Search Results - (Author, Cooperation:F. Wittmann)
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1Latest Papers from Table of Contents or Articles in PressH. ter Steege ; N. C. Pitman ; D. Sabatier ; C. Baraloto ; R. P. Salomao ; J. E. Guevara ; O. L. Phillips ; C. V. Castilho ; W. E. Magnusson ; J. F. Molino ; A. Monteagudo ; P. Nunez Vargas ; J. C. Montero ; T. R. Feldpausch ; E. N. Coronado ; T. J. Killeen ; B. Mostacedo ; R. Vasquez ; R. L. Assis ; J. Terborgh ; F. Wittmann ; A. Andrade ; W. F. Laurance ; S. G. Laurance ; B. S. Marimon ; B. H. Marimon, Jr. ; I. C. Guimaraes Vieira ; I. L. Amaral ; R. Brienen ; H. Castellanos ; D. Cardenas Lopez ; J. F. Duivenvoorden ; H. F. Mogollon ; F. D. Matos ; N. Davila ; R. Garcia-Villacorta ; P. R. Stevenson Diaz ; F. Costa ; T. Emilio ; C. Levis ; J. Schietti ; P. Souza ; A. Alonso ; F. Dallmeier ; A. J. Montoya ; M. T. Fernandez Piedade ; A. Araujo-Murakami ; L. Arroyo ; R. Gribel ; P. V. Fine ; C. A. Peres ; M. Toledo ; C. G. Aymard ; T. R. Baker ; C. Ceron ; J. Engel ; T. W. Henkel ; P. Maas ; P. Petronelli ; J. Stropp ; C. E. Zartman ; D. Daly ; D. Neill ; M. Silveira ; M. R. Paredes ; J. Chave ; A. Lima Filho Dde ; P. M. Jorgensen ; A. Fuentes ; J. Schongart ; F. Cornejo Valverde ; A. Di Fiore ; E. M. Jimenez ; M. C. Penuela Mora ; J. F. Phillips ; G. Rivas ; T. R. van Andel ; P. von Hildebrand ; B. Hoffman ; E. L. Zent ; Y. Malhi ; A. Prieto ; A. Rudas ; A. R. Ruschell ; N. Silva ; V. Vos ; S. Zent ; A. A. Oliveira ; A. C. Schutz ; T. Gonzales ; M. Trindade Nascimento ; H. Ramirez-Angulo ; R. Sierra ; M. Tirado ; M. N. Umana Medina ; G. van der Heijden ; C. I. Vela ; E. Vilanova Torre ; C. Vriesendorp ; O. Wang ; K. R. Young ; C. Baider ; H. Balslev ; C. Ferreira ; I. Mesones ; A. Torres-Lezama ; L. E. Urrego Giraldo ; R. Zagt ; M. N. Alexiades ; L. Hernandez ; I. Huamantupa-Chuquimaco ; W. Milliken ; W. Palacios Cuenca ; D. Pauletto ; E. Valderrama Sandoval ; L. Valenzuela Gamarra ; K. G. Dexter ; K. Feeley ; G. Lopez-Gonzalez ; M. R. Silman
American Association for the Advancement of Science (AAAS)
Published 2013Staff ViewPublication Date: 2013-10-19Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: *Biodiversity ; Models, Biological ; Population ; *Rivers ; South America ; Trees/*classification/*physiologyPublished by: -
2Latest Papers from Table of Contents or Articles in PressM. C. Bott, J. M. Brader, R. Wittmann, F. Winterhalter, M. Marechal, and A. Sharma
American Physical Society (APS)
Published 2018Staff ViewPublication Date: 2018-07-10Publisher: American Physical Society (APS)Print ISSN: 1539-3755Electronic ISSN: 1550-2376Topics: PhysicsKeywords: Colloids, Complex Fluids, and Active MatterPublished by: -
3Articles: DFG German National LicensesBernhard-Höfer, K. ; Zrenner, A. ; Brunner, J. ; Abstreiter, G. ; Wittmann, F. ; Eisele, I.
Woodbury, NY : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Pseudomorphic Si1−xGex/Si multi-quantum well structures for waveguide applications have been grown on (110) Si by molecular beam epitaxy. In a series of samples the Ge fraction x has been varied from x=0.25 to x=0.37 and x=0.50, respectively. We have used photocurrent spectroscopy on mesa diodes to demonstrate that the absorption edge of the strained Si1−xGex quantum wells can be tuned from 1.3 to 1.55 μm by the Ge fraction x. Realization and characterization of single-mode (110) Si1−xGex rib waveguides with end facets of high optical quality, prepared by cleaving, is reported. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesZotov, A. V. ; Wittmann, F. ; Lechner, J. ; Eisele, I. ; Ryzhkov, S. V. ; Lifshits, V. G.
Woodbury, NY : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: A set of the different Si:Al and Si:B surface phases capped by amorphous Si layers were grown by molecular beam epitaxy (MBE). The formation of the buried interfaces was studied by low-energy electron diffraction and Auger electron spectroscopy. The conductivity and Hall effect measurements of the grown samples revealed that only the buried Si(111)(square root of)3×(square root of)3−B surface phase manifests itself as a highly doped degenerated layer, while all the buried Si:Al surface phases covered by amorphous Si show negligible activation of dopants. The difference in electrical properties of the buried surface phases are discussed in terms of the characteristics of their atomic structure. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesWITTMANN, P. H. ; WITTMANN, F. W. ; CONNOR, J. ; CONNOR, T.
Oxford, UK : Blackwell Publishing Ltd
Published 1994Staff ViewISSN: 1365-2044Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineNotes: A new design of keyed filler with a dead space of 1.1 ml was used with 50 bottles of isoflurane to fill vaporizers. The volume of isoflurane remaining in the‘empty’bottle, the residual volume, was measured. The trial was repeated using the old style filler which has a dead space of 3.3 ml. The new filler reduced the mean residual volume by 73% but still did not completely empty the bottle.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 0375-9601Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesHammerl, E. ; Wittmann, F. ; Eisele, I. ; Heinzel, T. ; Kuhn, S. ; Lorenz, H. ; Kotthaus, J.P.
Amsterdam : ElsevierStaff ViewISSN: 0022-0248Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: Chemistry and PharmacologyGeosciencesPhysicsType of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesStaff View
ISSN: 0039-6028Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesLewis, J. ; Khan, M.S. ; Kakkar, A.K. ; Johnson, B.F.G. ; Marder, T.B. ; Fyfe, H.B. ; Wittmann, F. ; Friend, R.H. ; Dray, A.E.
Amsterdam : ElsevierStaff ViewISSN: 0022-328XSource: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: Chemistry and PharmacologyType of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesKhan, M.S. ; Kakkar, A.K. ; Ingham, S.L. ; Raithby, P.R. ; Lewis, J. ; Spencer, B. ; Wittmann, F. ; Friend, R.H.
Amsterdam : ElsevierStaff ViewISSN: 0022-328XKeywords: Acetylene ; Electronic structure ; Molecular orbital calculations ; Phosphine ; Polymer ; RutheniumSource: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: Chemistry and PharmacologyType of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesStaff View
ISSN: 0031-9163Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesStaff View
ISSN: 0038-1098Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesStaff View
ISSN: 0038-1098Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesStaff View
ISSN: 0375-9601Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesStaff View
ISSN: 0370-2693Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PhysicsType of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesStaff View
ISSN: 1434-601XSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The theory of Dzyaloshinskii allows us to calculate the van der Waals force acting between two surfaces which are held at a distance of 104 Å and less. This calculation was based on the experimentally determined absorption data of quarz. The deflection of a thin quarz plate which was supported at one end with a vaporized bar has been measured to verify the theoretical results. Within the range of accuracy a fair agreement could be reached.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesStaff View
ISSN: 1359-5997Source: Springer Online Journal Archives 1860-2000Topics: Architecture, Civil Engineering, SurveyingDescription / Table of Contents: Summary Some properties of adsorbed water in hardened cement paste and in the three completely hydrated main constituents of portland cement have been examined by means of differential thermoanalysis, thermo-gravimetry and nuclear magnetic resonance. When a dried specimen is re-wetted, the adsorbed water first contributes to the build-up of a mono-layer. Only in the higher humidity range is the sorbed water partly bound as inter-layer hydrate water and as hydrate water. According to the first results of the nuclear magnetic resonance measurements the water adsorbed in the monolayer behaves like a two-dimensiional Van-der-Waals-gas.Notes: Résumé Quelques propriétés de l'eau adsorbée dans la pâte de ciment durcie et dans les trois constituants principaux complètement hydratés du ciment Portland ont été étudiées avec l'analyse thermique différentielle, la thermo-gravimétrie et la résonance magnétique nucléaire. Lorsqu'une éprouvette séchée est réhumidifiée, l'eau adsorbée contribe d'abord à la formation d'une mono-couche. L'eau adsorbée, en tant qu'eau d'hydratation, n'est partiellement liée dans la structure du sel que pour les humidités les plus élevées. Selon les tout premiers résultats fournis par les mesures de la résonance magnétique nucléaire, l'eau adsorbée dans la mono-couche se comporte comme un gaz bi-dimensionnel de Van-der-Waals.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesStaff View
ISSN: 1359-5997Source: Springer Online Journal Archives 1860-2000Topics: Architecture, Civil Engineering, SurveyingDescription / Table of Contents: Summary Until now there exist controversial views on restoration and in particular on consolidation of aged natural stone. One reason for this is the lack of reliable test methods. In this report first of all some results obtained by conventional methods are described. The influence of a treatment with silicic ester on flexural strength, porosity and surface hardness has been studied. Then a new method is proposed. With this method the biaxial flexural strength of circular discs is measured. The experimental set-up, the theoretical basis as well as the evaluation of experimental results are outlined. This new method is first tested with some preliminary experiments on unaged natural stone. Potential applications in practice are outlined by means of an experimental determination of the consolidating effect of a silicic ester on an aged sand stone. It is shown that it is possible to determine the strength profile in cutting circular discs from drilled cores. In testing identical discs taken from a core of a treated stone the consolidating effect is obtained quantitatively and as function of the distance from the surface. By using these results it is possible to optimize a consolidating treatment. Finally tests on compacts are described. Usually the variability of properties of natural stone is considerable. Therefore we prepared compacts with varying porosities. Measurements on compacts are especially suitable for comparative tests of different consolidating agents and of the durability of the consolidating treatment. The time-dependence of the strength development and the durability of a consolidating treatment can be followed in a non-destructive way by measuring the modulus of elasticity.Notes: Résumé Faute de méthodes de mesures fiables, il existe encore de nos jours une certaine insécurité lors de la restauration de monuments en pierre naturelle. Ce rapport décrit en premier lieu des résultats concernant quelques méthodes conventionnelles pour la détermination expérimentale de l'efficacité de consolidation au moyen d'esters siliciques, en particulier la résistance à la flexion, la porosité et la dureté superficielle. En second lieu, on propose une nouvelle méthode par laquelle on détermine la résistance à la flexion bi-axiale sur des disques de pierre naturelle. Le montage de l'essai et l'interprétation seront brièvement décrits. La méthode en question est tout d'abord testée sur la pierre naturelle non altérée. Les possibilités d'utilisation dans la pratique de mesures d'assainissement sont indiquées pour un grès altéré. La méthode a permis de mesurer en premier lieu la chute de résistance. D'une manière analogue on peut obtenir le résultat d'une consolidation. On peut ainsi optimaliser un assainissement de la pierre. Pour terminer, on a décrit des mesures faites sur des comprimés obtenus à partir de pierre concassée (Compacts). Ces essais sont particulièrement destinés à l'étude systématique de mesures comparatives.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesStaff View
ISSN: 1359-5997Source: Springer Online Journal Archives 1860-2000Topics: Architecture, Civil Engineering, SurveyingType of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesStaff View
ISSN: 1359-5997Source: Springer Online Journal Archives 1860-2000Topics: Architecture, Civil Engineering, SurveyingDescription / Table of Contents: Summary The functional relation between creep deformation and stress relaxation can be represented by the Volterra integral equation. By substituting the creep function and the relaxation function into this equation and comparing coefficients it is possible to obtain an expression which relates the ultimate creep to the relaxed stress at time t=∞. The rate at which the stress decreases at the begenning of the experiment is proportional to the creep velocity, and the constant of proportionality is the modulus of elasticity. It is shown the half-life time of the relaxation process is always smaller than the corresponding half-life time of the creep process. The derived equations are compared with experimental results described in the literature.Notes: Résumé On peut traduire la relation entre fluage et relaxation par l'équation intégrale de Volterra. La substitution des fonctions «fluage» et «relaxation» dans cette équation et la comparaison des coefficients permet d'obtenir une expression qui relie le fluage final et la contrainte relâchée au tempst=∞. Le taux de décroissance au début de l'expérience est proportionnel à la vitesse de fluage; la constante de proportionnalité est le module d'élasticité. On montre que la mi-temps du processus de relaxation est toujours plus petite que la mi-temps correspondance du processus de fluage. On compare les équations dérivées avec les résultats expérimentaux décrits dans la littérature.Type of Medium: Electronic ResourceURL:
