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Retrospective analysis of GnRH analogue administration in patients with advanced ovarian cancer
(1992)
Studies of the evolution of the optical properties of metal clusters as a function of size have gained considerable attention in the last few years. One theoretical approach starts from large metal clusters, which can be described by classical electrodynamics, provided the dielectric functions of the clusters are known. the resulting resonant features in the absorption spectra are commonly called surface plasmons and are collective excitations of the electron system.The present paper discusses the electrodynamic (Mie) theory for large clusters of different metals, also considering the range of validity of this approach towards smaller cluster sizes. More details can be found in an extended review on this topic which is to be published soon [1].
Untersuchungen zur Amenorrhoe unter adjuvanter CMF-Chemotherapie bei Mammakarzinom-Patientinnen
(1993)
Width of cluster plasmon resonances: Bulk dielectric functions and chemical interface damping
(1993)
The damping of collective electron resonances in clusters which develop into plasmon polaritons at larger sizes is investigated for free, supported, and embedded neutral metal clusters. Embedding of free 2 nm Ag clusters of 2-nm diameter into a SiO2 matrix leads to an increase of the width of the resonances by more than a factor of 3. The optical spectra are compared with the Mie theory using size-effect-modified dielectric functions of the solid state. The results corroborate the assumption that the widths of the resonances strongly depend on chemical interface effects. The results are briefly discussed with regard to limited-mean-free-path and quantum-size-effect theories and a recent approach by Persson. It is demonstrated that the widths of the spectra of supported and embedded clusters have to be interpreted with care since true intrinsic size effects of the clusters appear to be less effective than previously believed and can be obscured by the chemical interface damping.
© 1993 The American Physical Society
Laser-induced desorption of metal atoms from the surface of small metal particles has been investigated as a function of the shape of the particles and the polarization of the incident laser light. The particles were supported on LiF, quartz or sapphire substrates. In a first set of experiments, the shape of the particles was determined by recording optical transmission spectra with s- and p-polarized light incident under an angle of typically 40° with respect to the surface normal. The metal particles turn out to be oblate, the ratio of the axes perpendicular and parallel to the substrate surface being on the order of 0.5. This ratio decreases with increasing particle size. Also, the particles change shape if the temperature is raised. In further experiments, s- and p-polarized light has been used to stimulate desorption of atoms via surface plasmon excitation. It is found that the desorption rate markedly depends on the polarization of the light. This is explained by excitation of the collective electron oscillation along different axes of the non-spherical particles.
Results on laser-induced desorption of metal atoms from small metal particles are presented. Experiments have been performed on sodium, potassium, and silver particles supported on a LiF(100) single-crystal surface under ultrahigh vacuum conditions. Measurements include the determination of the desorption rate as a function of laser wavelength, laser intensity, average particle size, and substrate temperature, the determination of the kinetic energy of the desorbed atoms, the investigation of the optical spectra of the supported metal particles, and the study of the influence of adsorbate molecules on the desorption rate. Furthermore, theoretical extinction and absorption spectra of the metal particles have been calculated with the classical electrodynamical Mie theory as a function of average particle size and excitation wavelength. Also, the radial electric field at the particle surface was computed. The results of the experiments and theoretical calculations are combined to give a consistent picture of the mechanism of metal-atom desorption by electronic excitation with laser light. A realistic surface potential from which the atoms escape and nonlocal optical effects are taken into account. The latter introduce additional absorption channels by the formation of electron-hole pairs in the surface layer of the particle which relax into antibonding states before desorption occurs. Finally, the mechanism is discussed in the light of similar phenomena observed for thin metal films. Possibilities for future work are outlined.
© 1993 The American Physical Society
Beleuchtet man die Oberfläche eines Festkörpers mit Laserlicht, können darauf adsorbierte Atome oder Moleküle abgelöst werden. Solche Desorptionsprozesse sind in jüngster Zeit in zahlreichen Experimenten untersucht worden, wobei sich das Interesse sowohl auf die Erforschung der zugrundeliegenden Mechanismen als auch auf mögliche Anwendungen dieser Reaktionen, zum Beispiel zur gezielten Modifizierung von Oberflächen, konzentriert. Besonders interessant ist das laserinduzierte Aufbrechen von Bindungen zur Oberfläche dann, wenn es nicht einfach als thermischer Prozeß durch eine Temperaturerhöhung hervorgerufen wird, sondern direkt auf einer elektronischen Anregung beruht. Solche nichtthermischen Prozesse werden selbst für Metalle beobachtet, obwohl die Kopplung der elektronischen Anregung an das Substrat hier besonders schnell abläuft. Der zugrundeliegende Mechanismus beruht auf dem Zusammenspiel einer kollektiven Elektronenoszillation und einer lokalisierten Einzelelektronenanregung, wobei auch nichtlokale optische Effekte in der Metalloberfläche eine wichtige Rolle spielen.
The results of an experimental study of the optical and photoelectrical properties of Eu-containing lead chalcogenides and superlattices are presented. From both sets of experiments band offset data for the lead chalcogenide-europium chalcogenide heterojunction are derived. The results are compared with the data obtained from a linear interpolation of the band structures between those of the binaries.
On the theory of composite gauge bosons: Calculation of coupling constants and covariant derivatives
(1993)
An innovative net-based methodology to integrate qualitative and quantitative analysis of distributed software systems is outlined, and an on-going prototype implementation of a related graphic-oriented tool kit is sketched. The proposed method combines qualitative analysis, monitoring and testing as well as quantitative analysis on the basis of a net-based intermediate representation of the distributed software system under consideration. All transformations (from the distributed software system into a first Petri net model, and between the different kinds of net models) can be made formally, and therefore automated to a high degree. The evaluation of quantitative properties is based on so-called object nets which are obtained by a property-preserving structural compression and quantitative expansion of the qualitative model. In this way, the frequency and delay attributes necessary to generate quantitative models are provided by the monitoring and testing component.
An innovative net-based methodology to integrate qualitative and quantitative analysis of distributed software systems is outlined, and an on-going prototype implementation of a related graphic-oriented tool kit is sketched. The proposed method combines qualitative analysis, monitoring and testing as well as quantitative analysis on the basis of a net-based intermediate representation of the distributed software system under consideration. All transformations (from the distributed software system into a first Petri net model, and between the different kinds of net models) can be made formally, and therefore automated to a high degree. The evaluation of quantitative properties is based on so-called object nets which are obtained by a property-preserving structural compression and quantitative expansion of the qualitative model. In this way, the frequency and delay attributes necessary to generate quantitative models are provided by the monitoring and testing component.
Cis-diammine dichloro platinum (II) (CDDP), is a highly potent antineoplastic agent that is used in the treatment of ovarian cancer. However, the clinical use of CDDP is restricted by its severe side effects. In order to reduce these side effects and to enhance its therapeutic efficacy, we developed specific immunoconjugates consisting of the murine monoclonal antibody OC125 and CDDP, using diethylene triamine pentaacetic acid (DTPA) as a linker.
The coupling efficiencies of the different preparations synthesized, varied between 1.10±0.42 and 2.65±1.60 mol of CDDP per mol of antibody protein. Despite the chemical modification of the antibody molecule, specific binding activity of the OC125-CDDP conjugates toward the CA125 antigen was maintained as was demonstrated by means of immunohisto-/cytochemical staining of frozen sections of ovarian cancer tissue, amniotic epithelium, and the CA125 positive ovarian cancer cell line NIH:OVCAR 3.
The antiproliferative activity of the immunoconjugates was tested against the human ovarian cancer cell lines NIH:OVCAR3 and SKOV 3, applying a kinetic crystal violet microassay.
Despite the promising results obtained with the specific immuno-staining of the target cells, no significant antiproliferative activity of our immunoconjugates against the cell lines tested was observed.
One possible explanation for the lack of antitumor activity could be the fact that CA125 is released in large amounts by the NIH:OVCAR 3 cells. This may have prevented an efficient immunotargeting of the cancer cells by the formation of soluble immune complexes.
Identification of insulin and insulin-like growth factor I (IGF I) receptors in ovarian cancer
(1994)
Abstract
The objective of this study was to test if specific insulin and insulin-like growth factor I (IGF I) receptors are expressed in ovarian cancer tissue. Thirteen tissue specimens from primary ovarian cancers, 1 specimen from a primary peritoneal carcinoma, 10 specimens from metastatic lesions of ovarian carcinomas, and 4 specimens from recurrent ovarian cancers together with 13 normal ovaries were tested for their content of insulin and IGF-I receptors, by the application of specific insulin and IGF-I receptor radioimmunoassays. The insulin receptor (IR) and IGF-I receptor (IGF R) content in the primary tumors varied between 23.8-321.4 and 16.4-554.2 ng/0.1 mg DNA, respectively. Metastatic lesions contained between 12.3 and 226.7 ng IR/0.1 mg DNA and between 7.5 and 459.4 ng IGF R/0.1 mg DNA. In recurrent tumors the receptor concentrations were in the range of 41.5-79.8 and 48.9-160.9 ng/0.1 mg DNA for insulin and IGF-I receptors, respectively. Normal ovarian tissue contained between 12.2 and 150.1 ng IR and between 21.4 and 420.1 ng IGF R per 0.1 mg DNA, respectively. As both insulin and IGF-I receptors are present in ovarian cancer tissue, the effects of insulin and IGF-I as potential growth factors in ovarian cancer should be further investigated.
Copyright © 1994 Academic Press. All rights reserved.
A free boundary-value problem for a nonisothermal flow of two heavy viscous incompressible capillary liquids descibing a slot coating process is mathematically studied. The problem is stationary and two-dimensional and the Boussinesq approximation for the Navier-Stokes equations is used. The existence and uniqueness of a weak solution is proved in weighted Holder spaces for small data.
Deduktionssysteme
(1994)
Exact solutions of generalized three-particle Bargmann-Wigner equations in the strong-coupling limit
(1994)
In this paper a Petri net based methodology is outlined for an integrated qualitative and quantitative analysis of parallel software systems which is based on different (Petri) net representations of die software system under consideration. The software validation methodology starts from the source text of a set of communicating processes which specify the system under development. From this source text skeleton, a Petri net representation of the general control structure of the system is generated. On this basis a set of reduction steps is defined for transforming the net into different intermediate representations all owing the validation of both qualitative and qualitative properties. Particular attention is paid to the validation of quantitative properties which is performed using a transformation into locally Markovian Object Nets (MONs). Models of this new class of modular Petri nets are obtained by property-preserving structural compression and by enhancement with quantitative i nformation This information is obtained in the form of frequency and delay parameters by monitoring testing the software on the basis of prototypes. Compared to a previous paper on the same topic /Heiner94/ the methodology as well presentation have been improved. In particular, a new, more comprehensive running example been selected and the object net approach is explained in much more detail.
Small sodium and silver particles were generated on dielectric substrates like LiF, quartz and sapphire under ultrahigh vacuum conditions. The optical transmission spectra of the clusters were measured as a function of cluster size and shape, for low and high substrate temperatures as well as for s- and p- polarization of the incident light. Excitation of dipolar surface plasmon oscillations in the directions normal and parallel to the substrate surface could be identified. Furthermore, optical spectra for Na and Ag clusters were calculated with the classical Mie theory. The measured spectra vary strongly if the experimental conditions are changed and can be exploited, for example, to characterize the particles with regard to their size and shape. In particular, the axial ratio of the spheroidal clusters could be determined. Its value is considerably different for the two investigated metals and depends on the substrate material. Furthermore, the temperature of the substrate has a pronounced influence on the shape of the particles. At low temperature of T=100 K two-dimensional island growth is predominant. The particles extend only little in the direction perpendicular to the surface and coalesce readily at small coverage of metal atoms. In contrast, the clusters are truly three-dimensional at T=300 K. At this stage, sodium particles still exhibit a rather small axial ratio whereas silver clusters appear almost spherical. Thus, measurements of the optical spectra permit direct in situ monitoring of cluster growth during the nucleation of adsorbed atoms and of temperature induced shape variations. In addition to investigations of the shape of the particles, the quadrupolar surface plasmon mode was observed for Ag clusters.
Imaging Pattern Formation in Surface Reactions from Ultrahigh Vacuum up to Atmospheric Pressures
(1995)
Two optical methods that allow pattern formation to be investigated at an arbitrary pressure are here applied to image concentration patterns of adsorbed species associated with heterogeneous catalytic reactions. In contrast to most surface physical techniques, these methods are not restricted to high vacuum conditions and thus bridge the “pressure gap.” With carbon monoxide oxidation on a (110) surface of platinum as an example, the coupling mechanisms responsible for spatiotemporal self-organization in surface reactions were followed from reaction-diffusion control to the thermokinetic region, associated with phenomena not previously observed in pattern formation.
Two surface-sensitive optical imaging methods, Ellipso-Microscopy for surface Imaging (EMSI) and Reflection Anisotropy Microscopy (RAM) are introduced. They allow imaging of pattern formation on surfaces, e.g., due to submonolayer coverages of adsorbates, at any arbitrary pressure.
In spatio-temporal pattern formation during heterogeneously catalysed reactions this bridges the ‘pressure gap’ between well-defined UHV experiments and ‘real catalysis’. For the CO oxidation on Pt(110), the parameter space for pattern formation was extended up to 100 mbar, i.e., by 5 orders of magnitude compared to earlier investigations by Photo-Emission Electron Microscopy (PEEM) which had to be conducted below 10−3 mbar. With increasing pressure, the synchronisation mechanisms responsible for the observed pattern showed a gradual shift from reaction-diffusion to thermal-kinetic coupling unveiling previously unseen features of pattern formation in catalysis.
Analysis of a nonisothermal viscous flow problem with free boundaries and a dynamic contact line
(1995)
Effective dynamics in a subfermion shell model of leptons, quarks and electroweak gauge bosons
(1995)
Beschreibung finiter plastischer Deformationen von Einkristallen mittels materieller Isomorphismen
(1995)
Projektbericht Stadtmarketing : Ergebnisse einer Passantenbefragung in Brandenburg an der Havel
(1996)
Modular process nets are a graphical and formal notation for the representation of technical and business process models containing concurrent activities. Originally this class of Petri nets was developed for the modeling, analysis, simulation and control of workflows and computer-based process control systems, but it is also suitable for use in all other areas where a formal but comprehensible description of complex processes is needed. After a description of the basic aims and design decisions for modular process nets, the report gives a brief introduction to low-level Petri nets including different types of transition rules and aspects of the descriptive and prescriptive use of process models. The main and most innovative points which are explained in more detail are the introduction of a hierarchical module concept for nets and the definition of elementare process nets. The module concept is part of a more general ("object-based") approach to Petri nets allowing severaltypes of ab straction, whereas the main points of elementary process nets are synchronous and asynchronous communication between separately interpreted net instances via events and token passing. Modular process nets are low-level Petri nets equipped with these module and communication concepts and optionally enhanced by die use of a task concept, a method known from the areas of computer-supported cooperative work (CSCW) and work-flow management. Because the report is aimed at a systematic and easy-to-understand introduction to modular process nets, it provides a precise explanation of this net class which is kept as informal as possible and enhanced by some typical application examples