23,196 research outputs found
Axon fasciculation and differences in midline kinetics between pioneer and follower axons within commissural fascicles
Early neuronal scaffold development studies suggest that initial neurons and their axons serve as guides for later neurons and their processes. Although this arrangement might aid axon navigation, the specific consequence(s) of such interactions are unknown in vivo. We follow forebrain commissure formation in living zebrafish embryos using timelapse fluorescence microscopy to examine quantitatively commissural axon kinetics at the midline: a place where axon interactions might be important. Although it is commonly accepted that commissural axons slow down at the midline, our data show this is only true for leader axons. Follower axons do not show this behavior. However, when the leading axon is ablated, follower axons change their midline kinetics and behave as leaders. Similarly, contralateral leader axons change their midline kinetics when they grow along the opposite leading axon across the midline. These data suggest a simple model where the level of growth cone exposure to midline cues and presence of other axons as a substrate shape the midline kinetics of commissural axons
Analysis of impact of Busch Gardens expansion on air quality of surrounding area
This report is concerned primarily with the increase in carbon monoxide concentrations and hydrocarbon concentrations induced by the projected increased traffic that would be associated with the parking facilities planned to support the expansion of Busch Gardens (Virginia) planned for the summar of 1976. Of primary concern is the integrated effect of the increased traffic that will be handled by existing facilities and an enlarged parking lot across the highway from the main Busch Garden attraction
Variations of the Lifshitz-van der Waals force between metals immersed in liquids
We present a theoretical calculation of the Lifshitz-van der Waals force
between two metallic slabs embedded in a fluid, taking into account the change
of the Drude parameters of the metals when in contact with liquids of different
index of refraction. For the three liquids considered in this work, water,
and the change in the Drude parameters of the metal imply a
difference of up to 15% in the determination of the force at short separations.
These variations in the force is bigger for liquids with a higher index of
refraction.Comment: 2 figures, 1 tabl
CMS dashboard task monitoring: A user-centric monitoring view
We are now in a phase change of the CMS experiment where people are turning more intensely to physics analysis and away from construction. This brings a lot of challenging issues with respect to monitoring of the user analysis. The physicists must be able to monitor the execution status, application and grid-level messages of their tasks that may run at any site within the CMS Virtual Organisation. The CMS Dashboard Task Monitoring project provides this information towards individual analysis users by collecting and exposing a user-centric set of information regarding submitted tasks including reason of failure, distribution by site and
over time, consumed time and efficiency. The development was user-driven with physicists invited to test the prototype in order to assemble further requirements and identify weaknesses with the application
Microstructure and mechanical properties of bulk yttria-partially-stabilized zirconia
A commercially available bulk 4.5 mole percent yttria-(Y2O3) partially stabilized zirconia (PSZ) was studied by light microscopy, X-ray analysis, microhardness measurement, and fracture toughness testing. The growth of the precipitates and the phase transformations were studied as a function of aging in air at 1500 C. Aging curves were constructed for both the as received and the solution annealed and quenched materials; the curves showed hardness peaks at 1397 and 1517 Kg/sq mm respectively. The rectangular plate shaped tetragonal precipitates were found to have a 110 habit plane. A total of twelve different types of tetragonal precipitates were found. Grinding of the Y2O3 PSZ into powder did not cause a significant amount of metastable tetragonal precipitates to transform into the monoclinc phase, thus indicating that transformation toughening is not a significant mechanism for the material
Some effects of the Atlantic circulation and of river discharges on the residual circulation of the North Sea
In a previous paper the simulation of the tidal and wind generated mean residual circulation in the North Sea was studied, with special references to pollution problems. In that paper, the influence of the Atlantic circulation on the North Sea has been neglected. Referring to the above mentioned paper, in this study the net inflow via the Dover Strait, Kattegat and rivers is simulated in the model. The model runs were repeated, yielding a significant improvement in comparison with observed data. © 1979 Deutsches Hydrographisches Institut
Attachment working models as unconscious structures: An experimental test
Internal working models of attachment (IWMs) are presumed to be largely unconscious representations of childhood attachment experiences. Several instruments have been developed to assess IWMs; some of them are based on self-report and others on narrative interview techniques. This study investigated the capacity of a self-report measure, the Inventory of Parent and Peer Attachment (IPPA; Armsden & Greenberg, 1987), and of a narrative interview method, the Adult Attachment Interview (AAI; George, Kaplan, & Main, 1985), to measure unconscious attachment models. We compared scores on the two attachment instruments to response latencies in an attachment priming task. It was shown that attachment organisation assessed by the AAI correlates with priming effects, whereas the IPPA scales were inversely or not related to priming. The results are interpreted as support for the assumption that the AAI assesses, to a certain degree, unconscious working models of attachment
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