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  • 1
    Electronic Resource
    Electronic Resource
    Two- and three-body forces in the interaction of He atoms with Xe overlayers adsorbed on (0001) graphite (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 6477-6493 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to address the problem of three-body interactions in gas–surface scattering, we considered the collision of a He atom with the (0001) surface of graphite coated by a monolayer of Xe. To eliminate the uncertainties connected with errors in the two-body He–Xe interaction, we determined the latter by crossed-beam differential collision cross-section measurements performed at two energies (67.2 and 22.35 meV). These scattering data together with room-temperature bulk diffusion data are then fitted with a Hartree–Fock–dispersion–type function to yield an interaction potential that explains most of the properties of this system within the experimental errors and represents an improvement on previously published He–Xe potentials. Helium diffraction measurements are then carried out from the Xe overlayer and the dependence of the specular intensity from the angle of incidence is carefully determined. Further, a He–surface potential is constructed by adding together the following terms: (1) the He–Xe pairwise sum, (2) the long-range He–(0001)C interaction, (3) the three-body contribution generated by the Axilrod–Teller–Muto term, (4) the so-called surface-mediated three-body interaction He–Xe–(0001)C first considered by A. D. McLachlan [Mol. Phys. 7, 381 (1964)], and finally (5) a small correction which is meant to take into account the nonstationary nature of the surface. Using this potential, well-converged close-coupling scattering calculations are carried out, and their results compared with the data. In general, good agreement is obtained. The agreement can, however, be improved by (a) an increase of about 30% in the contribution of three-body forces, (b) the lowering of the He–graphite long-range attraction coefficient by about 15%, or (c) a reduction of the two-body interaction well depth of 1.6% (the experimental error) together with any combination of the factors under (a) and (b) reduced by an adequate amount. Elimination of the contribution of the graphite surface by studying Xe multilayers is hindered by the uncertainties in the "thermal correction'' [point (5) above] which, due to the multilayer increased "softness,'' becomes an appreciable source of uncertainty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457364
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  • 2
    Electronic Resource
    Electronic Resource
    Local linearization stability (1987)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 1844-1847 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is shown that Einstein's equations are always linearization stable around any finite region of space-time. Let (Ω,g0ab ) be any region of space-time, admitting a compact Cauchy surface with nonempty smooth boundary, and with g0ab a sufficiently smooth solution of the vacuum Einstein equation. It is shown that for any solution g1ab of the linearized equation and any open region U⊆Ω, there exists a smooth one-parameter family gλab of solutions on U such that (gλab||λ=0 =g0ab ) ||U and ((d/dλ)gλab =g1ab )||U. By using a result of Choquet-Bruhat and York [The Cauchy Problem, General Relativity and Gravitation, edited by A. Held (Plenum, New York, 1980), Vol. 1] asserting the smoothness of the map that sends initial data into solutions of Einstein's evolution equations the proof of the above theorem is reduced to the proof of a similar theorem for Einstein's constraint equations. The proof of this latter theorem involves the use of the implicit function theorem in Hilbert spaces. This local result on linearization stability asserts, in contrast to the general global case, that linearization about any vacuum solution is locally physically meaningful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.527445
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  • 3
    Electronic Resource
    Electronic Resource
    Multimodal impurity redistribution and nanocluster formation in Ge implanted silicon dioxide films (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3215-3217 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The depth distribution of Ge implanted into thermally grown SiO2 films has been studied after annealing using transmission electron microscopy, Rutherford backscattering spectrometry, and x-ray diffraction. At annealing temperatures above 900 °C a significant redistribution of the as-implanted Ge profile was found. Crystalline Ge nanoclusters embedded in the SiO2 matrix are formed within a cluster band with well defined boundaries. The evolution of nanoclusters can be explained qualitatively by a model based on nucleation, growth and Ostwald ripening of Ge precipitates. Besides, chemical and interface reactions lead to the formation of additional Ge peaks near the surface and at the Si/SiO2 interface. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120294
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  • 4
    Electronic Resource
    Electronic Resource
    State-selective control for vibrational excitation and dissociation of diatomic molecules with shaped ultrashort infrared laser pulses (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 1862-1879 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ultrafast state-selective dynamics of diatomic molecules in the electronic ground state under the control of infrared picosecond and femtosecond shaped laser pulses is investigated for the discrete vibrational bound states and for the dissociative continuum states. Quantum dynamics in a classical laser field is simulated for a one-dimensional nonrotating dissociative Morse oscillator, representing the local OH bond in the H2O and HOD molecules. Computer simulations are based on two approaches — exact treatment by the time-dependent Schrödinger equation and approximate treatment by integro-differential equations for the probability amplitudes of the bound states only. Combination of these two approaches is useful to reveal mechanisms underlying selective excitation of the continuum states and above-threshold dissociation in a single electronic state and for designing optimal laser fields to control selective preparation of the high-lying bound states and the continuum states. Optimal laser fields can be designed to yield almost 100% selective preparation of any prescribed bound state, including those close to the dissociation threshold. State-selective preparation of the highest bound state may be accompanied by the appearance of a quasi-bound molecular state in the continuum with the kinetic energy of the fragments being close to zero. The respective above-threshold dissociation spectrum contains an additional, zero-order peak. The laser-induced dissociation from selectively prepared high-lying bound states is shown to be very efficient, with the dissociation probability approaching the maximal value. Flexible tools of state-selective laser control are developed which enable one to achieve selective control of the dissociation spectra resulting in time-selective and space-selective control of the dissociation fragments. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472058
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  • 5
    Electronic Resource
    Electronic Resource
    Immunophenotypic and Functional Characteristics of Haemopoietic Cells from Human Cord Blood (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 42 (1995), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cord blood (CB) as a new source for bone marrow transplantation represents advantageous features concerning stem cell and leucocyte compartments and function. We attempted to get more information about the phenotypes and function of CB cells by investigating their cell surface markers and also the production of IL-2, IFN-γ and IL-6 by mitogen and alloantigen stimulation. The CB cells were characterized by a low proportion of CD3+ T cells, CD4+ T subpopulation, activated T cells and CD3+ CD16/CD56+ cytotoxic cells, suggesting reduced graft versus host potential. The significant increase of CD19/CD3 double positive cells and decrease of CD19/HLA-DR double positive mature B cells reflect that immature B cells exist in CB. In the functional studies, a 27- and 5-fold reduction was observed in the production of IFN-γ by CB cells stimulated with PHA and allogeneic cells, respectively. The production of IL-2 in PHA-stimulated CB cells also showed a 50% determination. Decrease in the production of these cytokines by CB cells is supported by the decline of the proportion of CD3+ T cells. However, an increase was observed in the production of IL-6 by CB cells stimulated with allogeneic cells as compared with the controls. These results suggest a difference in the functional activity of the T helper cell subsets between the CB and peripheral blood and/or differences in the functional maturity of T helper cell subsets and B cells in these compartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1995.tb03685.x
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  • 6
    Electronic Resource
    Electronic Resource
    Biotransformation of [ring-U-14C]atrazine to dealkylated and hydroxylated metabolites in cell-suspension cultures (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 37 (1997), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The biconversion of [14C]atrazine to deaikyt-ated and hydroxylated products was studied in heteroirophic cell-suspension cultures of carrot (Daucus caroia L.), Agrostemma githago L. (corn cockle). Digitalis purpurea L. (purple foxglove), soyabean (Giycine max L. Merr; four different cultivars). Datura stramonium L. (thorn-apple) and wheat (Tritician aestivum L.). During 48 h of incubation, the herbicide was biotransformed by all species; turnovers yields differed considerably and were between 10.1% and 88.0% of applied 14C. Differences were also observed among the soyabean cultivars (10.1-73.5%). Hydroxy-atrazine, de-ethyl-, deisopropyl- and de-ethyt-deisopropylatrazine formed in the cultures were identified by thin-layer chromatography (tlc) (co-chromatography with reference compounds); deaikyiated metabolites were also proved by gas chromatography–mass spectrometry (gc–ms). In addition, highly polar transformation products emerged that were not identified. Portions of non-extractable residues were below 5% (one soyabean cultivar: 8.9%). Atrazine was metabolized by the cells, mainly to its dealkylated derivatives and hydroxyatrazine (totals of 9.4-54, 5%), whereas portions of highly polar products were lower (0.1-26.1%). Exceptions were A. githago (26.0 and 33.6%, respectively) and D, purpurea (4.5 and 25.2% respectively). Thus, plants generally contribute to the environmental degradation of atrazine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3180.1997.d01-71.x
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  • 7
    Electronic Resource
    Electronic Resource
    The severity of clinical symptoms in ragweed-allergic patients is related to the extent of ragweed-induced complement activation in their sera (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 52 (1997), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously reported a correlation between the extent of ragweed allergen (RWA)-induced in vitro serum complement activation and the symptom scores registered daily during the ragweed (RW)-blooming season in RW-allergic patients. The present study was performed in 22 15–17-year-old RW-allergic adolescents. Serum samples were incubated with 100μ/ml RWA, and the generation of different complement activation products was measured by ELISA or RIA. Symptom scores were registered for 4 weeks during the RW-blooming season. The patients were divided according to the extent (low or high) of the generation of complement activation products, and symptom scores registered in the two groups were compared by two-way ANOVA. Significantly higher symptom scores were obtained in the high than in the low complement activation group (P values: 0.049 for C1rC1sC1inh, 0.022 for CSbBbP, 0.015 for C5b-9, 0.0001 for C3a, and 0.0008 for C5a). Similar results were obtained at the measurement performed in the sera obtained from the same patients half a year before the season (P values: 0.022 for C3bBbP, and 0.005 for C5b-9). These findings indicate that complement activation induced by the allergen may enhance the clinical symptoms of RW allergy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.1997.tb00184.x
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  • 8
    Electronic Resource
    Electronic Resource
    Antioxidant micronutrients and gastric cancer (1998)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 12 (1998), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.1998.00006.x
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  • 9
    Electronic Resource
    Electronic Resource
    Effects and side-effects of 2% progesterone cream on the skin of peri- and postmenopausal women: results from a double-blind, vehicle-controlled, randomized study (2005)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 153 (2005), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  For many years topical progesterone has been prescribed by gynaecologists as an antiageing and skin-firming treatment, without any clinical scientific evidence of its effects, tolerability and safety when applied to skin.Objectives  To evaluate the influence of 2% progesterone cream on function and texture of the skin in peri- and postmenopausal women.Methods  A double-blind, randomized, vehicle-controlled study was conducted in 40 subjects. Objective methods for measuring skin elasticity, epidermal hydration and skin surface lipids, clinical monitoring and self-assessment, and determination of blood hormone levels (luteinizing hormone, follicle-stimulating hormone, oestrogen and progesterone) were used to determine effects and side-effects of this treatment at four visits over a 16-week period.Results  The study demonstrated a significant (P ≤ 0·05) increase of the elastic skin properties in the treatment group, as demonstrated by objective measurements of three skin elasticity parameters, whereas in the control group no such effect was observed. This effect in the treatment group was further paralleled by the results of the clinical monitoring, where the 2% progesterone cream yielded consistent superiority over vehicle in counteracting different signs of ageing in the skin of peri- and postmenopausal women. Clinical monitoring showed a greater reduction in wrinkle counts (29·10% vs. 16·50%) and wrinkle depth (9·72% vs. 7·35%) around the right eye, a greater decrease in nasolabial wrinkle depth (9·72% vs. 6·62%) and a significantly higher (P 〈 0·05) increase in skin firmness (23·61% vs. 13·24%) in the treatment group. Epidermal hydration and skin surface lipids did not change significantly in either group during the study. Progesterone was well absorbed in the systemic circulation: mean blood levels rose minimally, but statistically significantly (P = 0·001), by 0·53 ng mL−1. No serious side-effects of the treatment were observed.Conclusions  The results of this study demonstrate that topical 2% progesterone acts primarily in increasing elasticity and firmness in the skin of peri- and postmenopausal women. These effects in combination with good tolerability make progesterone a possible treatment agent for slowing down the ageing process of female skin after onset of the menopause.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.2005.06685.x
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  • 10
    Electronic Resource
    Electronic Resource
    Attosecond spectroscopy in condensed matter (2007)
    [s.l.] : Nature Publishing Group
    Nature 449 (2007), S. 1029-1032 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Comprehensive knowledge of the dynamic behaviour of electrons in condensed-matter systems is pertinent to the development of many modern technologies, such as semiconductor and molecular electronics, optoelectronics, information processing and photovoltaics. Yet it remains challenging to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature06229
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