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  • 1990-1994  (9)
  • 1985-1989  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Beam divergence effects on nonlinear frequency mixing (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1091-1101 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of the beam divergence of the input pump laser beams on the nonlinear frequency mixing process in a dielectric medium is discussed. The divergent laser beams have finite angular spreads so that all of the interactions between the two input beams can never satisfy the phase-matching condition exactly. A numerical model is developed to investigate the effects of input beam divergence on conversion efficiency. The angular spread of each of the input beams is represented by a set of plane waves having a distribution of propagation directions. Each of the plane-wave components from one input beam is allowed to interact with all the plane-wave components of the second input beam. This model is applicable to processes such as sum frequency generation, difference frequency generation, and optical parametric amplification. Second-harmonic generations as a special case of sum frequency generation is used as an example in the numerical studies. Results indicate that the conversion efficiency is dependent on the amount of beam divergence, the input intensity, and the length of the nonlinear medium. These parameters must be optimized with respect to one another to maximize the conversion. The optimization is especially critical in high-power systems where high conversion efficiency is sought.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351272
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics of optically pumped ZnHg (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1548-1555 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the various rates of formation and decay of ZnHg using a frequency doubled dye laser at 307.6 nm as a pump source for the zinc 3 P1 state. More specifically we have measured the rate of decay of the atomic 3 P1 state, the rate of three-body formation of excited ZnHg, the spontaneous emission coefficient of excited ZnHg, the rate of quenching of ZnHg by Hg atoms and the rate of biexcimer quenching. We have also carried out new measurements of the spectrum of excited ZnHg and of the intrinsic stimulated emission cross section.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457113
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    ECR ion and free radical sources for MBE applications : International conference on ion sources (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 282-284 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A small 2.45 GHz ion/free radical source that has been specifically designed for MBE applications is described. The overall outside diameter of this cylindrical source is 5.8 cm (includes magnets and applicator) and the length is less than 15 cm. Thus, it fits through vacuum ports on existing MBE machines and can be placed near the substrate. The microwave discharge, which is created within a cylindrical quartz tube, is surrounded by rare-earth magnets and a tunable coaxial cavity applicator. Single or double accelerating grids can be placed on the 3.75-cm-diam discharge output producing an ion beam, or the discharge can be freely exhausted into the vacuum allowing the charged and excited species to diffuse onto the substrate for plasma and/or free radical processing. This device can operate at pressures as low as 10−5 Torr with A, O2, and N2 gases using only 50–150 W of incident power. The detailed description and the preliminary experimental test of this source is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141322
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Two variants of transferrable extended-spectrum TEM-β-lactamase successively isolated from a clinical Escherichia coli isolate (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 93 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract In a leukaemic patient presenting a septicaemia treated with ceftrazidime and amikacin, two clinical Escherichia coli isolates distinguished by their level of resistance to oxyimino-β-lactams were isolated at an interval of 24 h. The isolates were identified by biotyping and esterase electrophoretic typing and the two host strains were shown to be identical. However, each of these strains exhibited a different transferrable extended-spectrum β-lactamase. These enzymes had different pl values (5.25 and 5.58), but were both blaTEM-1 mutants. The enzyme with pI 5.25 was identical to TEM-101 (TEM-12) (serine 162 substitution). The enzyme with pI 5.58 showed an additional amino acid substitution (lysine residue instead of an arginine at position 237) and was denominated TEM-23. These data indicate that point-mutations can be successively cumulated in vivo by blaTEM mutants, leading to expression of β-lactamases with increased hydrolysis rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05083.x
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  • 5
    Electronic Resource
    Electronic Resource
    Two novel transferable extended-spectrum β-lactamases from Klebsiella pneumoniae in Tunisia (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 67 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Two novel β-lactamases conferring multiresistance to antibiotics including oxyimino β-lactams have been identified in two nosocomial K. pneumoniae strains isolated in Tunis in 1986 and 1988. Both enzymes were encoded by ca. 150-kilobase plasmids. Donor and transconjugant strains producing these enzymes exhibited highly similar pattern of resistance (CTX phenotype) to β-lactams including penicillins and oxyimino β-lactams e.g. cefotaxime, ceftriaxone, ceftazidime, and aztreonam. High and variable synergy (16 to 1066-fold) was obtained when combined to 0.1 μg/ml of clavulance (β-lactamase inhibitor). The isoelectric points of these two enzymes were 5.4 and 6.4. These β-lactamases differed from TEM types by hydrolysis for cefotaxime or ceftriaxone but were inhibited by clavulanate and cloxacillin. DNA hybridization studies suggested that the genes of these enzymes may be derived from genes encoding TEM-type enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb13831.x
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    Paper (German National Licenses)
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  • 6
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    Elderly migration: For sun and money (1988)
    Amsterdam : Periodicals Archive Online (PAO)
    Population research and policy review. 7:2 (1988:May) 189 
    Details
    ISSN: 0167-5923
    Topics: Sociology
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:w515-1988-007-02-000005
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  • 7
    Electronic Resource
    Electronic Resource
    Almost periodic weak solutions to forced pendulum type equations without friction (1992)
    Springer
    Aequationes mathematicae 43 (1992), S. 313-313 
    Details
    ISSN: 1420-8903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01835716
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  • 8
    Electronic Resource
    Electronic Resource
    Almost periodic weak solutions to forced pendulum type equations without friction (1992)
    Springer
    Aequationes mathematicae 44 (1992), S. 100-108 
    Details
    ISSN: 1420-8903
    Keywords: Primary 34C27 ; Secondary 34C15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary We obtain sufficient conditions for the existence of almost periodic weak solutions to equations of the frictionless pendulum type with forcing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01834208
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  • 9
    Electronic Resource
    Electronic Resource
    Captopril induces correction of postrenal transplant erythremia (1990)
    Springer
    Transplant international 3 (1990), S. 222-225 
    Details
    ISSN: 1432-2277
    Keywords: Erythremia, post-transplantation ; Captopril, erythremia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Kidney transplant patients may develop post-transplant erythremia (PTE), and in order to avoid thromboembolism venesection, anticoagulation and native kidney removal have been suggested. We propose captopril as an alternative therapy for PTE. Seven hypertensive PTE patients, aged 42±10 years with stable renal function, were investigated to exclude primary or secondary polycythemia. All patients manifested true erythrocytosis [red blood cells (RBC) mass〉20% of predicted level] with concomitant increases in hematocrit and hemoglobin levels. Captopril was introduced in gradually increasing doses up to 75 mg/day under careful monitoring of blood pressure and renal function. Weekly follow-up was arranged to evaluate drug efficacy. After captopril, a significant reduction with normalization of the RBC mass (42±4 vs 31±5 ml/kg; P〈0.005) was observed. The RBC counts and hematocrit and hemoglobin levels also decreased. One patient had recurrent erythrocytosis after captopril withdrawal. Captopril may be a simple, effective, and non aggressive treatment for postrenal transplant erythremia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366970
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  • 10
    Electronic Resource
    Electronic Resource
    Ocular abnormalities associated with cutaneous melanoma and vitiligolike leukoderma (1986)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 224 (1986), S. 529-535 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several varieties of ocular pathology are associated with acquired cutaneous hypomelanosis (leukoderma; vitiligo). Our current study was undertaken to investigate the relationship between ophthalmologic disorders and a specific depigmentary phenomenon, the vitiligolike leukoderma of cutaneous melanoma. Over the past 14 years, eight patients with cutaneous melanoma and widespread areas of hypopigmentation were identified at the Pigmented Lesion Clinic of the Massachusetts General Hospital. The seven patients who underwent ophthalmologic examination had pigment-related ocular abnormalities. Among these were inflammations of the uveal tract in three patients, heterochromia in two, halo nevi of the choroid in one, and hypopigmentation and/or atrophy of the retinal pigment epithelium or choroid in four. Our findings demonstrate that ocular disease may be a component in a syndrome consisting also of cutaneous melanoma and vitiligolike leukoderma and suggest the need for complete ophthalmologic examinations in patients with melanoma and leukoderma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02154741
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