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  • 2005-2009  (1)
  • 2000-2004  (3)
  • 1990-1994  (7)
  • 1935-1939  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 512-514 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The third-order optical nonlinearity χ(3) of two novel guest-host polymers has been measured. The polymers consisted of nickel dithiolene guest molecules in a polymethylmethacrylate host and were prepared as cast or spun films. The optical nonlinearity was measured by degenerate four-wave-mixing experiments at a wavelength of 1.06 μm using 100-ps laser pulses. χ(3) coefficients of up to 10−17 m2/V2 were observed, corresponding to nonlinear refractive index n2 of up to 10−8 cm2/kW with a damage threshold (approximately-greater-than)1 GW/cm2.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 107-109 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The third-order optical nonlinearity χ(3), linear absorption coefficient α, and the two-photon absorption coefficient β of two nickel dithiolene complexes are reported. The nonlinearities were measured at 1064 nm using 100 ps pulses. Molecular nonlinearities 103 times those of carbon disulphide were observed. Two figures of merit were calculated from the data Δnsat/αλ=5 and n2/2βλ(approximately-greater-than)2, where α and β are the linear and two-photon absorption coefficients and n2 the nonlinear refractive index. These figures are compatible with those required for simple all-optical switching devices.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK and Malden, USA : Blackwell Science Ltd
    BJOG 112 (2005), S. 0 
    ISSN: 1471-0528
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Objective  To evaluate the effectiveness of a new handheld vacuum delivery device.Design  Randomised controlled trial.Setting  Southmead Hospital, Bristol, UK.Population  One hundred and ninety-four women requiring delivery with vacuum extraction.Methods  Women were recruited into the study while still in early labour. If during delivery, vacuum extraction was indicated they were then randomly allocated to either a new handheld vacuum device, the Kiwi Omnicup, or to a ‘standard’ vacuum cup selected by the obstetrician. The ‘standard group’ consisted of the silastic (66/98, 67%) or the metal cups (32/98, 33%). Study data were recorded at completion of the delivery and at 24–48 hours. An additional brief symptom questionnaire was completed by the mother at 10 days postnatally. Statistical analyses were done on an ‘intention-to-treat’ basis.Main outcome measures  The primary outcome was the successful completion of delivery with the allocated instrument. Secondary outcomes were substantial fetal scalp trauma and substantial maternal trauma.Results  The Omnicup was associated with a significantly higher failure rate than the standard cup [34%vs 21%, odds ratio (OR) = 1.9 (1.01–3.6)]. This difference persisted after adjusting for confounding factors [adjusted OR = 2.25 (1.01–5.0)] and resulted in significantly more forceps deliveries in the Kiwi Omnicup group [22%vs 10%, unadjusted OR = 2.5 (1.1–5.5)]. The caesarean section rates were similar in both groups [9.4%vs 8.2%, OR = 1.2 (0.4–3.2)]. Rates of substantial scalp trauma and maternal trauma were similar in both groups. However, there were more cases of jaundice in the standard cup group [2.3%vs 12.0%, unadjusted OR = 0.18 (0.04–0.82) and adjusted OR = 0.10 (0.01–0.88)].Conclusions  The Omnicup is not as successful at achieving a vaginal delivery as the combination of the currently used vacuum cups.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 150 (2004), S. 0 
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background  Optical coherence tomography (OCT) is a noninvasive morphological method for investigating human skin. It allows high-resolution in vivo imaging of inflammatory skin diseases and tumours. Because it is a newly developed method, systematic studies on standardization and on evaluation of factors influencing the representation of the skin have not yet been performed.Objectives  In this study, normal human skin was treated with various external stimuli which induce changes of function and morphology. Changes in stratum corneum thickness as well as changes induced by pigmentation, oedema and erythema were investigated using OCT.Methods  Healthy skin of human volunteers was treated with tape stripping, ultraviolet A irradiation, water, histamine, nicotinic acid and various ointments.Results  In the tape stripping experiment, the thickness of the horny layer was quantified and monitored. Pigmentation increased the light attenuation of the tissue, whereas hydration and erythema led to a slight decrease of scattering. Topical treatment of the skin gave a nonspecific increase of penetration depth of the light due to the lower reflectivity of the surface.Conclusions  There are various physiological conditions which influence optical properties of the skin. These parameters should be considered when performing standardized OCT studies.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Two-dimensional gel electrophoresis was used to follow low changes in gene expression associated with antibiotic (bialaphos) biosynthesis in Streptomyces hygroscopicus. Cultures were pulse-labelled with [35S]-methionine before, during, and after the switch from primary to secondary metabolism in order to compare kinetic profiles of bialaphos (antibiotic) production (bap) genes during this metabolic transition. Separation of gene products on two-dimensional gels revealed that 27 were dependent on brpA for optimal expression and were activated as the culture approached stationary phase. Genes which encoded 10 brp4-dependent proteins were mapped to a 10 kb Sstl fragment of the 35 kb bap gene cluster by expressing them in Streptomyces lividans using the thiostrepton-inducible tipA promoter. N-terminal amino acid sequences of two brpA-dependent proteins, obtained by direct microsequencing of protein spots excised from two-dimensional gels, identified them as gene products mapping to the same region and involved in secondary metabolic conversions of the bap pathway. The kinetics of synthesis of 16 brpA-dependent gene products were characterized using QUEST computer software. Cluster analysis performed on the kinetics of synthesis of 346 of the most highly expressed gene products of HP5-29, including 16 brpA-dependent ones, identified 75 families having distinct patterns of expression. Many brpA-dependent proteins were clustered together; 10 were found in one kinetic family. These kinetic families also included brpA-independent gene products perhaps subject to similar regulatory mechanisms and thus possibly involved in bialaphos biosynthesis. The activation/derepression of bap expression took place as cultures approached stationary phase and was temporally related to synthesis of ppGpp.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 1231-1233 
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 8
    facet.materialart.
    Unbekannt
    Philadelphia : Periodicals Archive Online (PAO)
    Social studies. 28:6 (1937:Oct.) 261 
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 1573-2665
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Optical and quantum electronics 22 (1990), S. 297-318 
    ISSN: 1572-817X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract Organic second-order nonlinear materials are currently receiving considerable attention for fabrication of frequency mixing and electro-optic devices. In this paper the key concepts in the development of organic nonlinear materials and waveguide device design are introduced. The recent advances in nonlinear waveguides for frequency doubling and electro-optic devices are reviewed.
    Materialart: Digitale Medien
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