503 research outputs found
Birdcage resonator design in magnetic resonance imaging
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1995.Includes bibliographical references (p. 101).by Peter Sprenger.M.S
Kompetenzgrad von Lernenden beim Experimentieren im Geographieunterricht
Im Kompetenzbereich Erkenntnisgewinnung sollen Schüler_innen im Geographieunterricht den experimentellen Algorithmus durchlaufen, wobei vier Teilkompetenzen (Fragestellung formulieren, Hypothesen generieren, Experimente planen, Daten auswerten) im Vordergrund stehen. Ziel des Beitrags ist es, eine Aussage darüber zu treffen, über welchen Kompetenzgrad Schüler_innen beim Experimentieren im Fach Geographie tatsächlich verfügen. Bei der Erhebung wurden 662 Schüler_innen der Jahrgangsstufen 5-9 mit einem Messinstrument aus 29 Items befragt. Es handelt sich um ein deskriptives Design. Die Ergebnisse zeigen, dass sich das Kompetenzniveau der einzelnen Jahrgangsstufen unterscheidet. Darüber hinaus liegen spezifische Schwierigkeiten in allen Teilkompetenzen vor. Die Ergebnisse verdeutlichen, dass in allen Bereichen Förderbedarf besteht
Optimal Control Theory Techniques for Nitrogen Vacancy Ensembles in Single Crystal Diamond
Nitrogen Vacancy Center Ensembles are excellent candidates for quantum
sensors due to their vector magnetometry capabilities, deployability at room
temperature and simple optical initialization and readout. This work describes
the engineering and characterization methods required to control all four
Principle Axis Systems (P.A.S.) of NV ensembles in a single crystal diamond
without an applied static magnetic field. Circularly polarized microwaves
enable arbitrary simultaneous control with spin-locking experiments and
collective control using Optimal Control Theory (OCT) in a (100) diamond. These
techniques may be further improved and integrated to realize high sensitivity
NV-based quantum sensing devices using all four P.A.S. systems.Comment: 18 pages main text, 7 figures, 16 pages SI, 8 figures S
A coherent optical link through the turbulent atmosphere
We describe the realization of a 5 km free space coherent optical link
through the turbulent atmosphere between a telescope and a ground target. We
present the phase noise of the link, limited mainly by atmospheric turbulence
and mechanical vibrations of the telescope and the target. We discuss the
implications of our results for applications, with particular emphasis on
optical Doppler ranging to satellites and long distance frequency transfer.Comment: version 2, modified following comments from colleagues and reviewer
Raumanalyse mit virtuellen Exkursionen. Mit digitalen Medien Exkursionskonzepte zum Hafen Hamburg und zum Wald gestalten
In diesem Beitrag sollen die Raumbeispiele Hamburg Hafen und Wald multiperspektivisch mit Raumkonzepten erkundet werden. Als digitales Werkzeug wird ein Kartenprogramm (Padlet) mit verschiedenen Funktionen zur Gestaltung und Nutzung von Karten verwendet. Das Exkursionskonzept ist kollaborativ und virtuell angelegt. Zur Gestaltung der virtuellen Exkursion werden integrierte Bilder, Kurztexte und andere Medien genutzt, um der Frage nachzugehen, welche Bedeutung der Hafen in Hamburg bzw. der Wald fĂĽr unser Leben hat. (DIPF/Orig.
Sialic Acid Utilisation and Synthesis in the Neonatal Rat Revisited
Background: Milk is the sole source of nutrients for neonatal mammals and is generally considered to have co-evolved with the developmental needs of the suckling newborn. One evolutionary conserved constituent of milk and present on many glycoconjugates is sialic acid. The brain and colon are major sites of sialic acid display and together with the liver also of synthesis. Methodology/Principal Findings: In this study we examined in rats the relationship between the sialic acid content of milk and the uptake, utilization and synthesis of sialic acid in suckling pups. In rat milk sialic acid was found primarily as 39sialyllactose and at highest levels between 3 and 10 days postpartum and that decreased towards weaning. In the liver of suckling pups sialic acid synthesis paralleled the increase in milk sialic acid reaching and keeping maximum activity from postnatal day 5 onwards. In the colon, gene expression profiles suggested that a switch from sialic acid uptake and catabolism towards sialic acid synthesis and utilization occurred that mirrored the change of sialic acid in milk from high to low expression. In brain sialic acid related gene expression profiles did not change to any great extent during the suckling period. Conclusions/Significance: Our results support the views that (i) when milk sialic acid levels are high, in the colon this sialic acid is catabolized to GlcNAc that in turn may be used as such or used as substrate for sialic acid synthesis and (ii) when milk sialic acid levels are low the endogenous sialic acid synthetic machinery in colon is activated
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