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  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 990-992 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have written and read bit patterns on arrays of square islands cut with a focused ion beam into granular perpendicular magnetic recording media. Using a static write–read tester, we have written square-wave bit patterns on arrays of islands with sizes between 60 and 230 nm, matching the recording linear density to the pattern period. These measurements reveal the onset of single-domain behavior for islands smaller than 130 nm, in agreement with magnetic force microscope images. The recording performance of patterned regions is systematically compared to that of unpatterned regions. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2748-2750 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have performed dynamic coercivity measurements on a series of antiferromagnetically coupled (AFC) magnetic recording media utilizing a static write/read tester. The samples consist of two magnetic layers, which are antiferromagnetically coupled by a nonmagnetic layer. The investigated samples have a fixed top layer thickness and variable bottom layer thickness, such that the composite remanent magnetization thickness product (MRtAFC) varies over a large range, 0.17–0.30 memu/cm2. We find that the ratio between anisotropy energy and thermal energy (≡ stability ratio, C−1), and the intrinsic switching field H0 are, within the experimental error, constant for the series. This suggests that the top magnetic layer to first order determines the stability ratio of the AFC media and that MRtAFC can be varied over a large range without decreasing the stability or increasing the write field requirements. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1505-1507 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The demagnetizing field across bit transitions in longitudinal recording media is measured quantitatively as a function of linear density using a quasi static write/read tester. Bit transitions with varying linear densities in the range 500–6000 flux changes per mm are recorded on CoCr10Ta4 media films. The media are deposited onto a coplanar waveguide structure, which is used to generate reversal field pulses of well-defined amplitude and 10 ns width to minimize thermally activated processes. The demagnetizing field is extracted from the measured reversal field, which is the sum of the external waveguide field and the internal, density-dependent demagnetizing field. The experimental results are qualitatively consistent with those predicted by a simple magnetostatic model that assumes finite transition widths. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 3409-3411 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have fabricated arrays of magnetic islands in perpendicular CoCrPt media with ∼100 nm lateral dimension using a focused ion beam. A quasistatic write/read tester was used to study aspects of the recording physics of these patterned media. We present results on the variation of the readback signal as the phase of the written square wave changes with respect to the patterned array as a function of island size and write current. Using an analytic near-field expression for head field we are able to model how the observed dependence between phase shift and readback signal as a function of write current arises. This analysis allows us to gain an insight into the role of the island switching field distribution and the write head magnetic field gradient in the patterned media writing process. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3806-3808 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We describe a magnetic recording media composed of antiferromagnetically coupled (AFC) magnetic recording layers as an approach to extend areal densities of longitudinal media beyond the predicted superparamagnetic limit. The recording medium is made up of two ferromagnetic layers separated by a nonmagnetic layer whose thickness is tuned to couple the layers antiferromagnetically. For such a structure, the effective areal moment density (Mrt) of the composite structure is the difference between the ferromagnetic layers allowing the effective magnetic thickness to scale independently of the physical thickness of the media. Experimental realizations of AFC media demonstrate that thermally stable, low-Mrt media suitable for high-density recording can be achieved. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Naturwissenschaften 24 (1936), S. 743-743 
    ISSN: 1432-1904
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
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  • 7
    ISSN: 0178-515X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract  A horizontal rotating tubular bioreactor (HRTB) is designed as the combination of a “thin layer bioreactor” and a “biodisc” reactor. The investigation of mixing in HRTB was done by the temperature step method in a wide range of process conditions [residence time (t z =360036000 s) and bioreactor rotation speed (n=0.0830.917 s−1)]. In all experiments heat losses were detected. A mathematical model based on “tank in series” concept was developed to describe the mixing in HRTB – a “spiral flow” model (SFM) which has incorporated heat losses. However, the simulations of SFM could be used for calculation of temperature response curves for the case when there is no heat losses. These corrected curves were used then to estimate Bodenstein number as a parameter of standard dispersion model (SDM). The obtained Bodenstein numbers were in the range 10–17. The simulations showed that SFM was more capable to describe the mixing in HRTB giving better fitting with experimental measurements than SDM, indicating that mixing pattern in HRTB is too complex to be described with this relatively simple, one-parameter model.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1573-2568
    Schlagwort(e): second messengers ; calcium ; trifluoperazine ; ionophore ; ion flux ; electrophysiology ; Ussing chamber
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Gallbladder absorption is increased prior to gallstone formation in prairie dogs and may promote cholesterol crystallization. Recent studies indicate that Ca2+-calmodulin (CaM) tonically inhibits gallbladder electrolyte absorption in prairie dogs fed a nonlithogenic diet. We hypothesized that dietary cholesterol alters CaM-dependent regulation of gallbladder ion transport, a possible link between increased gallbladder absorption and gallstone formation. Gallbladders from prairie dogs fed control (N = 24) or 1.2% cholesterol-enriched chow (N = 32) were mounted in Ussing chambers. Electrophysiology and ion flux were measured while exposing the epithelia sequentially to trifluoperazine (TFP), a CaM antagonist, followed by the calcium ionophore A23187. Animals fed the high cholesterol diet developed crystals and gallstones in a time-dependent fashion. Mucosal addition of 50 μM TFP decreased short-circuit current (Isc), transepithelial potential, and tissue conductance in control, crystal, and gallstone animals, but the magnitude of its effect was significantly decreased in animals fed cholesterol. TFP stimulated mucosa-to-serosa Na+ flux by 6.9 ± 0.9 μeq/cm2/hr in control animals but only 3.1 ± 0.8 μeq/cm2/hr in gallstone animals. Similarly, TFP increased mucosa-to-serosa Cl− flux by 11.9 ± 1.4 μeq/cm2/hr in controls but only 4.9 ± 1.4 μeq/cm2/hr in cholesterol-fed animals. TFP effects were not reversed by A23187, which caused differential effects on Isc and ion transport in cholesterol-fed animals. In conclusion, CaM-mediated inhibition of gallbladder Na+ and Cl− transport is diminished in prairie dogs fed cholesterol. We conclude that gallbladder ion transport is partially released from basal inhibition during gallstone formation and propose that dysfunctional CaM regulation may be a stimulus to increased gallbladder absorption.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1435-1463
    Schlagwort(e): Keywords:α-Dihydroergocryptine, voltage-gated sodium channels, (−)sulpiride, dopamine D2 receptor, dopamine outflow, neuroprotection.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary. Alpha-Dihydroergocryptine (α-DHEC), a Dopamine (DA) D2 receptor agonist, is widely used as dopaminergic drug in the treatment of Parkinson's disease. To study the mechanisms involved in the signal transduction process induced by α-DHEC on the presynaptic site of the dopaminergic neuron, we incubated slices of the rat caudate-putamen with α-DHEC and the indicated substances in static chambers. Following incubation the resulting DA outflow was measured by high-performance-liquid chromatography with electrochemical detection. The addition of α-DHEC (10 μM–0.1 mM) did not modulate basal DA outflow. Activation of voltage-gated sodium channels by veratridine (VER) from low to relatively high concentrations (1–10 μM) led to a concentration-dependent increase of DA outflow. Using concentrations as high as 10 μM a dramatic increase of DA levels (600% of baseline levels) was observed. The ability of VER to provoke DA release was sensitive to the addition of tetrodotoxin (TTX) and was completely blocked by 1 mM TTX. Coincubation of α-DHEC (10 μM–0.1 mM) and VER (10 μM) reduced VER-stimulated DA outflow in a concentration-dependent manner. The time-concentration course of VER-induced DA outflow was not modulated by α-DHEC. As described in our earlier studies, the specific D2 receptor antagonist (−)sulpiride (SLP) concentration-dependently enhances extracellular DA levels. Addition of α-DHEC almost completely blocked SLP-induced DA-outflow. When slices were incubated with the non-selective DA receptor agonist haloperidol (HLP, 0.1 mM) the effect of α-DHEC on VER-induced DA outflow was partially but not completely abolished. These data strongly suggest that the effect of α-DHEC on the presynaptic site implies an activation of D2 receptors as well as an inhibitory action on voltage-gated sodium channels. α-DHEC seems to modulate voltage-gated sodium channels in part independently from DA receptors since blockade of D2 receptors with saturating concentrations of haloperidol did not completely abolish its effect. Based on our data we have no evidence that voltage-gated potassium channels, N-type calcium channels or D1, D3-receptors are involved in the action of α-DHEC at the presynaptic site of the dopaminergic neuron. The results give one rationale for the proposed neuroprotective effect of α-DHEC
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 235-274 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A quite unconventional, innovative scientific methodology called “macroscopic pattern analysis” is presented in this paper. This approach is more adequate in the case of complex systems than the well-known microscopic, mechanistic approach. Complex systems are not only attracting more engineering interest, but their scientific treatment is increasingly wanted by society due to the manifold problems in Earth's ecosphere. The macroscopic pattern approach will be explained in depth and illustrated in some case studies from the ecosphere (sustainability, hurricanes and avalanches), where nature serves as a teacher for the solution of the sustainability problem. Then, a series of case studies on macropatterns are described showing the problem-solving capacity for anthropo- and technosphere: sustainability in society with an index of sustainability, the eco-social market economy with eco-tech as an instrument, biokinetics, bioreactor mixing and integrated bioprocessing with models, design of cars and houses and even quality of life as an attempt to quantify macropatterns.The innovations are briefly compared in their problem-solving capacity with known approaches such as the microscopic method in science, technology and society (free market economy), including the evaluation of other indices and cleaner production, industrial ecology and zero emission initiative. Finally, a deeper integration of sciences, ethics, arts and nature will be introduced based on the vision with macroscopic pattern analysis, where the different domains of human life are integratable to effect a reconciliation.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
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