Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Picosecond time evolution of photoexcited hot-electron mobility in GaAs and the speed of photoresponse (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3189-3196 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transient mobility of hot electrons photoexcited in undoped GaAs by subpicosecond laser pulses is calculated. For this, we solve the time-dependent Boltzmann transport equation in the presence of a low-frequency, weak electric field. The attention is focused mainly on the role of intracentral Γ valley scattering in determining the delay in the mobility rise on the picosecond time scale, and the hot-electron energies are assumed to be below the thresholds for possible side-valley transfers (Γ→L,X). We consider the mobility response under two separate conditions of excited carrier density, namely, (1) low-density excitations for which the electron–longitudinal phonon (LO) Fröhlich interaction initially dominates in the carrier relaxation and (2) high-density excitations for which the electron-electron interaction is faster than all other collisions. The mobility of hot electrons is very small (〈1000 cm2/V s) just after photogeneration. It rises to its maximum value with a time constant decided by the various scattering processes which are influenced by the values of the carrier density and the lattice temperature. We find that the mobility rise can be quite slow up to the scale of several picoseconds, even when the possible delay due to side-valley scattering is absent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342670
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Transient electrical conductivity of nonequilibrium carriers excited by subpicosecond optical pulses in GaAs (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 323-325 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We calculate the time-dependent electrical conductivity σ(t) for the nonequilibrium carriers excited by a subpicosecond laser pulse in a polar semiconductor like GaAs. The photoexcited carriers are assumed to relax towards equilibrium by emitting longitudinal optical (LO) phonons in a cascade via the strong Fröhlich interaction. We show that σ(t), obtained in the picosecond time domain, has a highly nonlinear time evolution. It develops a pronounced dip, with its value becoming negative, whenever the generated low density carrier distribution is sharply peaked initially at energy ε(approximately-equal-to)m(h-dash-bar)ωLO, m=integer, (h-dash-bar)ωLO being the long wavelength LO phonon energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98990
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Post-transcriptional enhancement of Escherichia coli bgl operon silencing by limitation of BglG-mediated antitermination at low transcription rates (2002)
    Oxford, UK : Blackwell Science Ltd.
    Molecular microbiology 43 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The silent bgl operon of Escherichia coli is activated by spontaneous mutations that derepress its promoter. In addition, expression depends on specific transcriptional antitermination within the operon by the antiterminator protein BglG. Here, we show that BglG-mediated antitermination limits expression of the bgl operon when the cellular transcription rate is low. The expression levels of chromosomally encoded activated bgl operon alleles are low but increase significantly when BglG protein is provided in trans or when the expression is rendered inde-pendent of BglG-mediated antitermination by mutation of the terminator. Plasmid-encoded activated bgl operon alleles are expressed at high levels. Moreover, a moderate (threefold) further increase in the transcription rate of chromosomally encoded activated bgl operon alleles in an rpoS mutant can result in high (up to 50-fold increased) expression levels. These data show that the expression of the bgl operon does not correlate linearly with its cellular transcription rate. Moderate differences in the transcription initiation rate are amplified post-transcriptionally into large changes in the expression level of the operon by the requirement of a threshold for BglG-mediated antitermination. Implications for bgl operon regulation by global regulators H-NS, RpoS and others are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02734.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    From local identity to global integrity (2002)
    Bingley : Emerald
    Leadership & organization development journal 23 (2002), S. 174-185 
    Details
    ISSN: 0143-7739
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Economics
    Notes: Organizations have never addressed what it means to be global in its depth and entirety. It has been equated with being international, or having offices in different countries. It has been approached and appropriated through historical lenses of modernization, and of what sociologist Martin Albrow calls the "rational project". It is felt that we have come to a situation that is nothing short of a crisis. Explores the depths of "global integrity" with a view to providing individuals, organizations and societies with the tools to engage in becoming global. In the process introduces our concept of the "four worlds," and argues that each needs to be progressively transformed, from a local identity towards global integrity, if our current crisis is to be in any sense resolved. Such a resolution, moreover, requires, in each cultural case, tapping the core and bedrock as well as the subsoil and topsoil of each, as it were, with a view to evolving from a formative (local), as opposed to de-formative, towards a normative, re-formative and ultimately transformative (global) perspective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/01437730210429043
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The histone-like nucleoid structuring protein H-NS represses the Escherichia coli bgl operon downstream of the promoter (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 52 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Specificity of repression by the histone-like nucleoid structuring protein and pleiotropic regulator, H-NS, is exceptionally high in case of the Escherichia coli bgl (β-glucoside) operon. Here we present evidence that H-NS represses the operon at two levels. The binding of H-NS to an upstream silencer results in an ∼threefold repression of the catabolite gene regulator protein (CRP) dependent bgl promoter. In addition, H-NS binds to a silencer region located approximately 600–700 base pairs downstream of the promoter, within the coding region of first gene, bglG, resulting in a ∼sevenfold further decrease of expression. Repression by H-NS at the downstream silencer requires termination factor Rho and is reduced by translation of the bglG mRNA, but is independent of the promoter. This suggests that H-NS induces polarity of transcription by acting as a roadblock to the elongat-ing RNA polymerase. The control of the bgl operon by H-NS at two levels results in a highly specific repression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04001.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Multimouth surfaces for synthetic actor animation (1994)
    Springer
    The visual computer 10 (1994), S. 388-406 
    Details
    ISSN: 1432-2315
    Keywords: Human animation ; Body shape ; Parametric surfaces ; Continuity ; NURBS ; S-patches
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Most parts of the human body are cylindrical in shape. Generalized cylinders, with two cross-sectional openings, are a logical choice to represent these cylindrical shapes. However, a variety of human body regions can be visualized as surfaces with multiple openings or multimouth (MM) surfaces. Some examples of such surfaces are the pelvis, the chest, and the palms of the hands. We investigated the suitability of non-uniform rational B-spline (NURBS) formulation for creating multimouth surfaces. Two techniques, the surface wrapping model and the garland model, are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01900664
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Impairment of dendritic cells and adaptive immunity by anthrax lethal toxin (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 329-334 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Anthrax poses a clear and present danger as an agent of biological terrorism. Infection with Bacillus anthracis, the causative agent of anthrax, if untreated can result in rampant bacteraemia, multisystem dysfunction and death. Anthrax lethal toxin (LT) is a critical virulence factor of B. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01794
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Single cell protein production by photosynthetic bacteria grown on the clarified effluents of biogas plant (1984)
    Springer
    Applied microbiology and biotechnology 19 (1984), S. 199-202 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Anaerobically digested cow dung was separated by centrifugation into solid residue and liquid supernatant fractions. Clarified supernatant fraction, rich in volatile fatty acids, supported the growth of photosynthetic bacteria. Single cell protein from different photosynthetic bacteria, grown on clarified supernatant, was found to be rich in essential and sulphur amino acids. Rhodopseudomonas capsulata produced the best single cell protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256454
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    One dimensional flow of a plasma with an external magnetic field (1965)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 16 (1965), S. 537-538 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Zusammenfassung Eine Lösung der Gleichungen der eindimensionalen Plasmaströmung in Anwesenheit eines externen magnetischen Feldes senkrecht zur Strömungsrischtung wird entwickelt im speziellen Fall: (i)P r =3/4, (ii)c p -constant und (iii)T=T(u).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01593933
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Sunspots and physics of magnetic flux tubes overstability and Kelvin-Helmholtz instability in a magnetic field (1983)
    Springer
    Astrophysics and space science 89 (1983), S. 201-220 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the dynamical properties of convective overstability and Kelvin-Helmholtz instability in a vertical magnetic field with a downdraft. The Kelvin-Helmholtz instability and overstability produce the upward downward propagating Alfvén waves depending upon the magnitudes of the kinematic viscosity coefficient (eddy viscosity) ν, and thermometric conductivity κ. It is found that the instability may be driven by the density stratification and the effect of the eddy viscosity is to make the system stable. We discuss also the interaction of the overstability inx〈0 and the downdraft inx〉0, and the overstability at a vertical boundary of the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01008397
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...