.</p> <p>Conclusions</p> <p>The limited data presented here suggest that a NEP can be an effective method of harm reduction even in low-volume, non-urban settings and are an important venue for intervention in peri-urban areas.</p

    Fundamental constraints on particle tracking with optical tweezers

    Full text link
    A general quantum limit to the sensitivity of particle position measurements is derived following the simple principle of the Heisenberg microscope. The value of this limit is calculated for particles in the Rayleigh and Mie scattering regimes, and with parameters which are relevant to optical tweezers experiments. The minimum power required to observe the zero-point motion of a levitating bead is also calculated, with the optimal particle diameter always smaller than the wavelength. We show that recent optical tweezers experiments are within two orders of magnitude of quantum limited sensitivity, suggesting that quantum optical resources may soon play an important role in high sensitivity tracking applications

    Expression of ECM proteins fibulin-1 and -2 in acute and chronic liver disease and in cultured rat liver cells

    Get PDF
    Fibulin-2 has previously been considered as a marker to distinguish rat liver myofibroblasts from hepatic stellate cells. The function of other fibulins in acute or chronic liver damage has not yet been investigated. The aim of this study has been to evaluate the expression of fibulin-1 and -2 in models of rat liver injury and in human liver cirrhosis. Their cellular sources have also been investigated. In normal rat liver, fibulin-1 and -2 were both mainly present in the portal field. Fibulin-1-coding transcripts were detected in total RNA of normal rat liver, whereas fibulin-2 mRNA was only detected by sensitive, real-time quantitative polymerase chain reaction. In acute liver injury, the expression of fibulin-1 was significantly increased (17.23-fold after 48 h), whereas that of fibulin-2 was not modified. The expression of both fibulin-1 and -2 was increased in experimental rat liver cirrhosis (19.16- and 26.47-fold, respectively). At the cellular level, fibulin-1 was detectable in hepatocytes, “activated” hepatic stellate cells, and liver myofibroblasts (2.71-, 122.65-, and 469.48-fold over the expression in normal rat liver), whereas fibulin-2 was restricted to liver myofibroblasts and was regulated by transforming growth factor beta-1 (TGF-β1) in 2-day-old hepatocyte cultures and in liver myofibroblasts. Thus, fibulin-1 and -2 respond differentially to single and repeated damaging noxae, and their expression is differently present in liver cells. Expression of the fibulin-2 gene is regulated by TGF-β1 in liver myofibroblasts

    Gravity-Assist Trajectories to the Ice Giants: An Automated Method to Catalog Mass- Or Time-Optimal Solutions

    Get PDF
    This work presents an automated method of calculating mass (or time) optimal gravity-assist trajectories without a priori knowledge of the flyby-body combination. Since gravity assists are particularly crucial for reaching the outer Solar System, we use the Ice Giants, Uranus and Neptune, as example destinations for this work. Catalogs are also provided that list the most attractive trajectories found over launch dates ranging from 2024 to 2038. The tool developed to implement this method, called the Python EMTG Automated Trade Study Application (PEATSA), iteratively runs the Evolutionary Mission Trajectory Generator (EMTG), a NASA Goddard Space Flight Center in-house trajectory optimization tool. EMTG finds gravity-assist trajectories with impulsive maneuvers using a multiple-shooting structure along with stochastic methods (such as monotonic basin hopping) and may be run with or without an initial guess provided. PEATSA runs instances of EMTG in parallel over a grid of launch dates. After each set of runs completes, the best results within a neighborhood of launch dates are used to seed all other cases in that neighborhood-allowing the solutions across the range of launch dates to improve over each iteration. The results here are compared against trajectories found using a grid-search technique, and PEATSA is found to outperform the grid-search results for most launch years considered

    Subsurface microbial methanotrophic mats in the Black Sea

    Get PDF
    A nodule-shaped microbial mat was found subsurface in sediments of a gas seep in the anoxic Black Sea. This mat was dominated by ANME-1 archaea and consumed methane and sulfate simultaneously. We propose that such subsurface mats represent the initial stage of previously investigated microbial reefs

    Cavity Optomechanical Magnetometer

    Get PDF
    A cavity optomechanical magnetometer is demonstrated where the magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly compliant optical microresonator. The resulting motion is read out optically with ultra-high sensitivity. Detecting the magnetostrictive deformation of Terfenol-D with a toroidal whispering gallery mode (TWGM) resonator a peak sensitivity of 400 nT/Hz^.5 was achieved with theoretical modelling predicting that sensitivities of up to 500 fT/Hz^.5 may be possible. This chip-based magnetometer combines high-sensitivity and large dynamic range with small size and room temperature operation

    Analyzing the Creative Problem-Solving Process: Inventing a Product from a Given Recyclable Item

    Get PDF
    Detailed documentations of creative invention are scarce in the professional literature, but could be useful to those engaging in or studying the problem solving process. This investigation describes the creative process of graduate students (7 female, 4 male) in a problem-solving theory and practice course grappling with the task of creating products from four identical recyclable items that were circular, star-impressed bottoms of plastic juice bottles. Several popular models of the problem-solving process are compared to the participants’ steps in this invention problem. Participants first provided emotional reactions to the given ill-defined problem of making a product from the specified items. They used several techniques to generate ideas and to restrict or define the problem, choosing an optimal product that fits their require-ments. An analysis of participants’ reflections concerning their creative process showed that although participants first found the problem challenging and could not conceptualize effective products, the idea-generating activities assisted them in making a wide variety of useful products. Participants’ knowledge and skill areas were highlighted by their choices of products. After completing and presenting a first product, participants engaged in additional activities to generate ideas for a second product. The second product was either an improvement of the first product, a new but related product, or a product inspired by the work of others in the class. Products of this loosely defined problem included: maracas, dish, spin top, candy suckers, closet organizers, party decorations, yoyo, ladybug, wall décor, flowers, catch game, party hat, candle holders, moth life cycle, catapult game, toy clock, goblets, castanets, accessory organizer, and spice shaker
    • …
    corecore