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  • 1
    ISSN: 1432-0649
    Keywords: PACS: 42.50.Vk, 42.82.Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 6 plasma. We show that the result can be an array of parallel wires as narrow as 68 nm or an array of parallel Si trenches as narrow as 85 nm. The laser-focused deposition process is inherently parallel, so a large area is patterned simultaneously with an accurate periodicity of 212.78 nm. This method represents a novel way to make large, coherent arrays of sub-100 nm-size structures.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1084
    Keywords: Key words: Pulseless disease ; Aortitis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9–12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 137 (1995), S. 74-77 
    ISSN: 0942-0940
    Keywords: Blood flow velocities ; tanscranial Doppler ; meningitis ; CSF pleocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Serieal transcranial doppler studies were carried out in 12 patients, who developed meningitis during their hospital stay. Blood flow velocities in large basal vessels of the anterior circle of Willis were correlated with CSF pleocytosis and CSF sugar values. Mean blood flow velocities were found to be directly proportional to the CSF white blood cell (WBC) count and were inversely proportional to the CSF sugar values. Blood flow velocities were higher when CSF WBC count was raised. With only one exception these velocities decreased progressively with a fall in the CSF WBC count. At the time of meningitis there occurred a reduction in CSF sugar values and the blood flow velocities were significantly higher. With increase in CSF sugar values there occurred a gradual fall in the blood flow velocities.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3730-3738 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the nature of the solid-state amorphization induced by mechanical deformation (ball milling) in the case of the Fe2Ti phase [mechanical milling (MM)] and that of the iron and titanium phases mixed in the atomic proportion Fe67Ti33 [mechanical alloying (MA)]. Neutron and x-ray diffraction, combined with Mössbauer spectroscopy at room temperature, of samples mechanically treated for different times indicate that the MM of the Fe2Ti compound leads to a highly fragmented and disordered (micro)crystalline phase. No changes of the Fe2Ti (MgZn2-type) structure are observed in the mechanically and thermally treated Fe2Ti alloys. Conversely, the MA of the pure elements shows a partial amorphization reaction. The chemical short-range order observed in the neutron-diffraction data indicates that a true alloying of the elements occurs. In addition, the thermograms of the MA specimens are different from those of the equivalent MM products. In fact, the phases observed after annealing at 600 °C of the specimens MA 2 and 4 h are a mixture of α-iron and of disordered Fe–Ti intermetallic. A fully amorphous structure is obtained after annealing the samples MA treated for 8 and 16 h. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6274-6278 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The wet chemical treatment using SeS2 is an inexpensive and simple method of depositing selenium on GaAs surfaces. This treatment improves the electronic properties of the surface as seen from the increase in photoluminescence intensity. We present our results on surface structural investigations of GaAs(110) surface passivated by SeS2 treatment using atomic force microscopy. Our results show that SeS2 treatment can passivate the GaAs(110) surface forming ordered overlayers on it. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 50 (1995), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Somatosensory evoked potentials were recorded in 20 healthy volunteers and 20 patients with chronic pain undergoing electro-acupuncture therapy. The values of absolute peak latency and amplitudes of N19 and P22 in the control group were compared with the corresponding baseline values in the study group and after electro-acupuncture therapy at three stages during a 10-treatment cycle. On these occasions the intensity of pain was recorded using a 100 mm visual analogue scale score. Each patient in the study group had 10 treatments given on alternate days. The absolute peak latency of N19 was significantly delayed (p 〈 0.05) in chronic pain patients when compared to the control group. This increase in latency of N19 persisted after the first electro-acupuncture treatment (p 〈 0.05), tended to revert to normal after the fifth treatment (p 〉 0.05) and reverted completely to control values after the 10th treatment (p 〉 0.05). Visual analogue scores also decreased significantly (p 〈 0.05) after the fifth and 10th electro-acupuncture sessions. These observations suggest that there is an interaction of the neural mechanisms of electro-acupuncture with the thalamic generator of somatosensory evoked potentials i.e. N19.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Haemophilia 3 (1997), S. 0 
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Chronic liver disease has affected a majority of haemophiliacs exposed to factor VIII and factor IX concentrates before effective viral attenuation techniques were introduced. Progressive hepatitis and liver failure have increasingly become causes of morbidity, especially in haemophilia patients also seropositive for HIV. Encouraging reports of recombinant alpha interferon to reverse the histological, laboratory and clinical deterioration of chronic active hepatitis justifies obtaining liver biopsies to assess the severity of liver damage; however, the percutaneous method carries a significant risk of bleeding. Therefore, we employed a transjugular venous approach for liver biopsies in six HCV-, HBSAb- and HIV-seropositive adults with severe haemophilia A (n = 5) or B (n = 1) with persistent liver function abnormalities. Adequacy of the specimens and lack of haemorrhagic complications leads us to conclude that this procedure appears to be safe and effective in individuals with severe haemophilia or other congenital or acquired coagulopathies.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6079-6083 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nanostructured materials and devices will play an important role in a variety of future technologies, including magnetics. We describe a method for nanostructure fabrication based on the use of laser light to focus neutral atoms. The method uses neither a mask nor a resist, but relies on the direct deposition of atoms to form permanent structures. Since the atomic de Broglie wavelength is of picometer order, the size of structures produced is not significantly limited by diffraction, as in optical lithography. Lines as narrow as 38 nm full width at half maximum spaced by 213 nm have been produced and we have demonstrated the production of a two-dimensional array of dots. The highly parallel process of nanostructure formation and the intrinsic accuracy of the optical wavelength that determines structure spacing suggest a number of interesting applications, including calibration standards for various types of microscopy, lithography, and micromeasurement systems. Possible magnetic applications include the production of arrays of magnetic elements, laterally structured giant magnetoresistive devices, and the patterning of magnetic media.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 10 (1998), S. 437-456 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural features of turbulence at the free surface of a channel flow have been experimentally investigated. The experiments were conducted in a horizontal channel of large aspect ratio in the (depth based) Reynolds number range of 2800–8800. The results indicate that the persistent structures on the free surface can be classified as upwellings, downdrafts, and spiral eddies. Upwellings are shown to be related to the bursts originating in the sheared region at the channel bottom and the eddies are seen to be generated at the edges of the upwellings. The eddies often merge if rotating in the same direction, and form "pairs" if rotating in opposite directions—though there are occasional mergers of such counter-rotating ones. The spiral eddies decay slowly and are sometimes annihilated by fresh upwellings. The population densities and the persistence times of the various structures were measured for different flow conditions. The resulting data show that the physical parameters characterizing the structures at the interface, scale with a mix of inner (wall shear stress and viscosity) and outer variables. Measurement of the streamwise and spanwise velocities at the free-surface were made by particle imaging velocimetry (PIV) and the surface normal velocity near the free-surface estimated by continuity. The results indicate that the upwellings and spiral eddy regions would be expected to dominate scalar transport rates at high Prandtl/Schmidt numbers. The one-dimensional energy spectra of the flow field at the free-surface compare well with direct numerical simulations and show a region with −5/3 slope at low wave numbers. This experimentally confirms a previous result regarding the two-dimensionality of turbulence near the free surface, based on numerical simulations by Pan and Banerjee [Phys. Fluids 7, 1649 (1995)]. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3602-3610 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple, noncontact technique for the measurement of thermal diffusivity of solids is experimentally demonstrated. The technique is based on the photothermal displacement effect. Excellent agreement between the quasistatic theory of photothermal displacement and the experiment has been obtained. The technique has been demonstrated by measuring the thermal diffusivities of GaAs and InGaAs/AlGaAs multiple quantum wells. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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