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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 7700-7707 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new scheme for performing high-resolution kinetic energy measurements on single quantum states of NO is described. Laser excitation of the a 4Π(ν=13–15) and b 4Σ−(ν=3)←X 2Π(ν=0) spin-forbidden bands has been used to produce NO a 4Π, either by direct excitation or after excitation to NO b 4Σ− followed by b→a emission. The sensitivity is compared to previous experiments on CO, employing the forbidden Cameron system. In the course of these experiments, three previously unknown vibronic levels of the a 4Π state were observed for which high precision molecular constants have been obtained. The derived molecular constants have been used to construct a chemically accurate RKR potential for the a 4Π state to within 0.2 eV of the dissociation limit. In addition, the electric dipole moments for the a 4Π(ν=13–14) levels have been determined. By comparing the experimental results with two ab initio calculations, the polarity of the dipole moment of the a 4Π state at equilibrium separation could be determined. A set of supplementary molecular beam laser-induced fluorescence studies on the b 4Σ−(ν=3)←X 2Π(ν=0) band were also carried out. These allowed the fluorescence lifetime of b 4Σ−(ν=3) state to be obtained under collision-free conditions and the electronic origin of the quartet manifold to be determined within 0.03 cm−1. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 50 (1995), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Perennial ryegrass/white clover (Lolium perennel Trifolium repens) pastures of three white clover varieties were compared at UK lowland (Plas Gogerddan, PG) and upland (Bronydd Mawr, BM) sites over three harvest years (1989–91) under continuous variable stocking (ewes and lambs until weaning and lambs thereafter). Mean annual lamb output from small-leaved S 184 (1179 kg ha−1) was 29% greater than that from prostrate small-leaved AberEndura at PG with medium-leaved Huia also giving 19% more output than AberEndura. At BM, output from S 184 (863 kg ha−1) was 19 and 14% greater than that from AberEndura and Huia respectively. The differences in lamb output between the small-leaved varieties owed to a combined effect of higher individual lamb growth rates and greater stock-carrying capacity, both of which were more pronounced in the post-weaning period. The higher output from S 184 relative to Huia at BM was attributed to higher stocking rate, particularly after weaning. Clover productivity and persistence were also studied under three cutting-only managements at PG. Performance under a treatment cut at 2–3 cm every 10 d (T1), which is synonymous with assessment of persistence in UK National List testing, was poor with clover growing point number of only 498 m−2 compared with 4906 m−2 on the grazed sward in autumn 1991. Although productivity and clover content under T3 (cut at 3–4 cm every 42 d — similar to National List yield regime) gave the same varietal ranking as lamb production, there was an under-estimation of the small-leaved varieties, particularly AberEndura, relative to Huia. An intermediate treatment (T2), cut at 3–4 cm every 21 d, also over-estimated the performance of the medium-leaved variety. Herbage data from ground level sampling every 21 d using exclosure cages on the grazed swards were also poorly related to lamb performance. These results highlight the effect of clover variety on lamb production, which appeared to be independent of leaf size, and also confirm the existing problems associated with assessment of white clover varieties using a cutting regime.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2847-2852 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temporal evolution of the radial profile of lithium-like oxygen (OVI or O5+) 3d-4f, 52.0 nm emission from 80 ns rise time, 6–16 kA peak current, pulsed capillary discharges in 1 mm diam, 1 cm long polyacetal capillaries, has been studied. Evidence was seen for a central "flattening'' in this emission. Extreme-ultraviolet, time-integrated, pinhole transmission grating spectra were taken of discharges at 16 and 23 kA peak currents in 0.5 mm diam, 1 cm long capillaries. Spectra obtained at the higher peak current (23 kA) showed evidence of helium-like (CV or C4+) and/or hydrogen-like carbon (CV or C5+) resonance line emission (4.0 and 3.4 nm wavelength) filling the capillary diameter. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3744-3749 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction and testing of a dual-channel photon correlator is reported for the frequency domain imaging of fluorescence lifetimes using photon-counting detection. A light source modulated at radio frequency excites fluorescence, which is detected using an imaging single-photon detector. After discrimination, single-photon events are processed in parallel by the correlation circuit, the purpose of which is to allow both the mean phase delay and the demodulation of fluorescence to be calculated relative to a reference signal derived from the modulated excitation source. Outputs from the correlator are integrated in a computer, resulting in accumulation of images which have been statistically filtered by sine and cosine transforms, and which can be manipulated within the computer to generate a resultant image where contrast depends on fluorescence lifetime rather than fluorescence intensity. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 48-51 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Phase fluorometry and fluorescence lifetime imaging require a source of exciting light which can be modulated at radiofrequency. This is difficult to achieve with reasonable efficiency using conventional light sources with external modulators such as Pockels cells, while laser sources are limited in wavelength tunability. In this paper a low-cost and versatile high-frequency modulated light source is described which is well suited to frequency-domain fluorescence measurements. The source is a modified deuterium arc lamp which can be driven directly at frequencies up to approximately 130 MHz, and which provides a highly stable source of ultraviolet and visible light. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2072
    Keywords: Yohimbine ; Noradrenergic ; Anxiety PTSD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Preclinical and clinical studies have suggested that the acoustic startle reflex (ASR) is a useful model to investigate the neurochemical basis of anxiety and fear states. This work has revealed that the anxiogenic alpha-2 receptor antagonist, yohimbine, increases the amplitude of the ASR in laboratory animals and in healthy human controls. Because of the growing body of data that support the hypothesis that severe stress results in substantial alterations in noradrenergic neuronal reactivity, the present investigation evaluated the effects of yohimbine on the ASR of 18 patients with PTSD and 11 healthy combat controls. Subjects received IV yohimbine (0.4 mg/kg) or saline placebo on 2 separate days in a randomized double blind placebo control design. A trial of two tone frequencies with varied intensity (90, 96, 102, 108, 114 dB) white noise and instantaneous rise time, was delivered binaurally through headphones. Tones were delivered every 25–60 s, for a 40-ms duration. Startle testing was performed 80 min post-infusion and lasted 15–20 min. Yohimbine significantly increased the amplitude, magnitude and probability of the ASR in combat veterans with PTSD, but did not do so in combat controls. Overall startle was significantly larger in the PTSD subjects; however, this did not account for the differential effect of yohimbine, since yohimbine had no significant effect in the control group. This study demonstrates an excitatory effect of yohimbine on the amplitude, magnitude and probability of the ASR in PTSD patients that is not seen in combat controls. In the context of the key role of this reflex in the alarm response, this finding adds to the array of documented behavioral, biochemical and cardiovascular effects of yohimbine in humans which support the relationship between increased noradrenergic function and exaggerated startle symptomatology of PTSD.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Statistics and computing 5 (1995), S. 155-163 
    ISSN: 1573-1375
    Keywords: Interval analysis ; central and non-central F distribution ; self-validating ; extended Horner scheme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A self-validating numerical method based on interval analysis for the computation of central and non-central F probabilities and percentiles is reported. The major advantage of this approach is that there are guaranteed error bounds associated with the computed values (or intervals), i.e. the computed values satisfy the user-specified accuracy requirements. The methodology reported in this paper can be adapted to approximate the probabilities and percentiles for other commonly used distribution functions.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5060
    Keywords: barley landraces ; drought ; Hordeum vulgare ; leaf colour ; photosynthesis ; photosystem I and II ; thylakoid chlorophyll-proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Barley breeders at ICARDA have observed that genotypes adapted to dry regions have leaves which are lighter in colour than those of unadapted ones. We measured photosynthesis, chlorophyll content and chlorophyll a:b ratios in two sets of genotypes which had previously been observed to have either light green or dark green leaves when grown in the field. Thylakoid membranes were also extracted and the proteins analysed on SDS-PAGE gels. The light leaf colour was associated with a higher chlorophyll a:b ratio. This was a measure of a reduction in the amount of antenna chlorophyll compared to that in the core complex of PSII. Genotypes with light green leaves had consistently less chlorophyll per unit leaf area and lower photosynthetic rates per unit area than those with dark green leaves. It is suggested that these features of light green leaves may confer the ability to adapt to high levels of irradiance under drought conditions. This ability may result from a high rate of photosynthetic electron transport through each PSII reaction centre, thus reducing the risk of damage from the overexcitation of these centres.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 58 (1995), S. 393-402 
    ISSN: 0730-2312
    Keywords: adipocytes ; bone morphogenetic proteins ; differentiation ; bone marrow stromal cells ; transforming growth factor β ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The bone morphogenetic proteins were originally identified based on their ability to induce ectopic bone formation in vivo and have since been identified as members of the transforming growth factor-β gene superfamily. It has been well established that the bone morphogenetic cytokines enhance osteogenic activity in bone marrow stromal cells in vitro. Recent reports have described how bone morphogenetic proteins inhibited myogenic differentiation of bone marrow stromal cells in vitro. In vivo, bone marrow stromal cells differentiate along the related adipogenic pathway with advancing age. The current work reports the inhibitory effects of the bone morphorphogenetic proteins on adipogenesis in a multipotent murine bone marrow stromal cell line, BMS2. When exposed to bone morphogenetic protein-2, the pre-adipocyte BMS2 cells exhibited the expected induction of the osteogenic-related enzyme, alkaline phosphatase. Following induction of the BMS2 cells with adipogenic agonists, adipocyte differentiation was assessed by morphologic, enzymatic, and mRNA markers. Flow cytometric analysis combined with staining by the lipophilic fluorescent dye, Nile red, was used to quantitate the extent of lipid accumulation within the BMS2 cells. By this morphologic criteria, the bone morphogenetic proteins inhibited adipogenesis at concentrations of 50 to 500 ng/ml. This correlated with decreased levels of adipocyte specific enzymes and mRNAs. The BMS2 pre-adipocytes constitutively expressed mRNA encoding bone morphogenetic protein-4 and this was inhibited by adipogenic agonists. Together, these findings demonstrate that bone morphogenetic proteins act as adipogenic antagonists. This supports the hypothesis that adipogenesis and osteogenesis in the bone marrow microenvironment are reciprocally regulated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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