4,483 research outputs found

    Multispectral mapping of the lunar surface using groundbased telescopes

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    Images of the lunar surface were obtained at several wavelengths using a silicon vidicon imaging system and groundbased telescopes. These images were recorded and processed in digital form so that quantitative information is preserved. The photometric precision of the images is shown to be better than 1 percent. Ratio images calculated by dividing images obtained at two wavelengths (0.40/0.56 micrometer) and 0.95/0.56 micrometer are presented for about 50 percent of the lunar frontside. Spatial resolution is about 2 km at the sub-earth point. A complex of distinct units is evident in the images. Earlier work with the reflectance spectrum of lunar materials indicates that for the most part these units are compositionally distinct. Digital images of this precision are extremely useful to lunar geologists in disentangling the history of the lunar surface

    Nonverbal Evidence of Displaced Intergroup Affect

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    This study examined the effects of racial insult on the propensity to either categorize or individuate outgroup members. Reaction times and self-reports measures were employed to gauge reactions to an insulting video. White and African American participants heard an insult, and then completed the Go/No-Go Association Task (GNAT), as well as the Internal Motivation to Control Prejudice Scale (IMS) and the External Motivation to Control Prejudice Scale (IMS), the Motivation to Control Prejudice Scale (MCPRS) the Social Distance Scale (SDS), and made ratings on a feeling thermometer about the people in the insult video. African Americans showed more negative responses to outgroup members than Whites on the explicit measure, but Whites showed more negative responses to outgroup members than African Americans on the implicit measure

    Evidence for a dynamic phase transition in [Co/Pt]_3 magnetic multilayers

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    A dynamic phase transition (DPT) with respect to the period P of an applied alternating magnetic field has been observed previously in numerical simulations of magnetic systems. However, experimental evidence for this DPT has thus far been limited to qualitative observations of hysteresis loop collapse in studies of hysteresis loop area scaling. Here, we present significantly stronger evidence for the experimental observation of this DPT, in a [Co(4 A)/Pt(7 A)]_3-multilayer system with strong perpendicular anisotropy. We applied an out-of-plane, time-varying (sawtooth) field to the [Co/Pt]_3 multilayer, in the presence of a small additional constant field, H_b. We then measured the resulting out-of-plane magnetization time series to produce nonequilibrium phase diagrams (NEPDs) of the cycle-averaged magnetization, Q, and its variance, Var(Q), as functions of P and H_b. The experimental NEPDs are found to strongly resemble those calculated from simulations of a kinetic Ising model under analagous conditions. The similarity of the experimental and simulated NEPDs, in particular the presence of a localized peak in the variance Var(Q) in the experimental results, constitutes strong evidence for the presence of this DPT in our magnetic multilayer samples. Technical challenges related to the hysteretic nature and response time of the electromagnet used to generate the time-varying applied field precluded us from extracting meaningful critical scaling exponents from the current data. However, based on our results, we propose refinements to the experimental procedure which could potentially enable the determination of critical exponents in the future.Comment: substantial revision; 26 pages, 9 figures; to appear in Phys. Rev.

    Approach to Teaching Research Methodology for Information Technology

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    The paper reports on an approach to teaching a course in information technology research methodology in a doctoral program, the Doctor of Management in Information Technology (DMIT), in which research, with focus on finding innovative solutions to problems found in practice, comprises a significant part of the degree. The approach makes a contribution by preparing doctoral students, who are experienced professionals studying part-time, for dissertation research. The rationale of the DMIT and the educational objectives of the course are presented. A research process model applicable to applied research in information technology (IT) is proposed and discussed. This model accommodates scientific methods of research, including empirical, quantitative, qualitative, case study and mixed methods. The course design and pedagogical approach are described in terms of thematic areas of scholarship and practice, and intended outcomes. The paper summarizes the topics of the syllabus, including proposal formulation; research design; methods of investigation; methods of demonstrating concept; approaches to research validation; and documenting research results in the form of technical papers and the dissertation. The purpose of the paper is to share the approach followed in teaching the course, the course design, a summary of lessons learned after several offerings of the course, and ideas for further improvement

    A feasibility test of an online intervention to prevention dating violence in emerging adults

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    Dating violence in emerging adults is a significant problem and few prevention programs based on the developmental needs of this age group have been developed. Our research team developed an online dating violence prevention program called WISER (Writing to Improve Self-in-Relationships) for emerging adults. The program is based on narrative therapy principles and uses structured writing techniques. A single group pre-post feasibility test of WISER was conducted with 14 college women. WISER was demonstrated to be feasible and acceptable and to show promise as an effective program to decrease dating violence in this population

    A Window of Opportunity: Subdominant Predators Can Use Suboptimal Prey

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    Introduced species have been linked to declines of native species through mechanisms including intraguild predation and exploitative competition. However, coexistence among species may be promoted by niche partitioning if native species can use resources that the invasive species cannot. Previous research has shown that some strains of the aphid Aphis craccivora are toxic to a competitively dominant invasive lady beetle, Harmonia axyridis. Our objective was to investigate whether these aphids might be an exploitable resource for other, subdominant, lady beetle species. We compared larval development rate, survival, and adult weight of five lady beetle species in no-choice experiments with two different strains of A. craccivora, one of which is toxic to H. axyridis and one that is nontoxic. Two lady beetle species, Cycloneda munda and Coleomegilla maculata, were able to complete larval development when feeding on the aphid strain that is toxic to H. axyridis, experiencing only slight developmental delays relative to beetles feeding on the other aphid strain. One species, Coccinella septempunctata, also was able to complete larval development, but experienced a slight reduction in adult weight. The other two lady beetle species, Hippodamia convergens and Anatis labiculata, demonstrated generally low survivorship when consuming A. craccivora, regardless of aphid strain. All five species showed increased survival and/or development relative to H. axyridis on the “toxic” aphid strain. Our results suggest that this toxic trait may act as a narrow-spectrum defense for the aphids, providing protection against only some lady beetle enemies. For other less-susceptible lady beetles, these aphids have the potential to provide competitive release from the otherwise dominant H. axyridis

    The Formation and Coarsening of the Concertina Pattern

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    The concertina is a magnetization pattern in elongated thin-film elements of a soft material. It is a ubiquitous domain pattern that occurs in the process of magnetization reversal in direction of the long axis of the small element. Van den Berg argued that this pattern grows out of the flux closure domains as the external field is reduced. Based on experimental observations and theory, we argue that in sufficiently elongated thin-film elements, the concertina pattern rather bifurcates from an oscillatory buckling mode. Using a reduced model derived by asymptotic analysis and investigated by numerical simulation, we quantitatively predict the average period of the concertina pattern and qualitatively predict its hysteresis. In particular, we argue that the experimentally observed coarsening of the concertina pattern is due to secondary bifurcations related to an Eckhaus instability. We also link the concertina pattern to the magnetization ripple and discuss the effect of a weak (crystalline or induced) anisotropy
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