3,466 research outputs found
Orbiter windward surface entry Heating: Post-orbital flight test program update
Correlations of orbiter windward surface entry heating data from the first five flights are presented with emphasis on boundary layer transition and the effects of catalytic recombination. Results show that a single roughness boundary layer transition correlation developed for spherical element trips works well for the orbiter tile system. Also, an engineering approach for predicting heating in nonequilibrium flow conditions shows good agreement with the flight test data in the time period of significant heating. The results of these correlations, when used to predict orbiter heating for a high cross mission, indicate that the thermal protection system on the windward surface will perform successfully in such a mission
The Splenic Microvasculature of the Red-Eared Turtle (Chrysemys scripta elegans): A Study Concerning the Question Whether the Circulation is Anatomically Open or Closed
The splenic microvasculature of the turtle Chrysemys scripta elegans was studied by means of scanning electron microscopy of vascular corrosion casts and critical point dried tissue. In addition light- and transmission electron microscopic investigations were carried out. Within the organ the arteries are surrounded by periarterial lymphoid sheaths. The majority of the arterial capillaries, which emerge from these central arteries have open endings within the reticular meshwork of the red pulp. Approximately 10% of the capillaries directly connect with the venous origins. Since these venous capillaries of C. scripta elegans resemble those of nonsinusal mammalian spleens we termed them pulp venules.
Several blood cells were seen in passage through the fenestrae of the pulpvenules. The blood cells overcome these wall pores either unimpeded or a striking deformation of the passing cell occurs.
In the subcapsular region of the organ radially arranged venous vessels are observed, which drain into a collecting vein
Absolute calibration of the LOPES antenna system
Radio emission in extensive air showers arises from an interaction with the
geomagnetic field and is subject of theoretical studies. This radio emission
has advantages for the detection of high energy cosmic rays compared to
secondary particle or fluorescence measurement methods. Radio antennas like the
LOPES30 antenna system are suited to investigate this emission process by
detecting the radio pulses. The characteristic observable parameters like
electric field strength and pulse length require a calibration which was done
with a reference radio source resulting in an amplification factor representing
the system behavior in the environment of the KASCADE-Grande experiment.
Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is
calibrated absolutely for systematic analyses of the radio emission.Comment: 5 pages, Proceedings of International Workshop on Acoustic and Radio
EeV Neutrino detection Activities: ARENA, May 17-19, 2005, DESY Zeuthe
Compounds from fermented noni exudates (fNE) selectively kill human cancer cells
Our recent studies involving fermented noni exudates (fNE) made from noni (Morinda citrifolia) have shown promising anti-cancer activities. Using an in vitro cell culture system, this study examines dozens of compounds isolated from fNE in order to identify specific compounds preferentially toxic to tumor cells. The compounds at concentrations of 20, 5, or 2 μg/ml were added to NL-20 non-tumor lung cells or A549 lung carcinoma cells and incubated for 48 hours. The cytotoxicity of the compounds on the cells was measured using the MTS cell proliferation assay. Several compounds were found selectively effective in killing more A549 tumor cells than NL-20 cells. An antioxidant assay was then performed to investigate if a correlation exists between antioxidant activity and selective cancer cell killing in our samples. We found that samples BGS, C2, BGL, and C1 had the highest amount of antioxidant activity. Of these samples, only C2 showed significant selective A549 cell killing (p\u3c.05 at 2μg/ml). Further testing is necessary to determine the mechanism of action and its possible role in immune activation
Low-energy electron scattering from methanol and ethanol
Measured and calculated differential cross sections for elastic (rotationally unresolved) electron scattering from two primary alcohols, methanol (CH3OH) and ethanol (C2H5OH), are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°–130°. There are no previous reports of experimental electron scattering differential cross sections for CH3OH and C2H5OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well
Supporting induction: relationships count
This article examines the structural changes to the induction of teachers in Scotland using the perceptions of a group of final year student teachers. This group would be the first probationer teachers to experience revised arrangements for new teacher induction in 37 years. Their preferences and concerns are highlighted, as the new procedures roll out in schools nationwide, in an attempt to stress the importance of relationships to the success of the induction scheme. The argument put forward in this article is based on the notion that personal intelligence is central to effective relationships and therefore crucially important in the context of this mentoring relationship. The views of our sample provide evidence to suggest that the quality of interactions between the mentor and the probationer teacher are paramount in providing a good induction experience. These views are substantiated by experiences in England and in induction literature elsewhere. A synthesis of this evidence is used to make recommendations for those involved in supporting induction in schools, local authorities or teacher education institutions
Course-based Science Research Promotes Learning in Diverse Students at Diverse Institutions
Course-based research experiences (CREs) are powerful strategies for spreading learning and improving persistence for all students, both science majors and nonscience majors. Here we address the crucial components of CREs (context, discovery, ownership, iteration, communication, presentation) found across a broad range of such courses at a variety of academic institutions. We also address how the design of a CRE should vary according to the background of student participants; no single CRE format is perfect. We provide a framework for implementing CREs across multiple institutional types and several disciplines throughout the typical four years of undergraduate work, designed to a variety of student backgrounds. Our experiences implementing CREs also provide guidance on overcoming barriers to their implementation
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The role of organizational climate in socially embedding construction firms’sustainability goals
Despite the growing interest in sustainability research, little scholarly attention, both conceptual and empirical, has been given to assessing the individual-level behavioural issues that affect sustainability outcomes. Still less research is undertaken to examine the mechanisms by which construction firms enable their sustainability goals to be socially embedded within their organizations to shape the behaviour and attitudes of employees. In an attempt to fill this gap, this paper draws from the extensive literature on organizational climate perspective to explain how organizational-level characteristics and processes can result in a strong, conducive climate that fosters shared perceptions and guide behaviours that are fundamental to the attainment of sustainability goals in organizations. From the critical review of this literature, this paper offers three research propositions and avenues in which they could be tested. The paper concludes with a broadened discussion of the theoretical and practical implications this framework has on advancing the sustainability discourse within CM discipline beyond the current largely technical, policy and institutional foci
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