Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1942-1946 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A detailed description of an experimental configuration based on photothermal deflection spectroscopy (PDS) and transmittance techniques that enables high sensitivity room temperature absorption measurements over a spectral region extending between 300 nm and 3.4 μm is reported. It is shown that the simultaneously determined PDS and transmittance spectra can be processed to eliminate completely the interference induced oscillations in the spectra which are observed when the film refractive index differs substantially from the one of the substrate. A configuration based on the photopyroelectric and transmittance techniques, though less sensitive than the previous one, is shown to be suitable for the same kind of measurements at cryogenic temperatures. Absorption bands in implanted Si between 2.8 and 3.4 μm have thus been detected and tentatively associated with multiphonon defect assisted absorption bands. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2839-2841 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Textured diamond films have been deposited on single-crystal silicon substrates by microwave plasma-enhanced chemical vapor deposition. Several unconventional gas mixtures (CO2–CH4, CO2–C2H6, and CO2–C2H4) were used in order to study the texturing formation within the diamond stability region in the C–O–H phase diagram. Optical emission spectroscopy was used to monitor the compositional dependence of the plasma emission. The obtained diamond films were characterized by scanning electron microscopy and x-ray diffraction. Diamond films deposited with all the gas mixtures showed very similar surface morphologies and (100) texturing was achieved only within a very narrow compositional range. Finally, a correlation was found between texturing conditions and CH and C2 line intensities in the plasma emission spectra. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 879-881 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the emission spectra from plasmas excited in several compositions of three different gas mixtures useful for the growth of diamond films, namely CH4-H2 (the classical one), CH4-CO2 and C2H2-CO2 (not previously reported by other authors). In all three cases we find the same correlation between the quality of the obtained diamond films and some spectral features: in particular, the yield of the best diamond films corresponds to the presence of the emission line at wavelength 431 nm ascribed to CH, in the absence of the emission band at 505–517 nm attributed to C2. The appearance and the progressive increase of the latter corresponds to a gradual worsening of the diamond film quality. We propose such spectral features of the plasma as a general and practical gauge of the diamond film growth conditions, for any gas mixture used.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2663-2665 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A front detection photopyroelectric configuration has been used to study the nonlinear heat transport processes that take place in the vicinity of the smectic A–nematic phase transition of the 9 CB liquid crystal. An increase in the sensitivity of this technique with respect to other photothermal techniques as far as the phase transition detection is concerned has been obtained. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 553-555 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the time-resolved reflectivity changes in the picosecond–nanosecond range induced by picosecond visible optical pulses in ion-implanted amorphous silicon-on-sapphire. Illumination from the front side of the thin film probes the picosecond carrier relaxation processes. Heat release from trapped carriers in the 100-ps range is shown to be significant. Illumination from the substrate side probes, in addition, the ultrafast diffusion of heat to the substrate. The derived thermal diffusivity is shown to correspond to a near-surface layer much thinner than the optical absorption depth. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2359-2361 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial Bi2Sr2CaCu2O8+x films have been grown by the liquid phase technique on twinned LaGaO3 and untwinned SrTiO3 substrates. Crystallographic properties and transition temperatures are comparable, but the transport critical current density Jc depends dramatically on the substrate. Films grown on SrTiO3 have Jc comparable with single crystals, while films grown on LaGaO3 have Jc values extrapolated at 4.2 K in the 104–105 A cm−2 range. This effect is demonstrated to be a consequence of the presence of twinning domains in the substrate.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Natural killer (NK) cells represent the first line of defence against viral infections but, in the case of hepatitis B virus (HBV), may also be involved in liver injury. We here compared NK-cell activity of 11 patients with acute HBV infection, either HIV-positive or HIV-negative, with that of 11 healthy subjects. One of the HIV-positive patients, characterized by a severe immunodeficiency, died 3 weeks after hospitalization for HBV-related fulminant hepatitis (FH). He displayed a remarkable NK-cell cytotoxicity against both cell lines and autologous dendritic cells, whereas the NK-cell activity of the remaining patients was significantly reduced as compared with healthy individuals. Our findings suggest that NK-cell-mediated cytotoxicity could contribute to the development of HBV-related acute liver failure in HIV-positive patients with severe immunodeficiency. An immunopathological model of FH in immunocompromised patients was proposed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Narp is an immediate early gene product that acts extracellularly to cluster AMPA receptors at excitatory synapses. The present study tested the hypothesis that drugs of abuse alter Narp expression and thereby influence AMPA receptor transmission in addiction-related circuits. Immunohistochemical studies demonstrated the existence of Narp-positive cells in hippocampus, prefrontal cortex (PFC) and nucleus accumbens (NAc), with lower levels of staining in the ventral tegmental area (VTA). To study the effects of psychomotor stimulants, Narp levels were quantified by Western blotting and normalized to actin. There were no differences in Narp levels in any brain region between rats treated with repeated saline injections, a single amphetamine injection (5 mg/kg), repeated amphetamine injections (5 mg/kg × 5 days), or repeated cocaine injections (20 mg/kg twice daily × 7 days). We also examined the possible role of Narp in individual differences in responding to a novel environment, a predictor of behavioural responses to psychomotor stimulant drugs including the propensity to acquire drug self-administration. Narp levels in the PFC, but not other regions, were significantly correlated with locomotor activity in a novel environment. These findings suggest that differential Narp expression in the PFC may be involved in determining individual vulnerability to drugs of abuse, perhaps by influencing the activity of its excitatory projections.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Ageing is accompanied by a decline in neurogenesis and in polysialylated isoforms of neural cell adhesion molecule (PSA-NCAM) expression within the hippocampus and by elevated basal levels of circulating corticosterone. In a companion study, we demonstrated that suppression of corticosterone by adrenalectomy increased neurogenesis and PSA-NCAM expression in the dentate gyrus of adult rats. Here we show that adrenalectomy increased neurogenesis in this structure in old rats, as measured by the incorporation of 5-bromo-2′-deoxyuridine in neuronal progenitors. This effect was prevented by corticosterone replacement. In contrast, PSA-NCAM expression remained unchanged in comparison with controls. Thus, in the aged brain, stem cells are still present and able to enter the cell cycle. This may point to ways of protecting or treating age-related cognitive impairments.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 20
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The gyrus dentatus is one of the few areas of the brain that continues to produce neurons after birth. The newborn cells differentiate into granule cells which project axons to their postsynaptic targets. This step is accompanied by the transient expression of the polysialylated isoforms of neuronal cell adhesion molecules (PSA-NCAM) by the developing neurons. Glucocorticoid hormones have been shown to inhibit neurogenesis. We noted a functional correlation between PSA-NCAM expression and glucocorticoid action after manipulation of corticosterone levels in the adrenalectomized rat. Adrenalectomy increased neurogenesis, evaluated from the incorporation of 5-bromo-2′-deoxyuridine in neuronal precursors, as well as PSA-NCAM expression. The increase in PSA-NCAM-immunoreactive (IR) cells in the gyrus dentatus, evidenced 72 h following adrenalectomy, persisted for at least a month. It was accompanied by enhanced dendritic arborization of PSA-NCAM-IR cells in the gyrus dentatus and by an increase in number of PSA-NCAM-IR fibres in the CA3 subfield. Neurogenesis was normalized by restitution of diurnal or nocturnal levels of corticosterone, whereas normalization of PSA-NCAM expression was only observed after simulation of the complete circadian fluctuation of the hormone. Our findings reveal the complex action of corticosterone in modulating the expression of PSA-NCAM in the gyrus dentatus of the hippocampal formation. They also highlight the importance of corticosterone fluctuations in the control of neurogenesis and plasticity in this structure.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...