20,491 research outputs found
Integrating Information Literacy into the Virtual University: A Course Model
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Quantitative Analysis of Electrotonic Structure and Membrane Properties of NMDA-Activated Lamprey Spinal Neurons
Parameter optimization methods were used to quantitatively analyze frequency-domain-voltage-clamp data of NMDA-activated lamprey spinal neurons simultaneously over a wide range of membrane potentials. A neuronal cable model was used to explicitly take into account receptors located on the dendritic trees. The driving point membrane admittance was measured from the cell soma in response to a Fourier synthesized point voltage clamp stimulus. The data were fitted to an equivalent cable model consisting of a single lumped soma compartment coupled resistively to a series of equal dendritic compartments. The model contains voltage-dependent NMDA sensitive (INMDA), slow potassium (IK), and leakage (IL) currents. Both the passive cable properties and the voltage dependence of ion channel kinetics were estimated, including the electrotonic structure of the cell, the steady-state gating characteristics, and the time constants for particular voltage- and time-dependent ionic conductances. An alternate kinetic formulation was developed that consisted of steady-state values for the gating parameters and their time constants at half-activation values as well as slopes of these parameters at half-activation. This procedure allowed independent restrictions on the magnitude and slope of both the steady-state gating variable and its associated time constant. Quantitative estimates of the voltage-dependent membrane ion conductances and their kinetic parameters were used to solve the nonlinear equations describing dynamic responses. The model accurately predicts current clamp responses and is consistent with experimentally measured TTX-resistant NMDA-induced patterned activity. In summary, an analysis method is developed that provides a pragmatic approach to quantitatively describe a nonlinear neuronal system
Value stability and change during self-chosen life transitions: Self-selection versus socialization effects
Copyright @ 2013 APA. This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.Three longitudinal studies examine a fundamental question regarding adjustment of personal values to self-chosen life transitions: Do values fit the new life setting already at its onset, implying value-based self-selection? Or do values change to better fit the appropriate and desirable values in the setting, implying value socialization? As people are likely to choose a life transition partly based on their values, their values may fit the new life situation already at its onset, leaving little need for value socialization. However, we propose that this may vary as a function of the extent of change the life transition entails, with greater change requiring more value socialization. To enable generalization, we used 3 longitudinal studies spanning 3 different life transitions and different extents of life changes: vocational training (of new police recruits), education (psychology vs. business students), and migration (from Poland to Britain). Although each life transition involved different key values and different populations, across all 3 studies we found value fit to the life situation already early in the transition. Value socialization became more evident the more aspects of life changed as part of the transition, that is, in the migration transition. The discussion focuses on the implications of these findings for research on values and personality change, as well as limitations and future directions for research
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Appreciative Inquiry: A Path to Change in Education
Appreciative Inquiry (AI) introduces a new approach to educational change. Most state and federal initiatives for educational change grow out of a deficit model determined to fix problems. The emphasis of AI is upon what is right with the organization and forms the basis for new initiatives and further change. This model proposes a cycle of inquiry used by leaders who distribute leadership across their constituents. Organizational learning is a process of individual and collective inquiry that modifies or constructs organizational theories-in-use and changes practice.
The study explored the relationship of AI, distributed leadership, and organizational learning qualities that exist within the participating districts in combination with participants’ preparedness for CCSS implementation. To explore the relationships, a survey was created based on four already existing instruments. A model was proposed and path analysis was conducted. Inventories of appreciative capacities and principles, distributed leadership, and organizational learning capabilities in an educational system provided insight into the applicability of using AI as a process for implementation of the CCSS and future educational reforms. Throughout the analysis significant correlations existed and the model held. Utilizing appreciative inquiry, distributed leadership, and organizational leadership singularly or in combination within districts would strengthen CCSS implementation
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Getting creative in everyday life: Investigating arts and crafts hobbyists' information behavior
While there has been increasing interest in how creative professionals find information to drive creative outputs, previous information behavior research has largely ignored how arts and crafts hobbyists look for information sources in their everyday lives. To fill this literature gap, we conducted interviews and observations with arts and crafts hobbyists to find out how they conceive potential DIY projects. The findings highlight three themes: the dearth of human sources, the prevalence of domain-specific information, and the use of self-curated information. In addition to empirical results, this work also broadens the understanding of information behavior in an arts and crafts context by studying populations beyond professional artists
Spitzer IRS Spectra of Luminous 8 micron Sources in the Large Magellanic Cloud: Testing color-based classifications
We present archival Spitzer IRS spectra of 19 luminous 8 micron selected
sources in the Large Magellanic Cloud (LMC). The object classes derived from
these spectra and from an additional 24 spectra in the literature are compared
with classifications based on 2MASS/MSX (J, H, K, and 8 micron) colors in order
to test the "JHK8" classification scheme (Kastner et al. 2008). The IRS spectra
confirm the classifications of 22 of the 31 sources that can be classified
under the JHK8 system. The spectroscopic classification of 12 objects that were
unclassifiable in the JHK8 scheme allow us to characterize regions of the
color-color diagrams that previously lacked spectroscopic verification,
enabling refinements to the JHK8 classification system. The results of these
new classifications are consistent with previous results concerning the
identification of the most infrared-luminous objects in the LMC. In particular,
while the IRS spectra reveal several new examples of asymptotic giant branch
(AGB) stars with O-rich envelopes, such objects are still far outnumbered by
carbon stars (C-rich AGB stars). We show that Spitzer IRAC/MIPS color-color
diagrams provide improved discrimination between red supergiants and
oxygen-rich and carbon-rich asymptotic giant branch stars relative to those
based on 2MASS/MSX colors. These diagrams will enable the most luminous IR
sources in Local Group galaxies to be classified with high confidence based on
their Spitzer colors. Such characterizations of stellar populations will
continue to be possible during Spitzer's warm mission, through the use of IRAC
[3.6]-[4.5] and 2MASS colors.Comment: 31 pages, 10 figures, to be published in A
The potential for use of stormwater detention basins in the Las Vegas Valley for groundwater recharge
As an initial step in assessing the potential use of flood control detention basins in the Las Vegas Valley for stormwater harvest and groundwater recharge, a method for estimating precipitation on and runoff from watersheds tributary to detention basins was developed. Literature concerning geology, hydrogeology, stormwater quality, and subsurface water quality in the Las Vegas Valley, potential methods of stormwater harvest and groundwater recharge, and federal, state and local water quality regulatory requirements was obtained and evaluated in order to define the most favorable areas of the Las Vegas Valley for harvest and recharge. Based upon this review, the Red Rock Detention Basin was selected for trial application of a computerized implementation of a precipitation/runoff estimation procedure. The trial application indicated that over a representative 58-year period, the total potentially-harvestable stormwater resource available at the Red Rock Detention Basin would be 10,900 acre-feet
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