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  • 2000-2004  (14)
  • 1995-1999  (22)
  • 1985-1989  (17)
  • 1980-1984  (19)
  • 1940-1944  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Numerical calculation of axisymmetric electrostatic modes for cold finite-length non-neutral plasmas (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2630-2639 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A numerical calculation of mode frequencies for cold, non-neutral plasmas is reported. The numerical method can be applied to any axisymmetric plasma shape in a trap. Here, it is used to study axisymmetric electrostatic modes in a long conducting cylinder. These modes were previously studied by Prasad and O'Neil [Phys. Fluids 26, 665 (1983)] and by Dubin [Phys. Rev. Lett. 66, 2076 (1991)]. In contrast to Dubin's calculation, the effects of a nearby cylindrical wall, including its influence on the shape of the plasma equilibrium, are considered. It is found that for plasmas with aspect ratios (length divided by diameter) near unity the numerical results can be approximately obtained by judiciously combining Dubin's calculation, and the Trivelpiece–Gould dispersion relation for infinitely-long geometry. For aspect ratios larger than about three, the Trivelpiece–Gould dispersion relation can be used in a simple way to obtain the numerically-computed mode frequencies with an accuracy of 1%, or better. The potential use of this calculation as a plasma diagnostic is also discussed, and it is argued that at the present level of accuracy (1–2%) its usefulness is marginal, but that an improvement by an order of magnitude might make it more interesting. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871228
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  • 2
    Electronic Resource
    Electronic Resource
    Fast and accurate current-voltage curves of metallic quantum point contacts (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1793-1803 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present an experimental setup for measuring the electrical conductance through metallic quantum point contacts (QPCs) under constant or time-dependent bias voltage conditions. The response time of the setup is as short as 25 ns and typical bias voltages range from 10 mV to 2 V. A function generator is used as bias voltage supply. With this, voltage bursts with a frequency of up to 100 kHz can be applied to the QPCs, whereby current-to-voltage (I–V) curves can be acquired using a homebuilt, 30 MHz bandwidth I–V converter, and a 100 Msamples/s digital storage oscilloscope. Test experiments on resistors show that nonlinear contributions to the I–V curves are always less than 1% of the current for all applied voltages. From the slope of the I–V curves, the conductance can be determined with an accuracy better than 1%. The QPCs are formed between a single-crystal metal sample and the tip of a scanning tunneling microscope under clean ultrahigh vacuum conditions. We demonstrate how the setup can be used to capture the I–V curves of several metastable states in a Au QPC, as it breaks during a period of 200 μs at room temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150539
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  • 3
    Electronic Resource
    Electronic Resource
    Submicrometer-resolution photoelectron-spectroscopy at MAX Lab : INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2168-2171 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a photoemission microprobe beamline at the MAX laboratory is presented. The beamline will utilize the radiation from a 26 period undulator on the 550-MeV MAX storage ring. The beamline will be capable of providing about 1010 photons/s of monochromatized radiation (bandwidth better than 0.25 eV) in the energy range of 20 to 150 eV focused into a submicrometer focal spot. It will be used for scanning photoemission experiments with a lateral resolution better than 1 μm. The optical system is comprised of a plane-grating monochromator with a Kirkpatrick–Baez objective and a specially designed ellipsoidal focusing mirror.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140812
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  • 4
    Electronic Resource
    Electronic Resource
    Electronics for microchannel photomultipliers in the LIDAR Thomson scattering diagnostic on JET (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 3265-3269 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The electronics for the microchannel plate photomultiplier tubes used in the LIDAR (Light Detection and Ranging) Thomson scattering diagnostic on the JET tokamak are described. It is shown how the microchannel plate photomultiplier tubes are gated with a very small coupling between gate signal and output, and how ≈300 V transient pulses with rise times of 230 ps are clipped to safe levels of ≈40 V.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140563
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  • 5
    Electronic Resource
    Electronic Resource
    The LIDAR Thomson scattering diagnostic on JET (invited) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1451-1456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3-J pulse energy, 300-ps pulse duration, 0.5-Hz repetition rate) together with a 700-MHz bandwidth detection and registration system yields a spatial resolution of about 12 cm. A spectrometer with six channels in the wavelength range 400–800 nm gives a dynamic range of the temperature measurements of 0.3–20 keV. The stray light problem in the backscatter geometry is overcome by spectral discrimination and gating of the photomultipliers. A ruby filter in the spectral channel containing the laser wavelength allows calibration of the vignetting along the line of sight by means of Raman scattering, enabling the measurement of density profiles. The low level of background signal due to the short integration time for a single spatial point yields low statistical errors (ΔTe /Te ≈6%, Δne /ne ≈4% at Te =6 keV, ne =3×1019 m−3 ). Goodness-of-fit tests indicate that the systematic errors are within the same limits. The system is described and examples of measurements are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139686
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  • 6
    Electronic Resource
    Electronic Resource
    Spontaneous abortion following mid-trimester amniocentesis. Clinical significance of placental perforation and blood-stained amniotic fluid (1987)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 94 (1987), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The clinical significance of placental perforation and bloodstained amniotic fluid was studied in a group of 7238 Danish women undergoing mid-trimester amniocentesis for prenatal diagnosis under ultrasound guidance. The risk of spontaneous abortion was significantly increased both in pregnancies where the placenta was perforated and in those with blood-stained amniotic fluid. The risk estimate nearly doubled after placental perforation and more than doubled with a bloody tap. It is concluded that for women at relatively low risk of a fetal genetic abnormality, the indication of the amniocentesis should be reconsidered if a placental perforation is unavoidable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1987.tb02252.x
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  • 7
    Electronic Resource
    Electronic Resource
    Current-voltage curves of gold quantum point contacts revisited (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 708-710 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present measurements of current–voltage (I–V) curves on gold quantum point contacts (QPCs) with a conductance up to 4 G0 (G0=2e2/h is the conductance quantum) and voltages up to 2 V. The QPCs are formed between the gold tip of a scanning tunneling microscope and a Au(110) surface under clean ultra-high-vacuum conditions at room temperature. The I–V curves are found to be almost linear in contrast to previous reports. Tight-binding calculations of I–V curves for one- and two-atom contacts are in excellent agreement with our measurements. On the other hand, clearly nonlinear I–V curves are only observed when the sample has been cleaned in air. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.127093
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  • 8
    Electronic Resource
    Electronic Resource
    Glutaraldehyde occupational dermatitis (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Contact dermatitis 9 (1983), S. 0 
    Details
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0536.1983.tb04639.x
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  • 9
    Electronic Resource
    Electronic Resource
    Radiative cooling of fullerenes (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 5012-5018 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the metastable fragmentation of fullerene ions in molecular beams. The rates are significantly smaller than the evaporative ensemble prediction, consistent with an alternative cooling mechanism through emission of electromagnetic radiation. Modeling the competition between radiative and evaporative cooling yields information about the evaporative activation energy and emissivity of the carbon clusters. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471130
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  • 10
    Electronic Resource
    Electronic Resource
    Icosahedra of icosahedra: The stability of (C60)13 (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 6088-6089 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The relative stability of clusters of fullerenes has been investigated. By heating the clusters before ionization we have obtained mass spectra where only the monomer and (C60)13 are present in significant amounts. An approximately 20% increase of the activation energy for evaporation of a monomer from (C60)13 compared to that from (C60)14 explains the experimental results. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472448
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