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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1793-1803 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 86 (1979), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A central semen bank in Denmark supplied deep-frozen semen. Selection of donors, freezing technique, and practical details about transport of specimens are described. In one of the gynaecological departments supplied with frozen semen, 22 out of 30 patients who had artificial insemination became pregnant. The advantages and disadvantages of using frozen semen are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 86 (1979), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A successful pregnancy in a woman with Turner's syndrome with a 45, X/46,XX karyotype is described. The literature contains reports of a total of nine pregnancies in seven women with a 45,X karyotype and 56 pregnancies in 23 women with mosaicism and a 45,X cell line, as well as a 46,XX and/or 47,XXX cell line. Fifteen of the latter 56 pregnancies ended in spontaneous abortion (27 per cent), and four ended in the delivery of a stillborn child; 12 of the 37 liveborn infants (32 per cent) had a physical or mental abnormality, and 8 (22 per cent) had a chromosome abnormality. Three had Down's syndrome, and five had a 45,X cell line. Due to the relatively high (8 per cent) incidence of Down's syndrome among liveborn infants of women with Turner's syndrome, amniocentesis for fetal karyotyping should be advised.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 40 (1975), S. 593-598 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 708-710 
    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
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 97 (1975), S. 1184-1188 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 6518-6525 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microcanonical temperature is shown to be a useful concept in calculations of the decay of a small isolated system with well defined energy. A simpler and more transparent description is obtained than in Klots' formulation of finite-heat-bath theory, where the system is represented by a canonical ensemble. As a further illustration of the utility of the microcanonical temperature concept, we discuss a formula derived by Dunbar for the probabilities for excitation of a single oscillator in a collection of harmonic oscillators with well defined total energy. This formula expresses the excitation probabilities in terms of the temperature for a canonical ensemble with mean energy equal to the energy of the system. However, a much improved accuracy is obtained if the canonical temperature and heat capacity are replaced by their microcanonical values. We justify this replacement through a modified derivation, in which the microcanonical temperature appears as the canonical temperature of a fictitious system with level density ρ′(E), the derivative of the level density ρ(E) of the collection of oscillators. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of the study was to develop and evaluate different methods of double-blind, placebo-controlled food challenge (DBPCFC) with apple. Three different DBPCFC models were evaluated: fresh apple juice, freshly grated apple, and freeze-dried apple powder. All challenges were performed outside the pollen season and took place from 1997 to 1999. The freeze-dried apple material was characterized by means of leukocyte histamine release (HR), skin prick test (SPT), and immunoblotting experiments. The study population consisted of birch pollen-allergic patients with a history of rhinitis in the birch-pollen season and positive specific IgE to birch. For comparison of the DBPCFC models, 65 patients with a positive open oral challenge with apple were selected. In the characterization of the freeze-dried apple material, 46 birch pollen-allergic patients were included. The IgE reactivity to apple was evaluated by measurement of specific IgE, HR, and SPT. Golden Delicious apples were used in all experiments. The results of this study showed that it was possible to perform DBPCFC with apple in birch pollen-allergic individuals. The model with freshly squeezed apple juice had a low sensitivity and displayed a high frequency of reactions to placebo, probably due to the ingredients used for blinding. The sensitivity of the models with freshly grated apple and freeze-dried apple powder was 0.74/0.60. An increase in sensitivity is desirable. The freeze-dried apple powder proved to be useful for SPT, HR, and oral challenges, but further investigation of the stability and the allergenic profile of the material is needed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Allergy to hazelnuts is a common example of birch pollen related food allergy. Symptoms upon ingestion are often confined to the mouth and throat, but severe systemic reactions have been described in some patients. The aim of the study was to evaluate the reduction in allergenicity by roasting of the nuts.Methods: Double-blind, placebo-controlled food challenges (DBPCFC) with roasted hazelnuts (140°C, 40 min) were performed in 17 birch pollen allergic patients with DBPCFC-confirmed food allergy to raw hazelnuts. The effect of roasting was further evaluated by skin prick test (SPT), histamine release (HR), measurement of specific IgE, and IgE-inhibition experiments.Results: In 5/17 patients the DBPCFC with the roasted nuts were positive. The symptoms were generally mild and included OAS (oral allergy syndrome) in all patients. Roasting of the nuts significantly reduced the allergenic activity evaluated by SPT, HR, specific IgE, and IgE-inhibition. Immunoblotting experiments with recombinant hazelnut allergens showed sensitization against Cor a 1.04 in 16/17 patients and against Cor a 2 in 7/17 patients. None of the patients were sensitized to Cor a 8. Challenge-positive patients did not differ from the rest in IgE-binding pattern.Conclusions: All the applied methods indicated that roasting of hazelnuts reduces the allergenicity, but since 5/17 birch pollen allergic patients were DBPCFC-positive to the roasted nuts, ingestion of roasted hazelnuts or products containing roasted hazelnuts can not be considered safe for a number of hazelnut allergic consumers. For patients with a history of severe allergic symptoms upon ingestion of hazelnuts, thorough and conscientious food labelling of hazelnuts and hazelnut residues is essential.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Histopathology 44 (2004), S. 0 
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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