321 research outputs found

    Characterization by mercury porosimetry of nonwoven fiber media with deformation

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    The porosity and pore diameter distribution are important characteristics of nonwoven fiber media. With the advent of electrospinning, the production of mats of nonwoven fibrous materials with fiber diameters in the 0.1-10 mu m range has become more prevalent. The large compliance of these mats makes them susceptible to mechanical deformation under the pressures attained in a typical mercury porosimetry experiment. We report a theoretical analysis of the liquid volume measured during liquid intrusion porosimetry in the presence of deformation of such mats by one of two modes: buckling of the pores or elastic compression of the mat. For electrospun mats of poly(epsilon-caprolactone) with average fiber diameters ranging from 2.49 to 18.0 mu m, we find that buckling is the more relevant mode of deformation, and that it can alter significantly the determination of pore diameter distributions measured by mercury porosimetry.United States. Army Research Office (Institute for Soldier Nanotechnologies, Contract No. DAAD-19-02-D-0002)Massachusetts Institute of Technology (Nicolas G. and Dorothea K. Dumbros Scholarship and Fellowship Fund

    Traverse surveys

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    Thesis (BS)--University of Illinois, 1894Typescrip

    College Student Perceptions on Campus Alcohol Policies and Consumption Patterns

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    Environmental strategies for colleges and universities to reduce alcohol consumption among their students include the development and enforcement of campus alcohol policies. This study examines students\u27 knowledge and attitudes toward campus alcohol policies and how they relate to alcohol consumption and alcohol social norms. A sample of 422 freshman students was surveyed during their first month at a 4-year public college. Findings indicated that the majority of students (89%) were aware of campus policies, yet of those who were aware, less than half (44%) were accepting of these campus rules and regulations. In addition, the majority (79%) of students drank at social events, despite this behavior is in direct violation of campus alcohol policies. However, those who supported campus rules consumed significantly less alcohol at social events than those who opposed or had no opinion of the rules. Also, those who supported the rules perceived that their peers and students, in general, consumed significantly less alcohol at social events than those who were opposed or had no opinion. This outcome supports the premise established by several theories of behavior change including the theory of planned behavior, which states that behavior is influenced less by knowledge than by attitude and intention

    Are clergy serving yoked congregations more vulnerable to burnout? : a study among clergy serving in the Presbyterian church (USA)

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    Pressures generated by increasing secularization and decreasing vocations to ordained ministry are resulting across denominations in a growing number of clergy serving more than one congregation. This study assesses the hypothesis that clergy serving more than one congregation are more susceptible to burnout. Data were provided by a sample of 735 clergy serving in The Presbyterian Church (USA) who completed the Francis Burnout Inventory together with the abbreviated Eysenck Personality Questionnaire Revised. Among these clergy, 82% served one congregation, 13% served two congregations, and 5% served three or more congregations. After controlling for individual differences in age and personality, the data demonstrated that clergy serving yoked congregations experienced no statistically significant differences in susceptibility to burnout, either in terms of levels of emotional exhaustion or in terms of levels of satisfaction in ministry, compared with colleagues serving just one congregation

    Work-related psychological health among clergywomen in Australia

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    Drawing on the classic model of balanced affect, the Francis Burnout Inventory conceptualises good work-related psychological health among clergy in terms of negative affect being balanced by positive affect. This paper sets out to explore the relationship between work-related psychological health and psychological type (as assessed by the Francis Psychological-Type Scales) among a sample of 212 Australian clergywomen who completed the National Church Life Survey Form L in 2006. The data supported the internal consistency reliability of the Francis Burnout Inventory and Francis Psychological-Type Scales and found that work-related psychological health was positively related to extraversion and sensing

    On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

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    The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic

    Calibration and Characterization of the IceCube Photomultiplier Tube

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    Over 5,000 PMTs are being deployed at the South Pole to compose the IceCube neutrino observatory. Many are placed deep in the ice to detect Cherenkov light emitted by the products of high-energy neutrino interactions, and others are frozen into tanks on the surface to detect particles from atmospheric cosmic ray showers. IceCube is using the 10-inch diameter R7081-02 made by Hamamatsu Photonics. This paper describes the laboratory characterization and calibration of these PMTs before deployment. PMTs were illuminated with pulses ranging from single photons to saturation level. Parameterizations are given for the single photoelectron charge spectrum and the saturation behavior. Time resolution, late pulses and afterpulses are characterized. Because the PMTs are relatively large, the cathode sensitivity uniformity was measured. The absolute photon detection efficiency was calibrated using Rayleigh-scattered photons from a nitrogen laser. Measured characteristics are discussed in the context of their relevance to IceCube event reconstruction and simulation efforts.Comment: 40 pages, 12 figure
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