738 research outputs found

    Science in the Middle School Revisited: Contrasting 1965 with 1990

    Get PDF
    Describing science as middle school students experience it continues to be a challenge. The science that students experience in the classroom is that which their teachers have selected and organized for them. This selection/organization process is itself guided by the teacher\u27s knowledge base and the expectations of the schooling context. Presented here is a contrast practiced in the middle school in 1990 with 1965. The findings show that while teachers today may be better prepared in terms of academic courses, they are still not being adequately prepared to work with the emerging adolescent in the middle school

    The Business Case for the Efficiency and Effectiveness of Tele-Intensive Care Units

    Get PDF
    A tele-Intensive Care Unit (tele-ICU) is the use of telemedicine in an Intensive Care Unit (ICU) setting, using technology to provide care to critically ill patients by off-site clinical resources. This literature review examined a large number of studies of the implementation of tele-ICU systems in hospitals. Generally, implementation of a tele-ICU system was associated with cost savings, shorter lengths of stay, and decreased mortality. Implementation of tele-ICUs is initially relatively expensive but result in cost savings and better clinical outcomes. Intensivists working these systems are used more effective providing better clinical outcomes for patients at lower costs for hospitals

    Comparison of DMSP cross-track ion drifts and SuperDARN line-of-sight velocities

    Get PDF
    Cross-track ion drifts measured by the DMSP satellites are compared with line-of-sight SuperDARN HF velocities in approximately the same directions. Good overall agreement is found for a data set comprising of 209 satellite passes over the field of view of nine SuperDARN radars in both the Northern and Southern Hemispheres. The slope of the best linear fit line relating the SuperDARN and DMSP velocities is of the order of 0.7 with a tendency for SuperDARN velocities to be smaller. The agreement implies that the satellite and radar data can be merged into a common set provided that spatial and temporal variations of the velocity as measured by both instruments are smooth.<br><br> <b>Keywords.</b> Ionosphere (Ionospheric irregularities; Plasma convection; Auroral ionosphere

    An Inservice Model to Impact Life Science Classroom Practice: Part One

    Get PDF
    A model inservice program built on a theoretical foundation for changing behavior incorporates both teachers\u27 knowledge, their attitudes as well as what they do. What teachers do in the classroom depends on both what they know and how they feel about what they know, Changing what teachers know and do is accomplished in a three phase sequence, awareness, arousal and action. In the awareness phase, teachers are confronted with their knowledge needs. In the arousal phase, teacher generate interest in using what they know. Action is reflected in what teachers do and is reinforced when they have time to reflect on that action, its effect, its value and acceptance

    An Inservice Model to Impact Life-Science Classroom Practice: Part Two

    Get PDF
    This model for an inservice program describes why teachers change the nature of their students\u27 experiences in science. In the evaluation study with 7th grade Life Science teachers in Southeast, evidence showed that as teachers\u27 knowledge in specific topics in biology was enhanced, their classroom use of this knowledge also changed. As their knowledge of science and alternative teaching practices was expanded, their attitudes toward teaching showed that they were more aware that there was more to learn but were also more confident that they could acquire the new knowledge they needed. In their classroom, their concerns for students showed significant shifts toward involving students more in their learning rather than being most concerned about managing or controlling them. This was especially true if there was an institutional willingness for them to use different teaching strategies. Thus based on this evaluation study, teachers are more likely to change if the changes are consistent with the external demands of their schooling context; and their internal belief systems

    Magnetospheric Response Times Following Southward IMF Turnings

    Get PDF
    We analyze the response times of various regions of the magnetosphere-ionosphere system to sudden southward turnings of the IMF. Our data set consists of 26 events during which the IMP BZ component was observed by WIND to change from a stea northward field to a southward field, which subsequently led to a substorm. The magnetospheric response to such IMF southward turnings is examined using data from the POLAR EFI experiment, the GOES 9 magnetometer, and ground magnetometers. The POLAR/EFI was used to investigate changes in the polar cap electric field which occurred in response to the changing interplanetary electric field, and these results are compared with response timings derived from high-latitude ground magnetometers. POLAR/EFI data show responses in the polar cap about 15 minutes after the arrival of the IMF change at the magnetopause. Auroral zone magnetograms and geosynchronous spacecraft measurements are utilized to evaluate the response timing within the closed field line region. In one event examined in detail, the start of a substorm growth phase was observed by GOES 9 in the midnight sector of geosynchronous orbit about two minutes before POLAR observed a response in the polar cap. Using superposed epoch analysis, we calculate typical response times in the polar cap, in the nightside plasma sheet, and in the ionosphere in order to discuss the various suggested mechanisms for information propagation from the subsolar magnetopause into the magnetosphere. We find that for the set of ten events for which the GOES 9 and the CANOPUS array are in the midnight sector, the field at geosynchronous as measured by GOES responds at or before the time of response in the polar cap as measured by POLAR, suggesting different methods of information propagation

    Effects of rapid prey evolution on predator-prey cycles

    Full text link
    We study the qualitative properties of population cycles in a predator-prey system where genetic variability allows contemporary rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk can have major quantitative and qualitative effects on predator-prey cycles, including: (i) large increases in cycle period, (ii) changes in phase relations (so that predator and prey are cycling exactly out of phase, rather than the classical quarter-period phase lag), and (iii) "cryptic" cycles in which total prey density remains nearly constant while predator density and prey traits cycle. Here we focus on a chemostat model motivated by our experimental system [Fussmann et al. 2000,Yoshida et al. 2003] with algae (prey) and rotifers (predators), in which the prey exhibit rapid evolution in their level of defense against predation. We show that the effects of rapid prey evolution are robust and general, and furthermore that they occur in a specific but biologically relevant region of parameter space: when traits that greatly reduce predation risk are relatively cheap (in terms of reductions in other fitness components), when there is coexistence between the two prey types and the predator, and when the interaction between predators and undefended prey alone would produce cycles. Because defense has been shown to be inexpensive, even cost-free, in a number of systems [Andersson and Levin 1999, Gagneux et al. 2006,Yoshida et al. 2004], our discoveries may well be reproduced in other model systems, and in nature. Finally, some of our key results are extended to a general model in which functional forms for the predation rate and prey birth rate are not specified.Comment: 35 pages, 8 figure

    Rapid contemporary evolution and clonal food web dynamics

    Full text link
    Character evolution that affects ecological community interactions often occurs contemporaneously with temporal changes in population size, potentially altering the very nature of those dynamics. Such eco-evolutionary processes may be most readily explored in systems with short generations and simple genetics. Asexual and cyclically parthenogenetic organisms such as microalgae, cladocerans, and rotifers, which frequently dominate freshwater plankton communities, meet these requirements. Multiple clonal lines can coexist within each species over extended periods, until either fixation occurs or a sexual phase reshuffles the genetic material. When clones differ in traits affecting interspecific interactions, within-species clonal dynamics can have major effects on the population dynamics. We first consider a simple predator-prey system with two prey genotypes, parameterized with data on a well-studied experimental system, and explore how the extent of differences in defense against predation within the prey population determine dynamic stability versus instability of the system. We then explore how increased potential for evolution affects the community dynamics in a more general community model with multiple predator and multiple prey genotypes. These examples illustrate how microevolutionary "details" that enhance or limit the potential for heritable phenotypic change can have significant effects on contemporaneous community-level dynamics and the persistence and coexistence of species.Comment: 30 pages, 6 Figure
    • …
    corecore