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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3097-3099 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal stability of exchange-biased magnetic tunnel junctions is explored using near-edge x-ray absorption fine-structure spectroscopy. Structures with Ir–Mn antiferromagnetic exchange bias layers are much more thermally stable than similar structures with Fe–Mn exchange bias layers. In both cases, diffusion of Mn from the antiferromagnetic layer through thin exchange-biased ferromagnetic layers to the tunnel barrier is observed at elevated temperatures. This observation explains the diminished magnetoresistance of these structures on annealing even though the resistance of the tunnel junctions is hardly changed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Severe acute respiratory syndrome (SARS) has recently emerged as a new human disease, resulting globally in 435 deaths from 6,234 probable cases (as of 3 May 2003). Here we provide proof from experimental infection of cynomolgus macaques (Macaca fascicularis) that the newly discovered ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The technique used to align liquid crystals—rubbing the surface of a substrate on which a liquid crystal is subsequently deposited—has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The arrangement of spins at interfaces in a layered magnetic material often has an important effect on the properties of the material. One example of this is the directional coupling between the spins in an antiferromagnet and those in an adjacent ferromagnet, an effect first discovered ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 101-104 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Antiferromagnetic layers are a scientifically challenging component in magnetoelectronic devices, such as magnetic sensors in hard-disk heads, or magnetic random-access memory (RAM) elements. In this paper, it is shown that photoelectron emission microscopy (PEEM) is capable of determining the magnetic structure at the interface of ferromagnets and antiferromagnets with high spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized soft X-rays from a synchrotron source, give rise to a magnetic image contrast. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO3, microscopically resolving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO3 and an adjacent Co layer results in a complete correlation of their magnetic domain structures. From field-dependent measurements, a unidirectional anisotropy resulting in a local exchange bias of up to 30 Oe in single domains could be deduced. The elemental specificity and the quantitative magnetic sensitivity render PEEM a perfect tool to study magnetic coupling effects in multilayered thin-film samples.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Der Orthopäde 29 (2000), S. 342-352 
    ISSN: 1433-0431
    Keywords: Schlüsselwörter Metaphysäre Frakturen ; Osteoporose ; Frakturen beim alten Menschen ; Distale Radiusfrakturen ; Humeruskopffrakturen ; Femurfrakturen ; Key words Metaphyseal fractures ; Osteoporosis ; Elderly patients ; Fractures of the distal radius ; Fracutres of the proximal humerus ; Fractures of the femur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The most frequent localization of fractures in elderly patients are the metaphysis of the distal radius, the metaphysis of the proximal humerus and the metaphysis of the proximal femur. Displaced fractures of the distal radius should be reduced anatomically with a broad indication for surgery. A unilateral frame is the method of choice in multifragmentary and articular fractures although this procedure carries some disadvantages. Displaced proximal fractures of the head of the humerus should be reduced and fixed operatively. Minimal invasive procedures like tension band fixation lead to better results than fixation with plates. Non-reducible four-part fractures require primary prosthetic replacement. If standard procedures in the treatment of distal fractures of the humerus fail because of severe osteoporosis, tension band fixation may allow functional post-operative treatment. Fractures of the trochanteric region of the femur can be stabilized by several dynamic standard implants that permit early weight bearing. If fixations should fail, corrective osteotomies or changing of implants – in rate cases combined with bone cement – may be necessary. Each case requires an individualized procedure in order to ensure optimal restoration of function and mobility in elderly patients.
    Notes: Zusammenfassung Die häufigste Frakturlokalisation beim alten Menschen sind die Metaphyse des distalen Radius, des proximalen Humerus und des hüftgelenksnahen Femur. Bei Fehlstellungen am distalen Radius ist die anatomische Reposition anzustreben. Die Indikation zur operativen Stabilisierung ist großzügig zu stellen. Trotz gewisser Nachteile ist beim gelenknahen Trümmerbruch der Fixateur externe in schwierigen Fällen die Methode der Wahl. Am proximalen Humerus ist bei dislozierten Mehrsegmentfrakturen die operative Rekonstruktion indiziert. Wenig invasiven Methoden wie der Zuggurtungsosteosynthese ist der Vorzug zu geben. Wenn eine sinnvolle Rekonstruktion bei 4-Segmentfrakturen nicht möglich ist, ist die primäre Humeruskopfprothese indiziert. Wenn eine Standardversorgung bei distalen Humerusfrakturen wegen ausgeprägter Osteoporose scheitert, kann eine Zuggurtungsosteosynthese noch eine funktionelle Nachbehandllung ermöglichen. Bei per- und subtrochantären Frakturen stehen standardisierte dynamische Implantate zur Verfügung, die eine frühe Belastung ermöglichen. Beim Versagen von Implantaten können Umstellungsosteotomien, selten Verbundosteosynthesen oder ein Implantatwechsel erforderlich werden. Bei jedem Fall ist eine individuelle Entscheidung gefragt, die der Wiederherstellung von Belastung und Funktion beim älteren Patienten am ehesten gerecht wird.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 432 (2004), S. 885-888 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our knowledge of the structure of matter is largely based on X-ray diffraction studies of periodic structures and the successful transformation (inversion) of the diffraction patterns into real-space atomic maps. But the determination of non-periodic nanoscale structures by X-rays is much more ...
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In magnetic memory devices, logical bits are recorded by selectively setting the magnetization vector of individual magnetic domains either ‘up’ or ‘down’. In such devices, the fastest and most efficient recording method involves precessional switching: when a magnetic ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1084
    Keywords: Key words: Colon – CT – Three-dimensional CT – Virtual endoscopy – Image processing – Radiation exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pig's colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and “fly through” sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 48 (2000), S. 407-411 
    ISSN: 1432-0762
    Keywords: Key words Reproductive effort ; Testosterone ; Parental care ; Song rate ; House finch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Testosterone has been proposed to serve as the mediator that controls the relative effort that an individual male bird will devote to mating effort versus parental effort. Here, we demonstrate a testosterone-influenced trade-off between parental and mating efforts in male house finches. Male house finches with experimentally elevated testosterone fed nestlings at a significantly lower rate, but sang at a higher rate than males without manipulated testosterone levels. Females mated to testosterone-implanted males fed nestlings at a significantly higher rate than females mated to males without testosterone implants, resulting in similar feeding rates for both treated and untreated pairs. The effects of testosterone on male house finches, however, were not as dramatic as the effects of testosterone observed in some other socially monogamous species of birds. Because extra-pair copulations are uncommon in house finches and males provide substantial amounts of parental care, these more modest effects may be due to differences in how the allocation of reproductive effort affects the costs and benefits of different reproductive behaviors.
    Type of Medium: Electronic Resource
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