Showing papers by "Fraunhofer Society published in 2006"

Point by point comparison of two thermosensitive polymers exhibiting a similar LCST: is the age of poly(NIPAM) over?

Abstract: The present Communication compares the thermosensitivity in dilute aqueous solutions of well-defined copolymers composed of 95% of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and 5% of oligo(ethylene glycol) methacrylate (OEGMA, Mn = 475 g·mol-1) and poly(N-isopropylacrylamide) (PNIPAM) samples having similar degrees of polymerization and chain-ends. The thermoresponsive behavior of P(MEO2MA-co-OEGMA) was found to be overall comparable, and in some cases, superior to PNIPAM. Hence, P(MEO2MA-co-OEGMA) copolymers can be considered as ideal structures, which combine both the properties of poly(ethylene glycol) and PNIPAM in a single macromolecule.

Ecotoxic effect of photocatalytic active nanoparticles (TiO2) on algae and daphnids.

Abstract: Background, Aim and Scope Due to their large potential for manifold applications, the use of nanoparticles is of increasing importance. As large amounts of nanoparticles may reach the environment voluntarily or by accident, attention should be paid on the potential impacts on the environment. First studies on potential environmental effects of photocatalytic TiO2 nanoparticles have been performed on the basis of widely accepted, standardized test systems which originally had been developed for the characterization of chemicals. The methods were adapted to the special requirements of testing photocatalytic nanoparticles. Materials and Methods: Suspensions of two different nanoparticles were illuminated to induce their photocatalytic activity. For testing, the growth inhibition test with the green alga Desmodesmus subspicatus and the immobilization test with the daphnid Daphnia magna were selected and performed following the relevant guidelines (algae: ISO 8692, OECD 201, DIN 38412-33; daphnids: ISO 6341, OECD 202, DIN 38412-30). The guidelines were adapted to meet the special requirements for testing photocatalytic nanoparticles. Results: The results indicate that it is principally possible to determine the ecotoxicity of nanoparticles. It was shown that nanoparticles may have ecotoxicological effects which depend on the nature of the particles. Both products tested differ in their toxicity. Product 1 shows a clear concentration-effect curve in the test with algae (EC50: 44 mg/L). It could be proven that the observed toxicity was not caused by accompanying contaminants, since the toxic effect was comparable for the cleaned and the commercially available product. For product 2, no toxic effects were determined (maximum concentration: 50 mg/L). In the tests with daphnids, toxicity was observed for both products, although the concentration effect-curves were less pronounced. The two products differed in their toxicity; moreover, there was a difference in the toxicity of illuminated and non-illuminated products. Discussion: Both products differ in size and crystalline form, so that these parameters are assumed to contribute to the different toxicities. The concentration-effect curves for daphnids, which are less-pronounced than the curves obtained for algae, may be due to the different test organisms and/or the differing test designs. The increased toxicity of pre-illuminated particles in the tests with daphnids demonstrates that the photocatalytic activity of nanoparticles lasts for a period of time. Conclusions: The following conclusions can be drawn from the test results: (I) It is principally possible to determine the ecotoxicity of (photocatalytic) nanoparticles. Therefore, they can be assessed using methods comparable to the procedures applied for assessing soluble chemicals. - (II) Nanoparticles may exert ecotoxicological effects, which depend on the specific nanoparticle. - (III) Comparable to traditional chemicals, the ecotoxicity depends on the test organisms and their physiology. - (IV) The photocatalytic activity of nanoparticles lasts for a relevant period of time. Therefore, pre-illumination may be sufficient to detect a photocatalytic activity even by using test organisms which are not suitable for application in the pre-illumination-phase. Recommendations and Perspectives: First results are presented which indicate that the topic 'ecotoxicity and environmental effects of nanoparticles' should not be neglected. In testing photocatalytic nanoparticles, there are still many topics that need clarification or improvement, such as the cause for an observed toxicity, the improvement of the test design, the elaboration of a test battery and an assessment strategy. On the basis of optimized test systems, it will be possible to test nanoparticles systematically. If a potential risk by specific photocatalytic particles is known, a risk-benefit analysis can be performed and, if required, risk reducing measures can be taken.

3D Video and Free Viewpoint Video - Technologies, Applications and MPEG Standards

Abstract: An overview of 3D and free viewpoint video is given in this paper with special focus on related standardization activities in MPEG. Free viewpoint video allows the user to freely navigate within real world visual scenes, as known from virtual worlds in computer graphics. Examples are shown, highlighting standards conform realization using MPEG-4. Then the principles of 3D video are introduced providing the user with a 3D depth impression of the observed scene. Example systems are described again focusing on their realization based on MPEG-4. Finally multi-view video coding is described as a key component for 3D and free viewpoint video systems. The conclusion is that the necessary technology including standard media formats for 3D and free viewpoint is available or will be available in the near future, and that there is a clear demand from industry and user side for such applications. 3D TV at home and free viewpoint video on DVD will be available soon, and will create huge new markets

Polymeric Betaines: Synthesis, Characterization, and Application

Abstract: This review summarizes mostly the literature data accumulated during the last decade on betaine-type polyampholytes. Synthetic pathways to polybetaines consisting of radical polymerization, the Michael addition reaction, and polymer-analogous transformation are discussed together with methods of controlled polymerization, such as group transfer polymerization, atomic transfer radical polymerization, and reversible addition fragmentation transfer. The role of intra- and interchain associates resulting in insolubility in pure water due to the formation of ionically cross-linked network structures, and solubility in saline water because of the disruption of the ionic networks, are outlined. Attention is also paid to the recent advancement of hydrophobically modified polymeric betaines with emphasis on phospholipid-containing vinyl polymers. Polymer complexes of polybetaines, in particular interpolyelectrolyte, polymer–surfactant, and polymer–metal complexes, are considered in the light of the competition between intra- and intermolecular ionic contacts and the cooperative character of interactions. Stimuli-sensitive behavior and morphological changes of polybetaine hydrogels triggered by changes of the pH, ionic strength, water–organic solvent mixture, metal complexation, and DC electric field are discussed with respect to the ionization state of the macromolecules and the thermodynamic quality of solvents, as well as osmotic, chelating, and polarization effects. Some application aspects of polybetaines in medicine, biotechnology, hydrometallurgy, and the oil industry are also discussed.

Micro-optical artificial compound eyes.

Abstract: Natural compound eyes combine small eye volumes with a large field of view at the cost of comparatively low spatial resolution. For small invertebrates such as flies or moths, compound eyes are the perfectly adapted solution to obtaining sufficient visual information about their environment without overloading their brains with the necessary image processing. However, to date little effort has been made to adopt this principle in optics. Classical imaging always had its archetype in natural single aperture eyes which, for example, human vision is based on. But a high-resolution image is not always required. Often the focus is on very compact, robust and cheap vision systems. The main question is consequently: what is the better approach for extremely miniaturized imaging systems—just scaling of classical lens designs or being inspired by alternative imaging principles evolved by nature in the case of small insects? In this paper, it is shown that such optical systems can be achieved using state-of-the-art micro-optics technology. This enables the generation of highly precise and uniform microlens arrays and their accurate alignment to the subsequent optics-, spacing- and optoelectronics structures. The results are thin, simple and monolithic imaging devices with a high accuracy of photolithography. Two different artificial compound eye concepts for compact vision systems have been investigated in detail: the artificial apposition compound eye and the cluster eye. Novel optical design methods and characterization tools were developed to allow the layout and experimental testing of the planar micro-optical imaging systems, which were fabricated for the first time by micro-optics technology. The artificial apposition compound eye can be considered as a simple imaging optical sensor while the cluster eye is capable of becoming a valid alternative to classical bulk objectives but is much more complex than the first system.

In vivo assessment of human skin aging by multiphoton laser scanning tomography

Abstract: Changes of dermal collagen and elastin content are characteristic for skin aging as well as for pathological skin conditions. To evaluate these changes, we used in vivo multiphoton laser tomography to measure two-photon excited autofluorescence (AF) and second harmonic generation (SHG). We tested 18 patients of all ages and calculated the SHG-to-AF aging index of dermis (SAAID). We observed a negative relationship between the SAAID and age, which was accelerated for the female (n=7) subgroup. The current findings are the first in vivo demonstration of this relationship, and they show that specific characteristics of aged skin such as the ratio of extracellular matrix components collagen and elastin can be evaluated by in vivo AF and SHG measurements using near-IR femtosecond laser pulses.

Rationale Management in Software Engineering

Abstract: This is a detailed summary of research on design rationale providing researchers in software engineering with an excellent overview of the subject. Professional software engineers will find many examples, resources and incentives to enhance their ability to make decisions during all phases of the software lifecycle. Software engineering is still primarily a human-based activity and rationale management is concerned with making design and development decisions explicit to all stakeholders involved.

Cobalt in hard metals and cobalt sulfate, gallium arsenide, indium phosphide and vanadium pentoxide

Abstract: Members Mario Altamirano-Lozano, Unidad de Investigación en Genética y Toxicología Ambiental (UNIGEN), Facultad de Estudios Superiores-Zaragoza, Battalla del 5 de mayo esq. Fuerte de Loreto Col. Ejercito de Oriente, C.P. 09230 Mexico, DF, Mexico Detmar Beyersmann, Department of Biology & Chemistry, Fachbereich 2, University of Bremen, Leobener Strasse NW2, Raum B2230, 28359 Bremen, Germany (Chairman) Dean E. Carter, Department of Pharmacology & Toxicology, Center for Toxicology, College of Pharmacy, University of Arizona, 1703 E. Mabel, Tucson, AZ 85721, USA (unable to attend) Bruce A. Fowler, Senior Research Advisor, ATSDR/CDC, 1600 Clifton Road NE, MS E-29, Atlanta, GA 30333, USA (Subgroup Chair: Other Relevant Data) Bice Fubini, Department of Inorganic, Physical & Material Chemistry and Interdepartmental Center ‘G. Scansetti’ for Studies on Asbestos and other Toxic Particulates, Facoltà di Farmacia, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino, Italy Janet Kielhorn, Fraunhofer Institute of Toxicology & Experimental Medicine, Department of Chemical Risk Assessment, Nikolai-Fuchs-Strasse 1, 30625 Hannover, Germany Micheline Kirsch-Volders, Laboratorium voor Cellulaire Genetica, Faculteit Wetenschappen, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Jan Kucera, Nuclear Physics Institute, 250 68 Rez near Prague, Czech Republic Yukinori Kusaka, Department of Environmental Health, School of Medicine, Fukui Medical University, Matsuoka-cho, Fukui 910-1193, Japan (Subgroup Chair: Exposure Data) Gerard Lasfargues, Médecine et Santé au Travail, Faculté de Médecine, 2 bis Bd Tonnelé, B.P. 3223, 37325 Tours Cedex, France Dominique Lison, Industrial Toxicology & Occupational Medicine Unit, Catholic University of Louvain, Clos Chapelle-aux-Champs 30, 1200 Brussels, Belgium IARC WORKING GROUP ON THE EVALUATION OF CARCINOGENIC RISKS TO HUMANS: COBALT IN HARD METALS AND COBALT SULFATE, GALLIUM ARSENIDE, INDIUM PHOSPHIDE AND VANADIUM PENTOXIDE

An experimental comparison of audio tempo induction algorithms

Abstract: We report on the tempo induction contest organized during the International Conference on Music Information Retrieval (ISMIR 2004) held at the University Pompeu Fabra in Barcelona, Spain, in October 2004. The goal of this contest was to evaluate some state-of-the-art algorithms in the task of inducing the basic tempo (as a scalar, in beats per minute) from musical audio signals. To our knowledge, this is the first published large scale cross-validation of audio tempo induction algorithms. Participants were invited to submit algorithms to the contest organizer, in one of several allowed formats. No training data was provided. A total of 12 entries (representing the work of seven research teams) were evaluated, 11 of which are reported in this document. Results on the test set of 3199 instances were returned to the participants before they were made public. Anssi Klapuri's algorithm won the contest. This evaluation shows that tempo induction algorithms can reach over 80% accuracy for music with a constant tempo, if we do not insist on finding a specific metrical level. After the competition, the algorithms and results were analyzed in order to discover general lessons for the future development of tempo induction systems. One conclusion is that robust tempo induction entails the processing of frame features rather than that of onset lists. Further, we propose a new "redundant" approach to tempo induction, inspired by knowledge of human perceptual mechanisms, which combines multiple simpler methods using a voting mechanism. Machine emulation of human tempo induction is still an open issue. Many avenues for future work in audio tempo tracking are highlighted, as for instance the definition of the best rhythmic features and the most appropriate periodicity detection method. In order to stimulate further research, the contest results, annotations, evaluation software and part of the data are available at http://ismir2004.ismir.net/ISMIR_Contest.html

Interactive 3-DTV-Concepts and Key Technologies

Abstract: The objective of this paper is to provide an overview about recent trends in the area of three-dimensional television (3-DTV). This includes the application of new 3-D data representation formats, which are inherently interactive and more flexible than the traditional (two-view) stereoscopic image. In this context, we describe an experimental 3-DTV system that is based on the joint distribution of monoscopic color video and associated per-pixel depth information. From these data, one or more “virtual” views of a real-world scene can be synthesized in real-time at the receiver side (i.e., in a 3-DTV set-top box) by means of so-called depth-image-based rendering (DIBR) techniques. In addition, the paper provides details on the latest advances in glasses-free (autostereoscopic) 3-DTV display development, both for single and multiple users, as well as on multimodel user interfaces based on head, gaze, or gesture tracking.

Novel cellulose fibre reinforced thermoplastic materials

Abstract: Spun cellulose fibres from the viscose, lyocell and carbamate processes have been used to reinforce thermoplastic commodity polymers, such as polypropylene (PP), polyethylene (PE) and (high impact) polystyrene (HIPS) as well as poly(lactic acid) (PLA) and a thermoplastic elastomer (TPE) for injection moulding applications. A specially developed double pultrusion technique has been employed for compounding. Fibres were analysed in single fibre tensile tests. Strength, stiffness, impact strength, and heat distortion temperature (HDT) were determined for injection-moulded standard test specimen and structural features were revealed by scanning electron microscopy. A strong reinforcing effect was observed in all cases. In particular, high tenacity tyre cord rayon gives excellent composite strength and impact strength, often doubling or tripling the pristine matrix values. In the case of PP, Lyocell type fibres provide enhanced stiffness and HDT, and thus the combination of both fibre types leads to a balanced composite property profile. The PE case is very similar to PP. For HIPS mainly strength and stiffness is increased, while for TPE the property profile is changed completely. With PLA, a biogenic and biodegradable composite with excellent mechanical properties is presented.

Coupling of mesh‐free methods with finite elements: basic concepts and test results

Abstract: SUMMARY This paper reviews several novel and older methods for coupling mesh-free particle methods, particularly the element-free Galerkin (EFG) method and the smooth particle hydrodynamics (SPH), withnite elements (FEs). We study master-slave couplings where particles arexed across the FE boundary, coupling via interface shape functions such that consistency conditions are satised, bridging domain coupling, compatibility coupling with Lagrange multipliers and hybrid coupling methods where forces from the particles are applied via their shape functions on the FE nodes and vice versa. The hybrid coupling methods are well suited for large deformations and adaptivity and the coupling procedure is independent of the particle distance and nodal arrangement. We will study the methods for several static and dynamic applications, compare the results to analytical and experimental data and show advantages and drawbacks of the methods. Copyright ? 2006 John Wiley & Sons, Ltd.

Application of piezoelectric layers in electrostatic MEM actuators: controlling of pull-in voltage

Abstract: In this paper, a novel method has been developed to control the pull-in voltage of the fixed-fixed and cantilever MEM actuators and measure the residual stress in the fixed-fixed model using of the piezoelectric layers that have been located on the upper and lower surfaces of actuator. In the developed model, the tensile or compressive residual stresses, fringing-field and axial stress effects in the fixed-fixed end type micro-electro-mechanical systems actuator have been considered. The non-linear governing differential equations of the MEM actuators have been derived by considering the piezoelectric layers and mentioned effects. The results show that due to different applied voltage to the piezoelectric layers, the pull-in voltage can be controlled and in the fixed-fixed type the unknown value of the residual stress can be obtained.

Visual Observation of Zener Tunneling

Abstract: We experimentally investigate photonic Zener tunneling between the bands of a waveguide array by directly monitoring the propagating light inside this structure. For strong transverse index gradients we observe Zener breakdown as regular outbursts of radiation escaping from the Bloch oscillations. Tunneling to higher order photonic bands and Bloch oscillations in different bands have been detected.

Lung fibroblasts from patients with emphysema show markers of senescence in vitro.

Abstract: The loss of alveolar walls is a hallmark of emphysema. As fibroblasts play an important role in the maintenance of alveolar structure, a change in fibroblast phenotype could be involved in the pathogenesis of this disease. In a previous study we found a reduced in vitro proliferation rate and number of population doublings of parenchymal lung fibroblasts from patients with emphysema and we hypothesized that these findings could be related to a premature cellular aging of these cells. In this study, we therefore compared cellular senescence markers and expression of respective genes between lung fibroblasts from patients with emphysema and control patients without COPD. Primary lung fibroblasts were obtained from 13 patients with moderate to severe lung emphysema (E) and 15 controls (C) undergoing surgery for lung tumor resection or volume reduction (n = 2). Fibroblasts (8E/9C) were stained for senescence-associated β-galactosidase (SA-β-Gal). In independent cultures, DNA from lung fibroblasts (7E/8C) was assessed for mean telomere length. Two exploratory 12 k cDNA microarrays were used to assess gene expression in pooled fibroblasts (3E/3C). Subsequently, expression of selected genes was evaluated by quantitative PCR (qPCR) in fibroblasts of individual patients (10E/9C) and protein concentration was analyzed in the cell culture supernatant. The median (quartiles) percentage of fibroblasts positive for SA-β-Gal was 4.4 (3.2;4.7) % in controls and 16.0 (10.0;24.8) % in emphysema (p = 0.001), while telomere length was not different. Among the candidates for differentially expressed genes in the array (factor ≥ 3), 15 were upregulated and 121 downregulated in emphysema. qPCR confirmed the upregulation of insulin-like growth factor-binding protein (IGFBP)-3 and IGFBP-rP1 (p = 0.029, p = 0.0002), while expression of IGFBP-5, -rP2 (CTGF), -rP4 (Cyr61), FOSL1, LOXL2, OAZ1 and CDK4 was not different between groups. In line with the gene expression we found increased cell culture supernatant concentrations of IGFBP-3 (p = 0.006) in emphysema. These data support the hypothesis that premature aging of lung fibroblasts occurs in emphysema, via a telomere-independent mechanism. The upregulation of the senescence-associated IGFBP-3 and -rP1 in emphysema suggests that inhibition of the action of insulin and insulin-like growth factors could be involved in the reduced in vitro-proliferation rate.

Efficient Compression of Multi-View Video Exploiting Inter-View Dependencies Based on H.264/MPEG4-AVC

Abstract: Efficient Multi-view coding requires coding algorithms that exploit temporal, as well as inter-view dependencies between adjacent cameras. Based on a spatiotemporal analysis on the multi-view data set, we present a coding scheme utilizing an H.264/MPEG4-AVC codec. To handle the specific requirements of multi-view datasets, namely temporal and inter-view correlation, two main features of the coder are used: hierarchical B pictures for temporal dependencies and an adapted prediction scheme to exploit inter-view dependencies. Both features are set up in the H.264/MPEG4-AVC configuration file, such that coding and decoding is purely based on standardized software. Additionally, picture reordering before coding to optimize coding efficiency and inverse reordering after decoding to obtain individual views are applied. Finally, coding results are shown for the proposed multi-view coder and compared to simulcast anchor and simulcast hierarchical B picture coding.

Microbial degradation of nonylphenol and other alkylphenols—our evolving view

Abstract: Because the endocrine disrupting effects of nonylphenol (NP) and octylphenol became evident, the degradation of long-chain alkylphenols (AP) by microorganisms was intensively studied. Most NP-degrading bacteria belong to the sphingomonads and closely related genera, while NP metabolism is not restricted to defined fungal taxa. Growth on NP and its mineralization was demonstrated for bacterial isolates, whereas ultimate degradation by fungi still remains unclear. While both bacterial and fungal degradation of short-chain AP, such as cresols, and the bacterial degradation of long-chain branched AP involves aromatic ring hydroxylation, alkyl chain oxidation and the formation of phenolic polymers seem to be preferential elimination pathways of long-chain branched AP in fungi, whereby both intracellular and extracellular oxidative enzymes may be involved. The degradation of NP by sphingomonads does not proceed via the common degradation mechanisms reported for short-chain AP, rather, via an unusual ipso-substitution mechanism. This fact underlies the peculiarity of long-chain AP such as NP isomers, which possess highly branched alkyl groups mostly containing a quaternary α-carbon. In addition to physicochemical parameters influencing degradation rates, this structural characteristic confers to branched isomers of NP a biodegradability different to that of the widely used linear isomer of NP. Potential biotechnological applications for the removal of AP from contaminated media and the difficulties of analysis and application inherent to the hydrophobic NP, in particular, are also discussed. The combination of bacteria and fungi, attacking NP at both the phenolic and alkylic moiety, represents a promising perspective.

Denial of service attacks targeting a SIP VoIP infrastructure: attack scenarios and prevention mechanisms

Abstract: In this article we address the issue of denial of service attacks targeting the hardware and software of voice over IP servers or by misusing specific signaling protocol features. As a signaling protocol we investigate here the session initiation protocol. In this context we mainly identify attacks based on exhaustion of the memory of VoIP servers, or attacks that incur high CPU load. We deliver an overview of different attack possibilities and explain some attacks in more detail, including attacks utilizing the DNS system and those targeting the parser. A major conclusion of the work is the knowledge that SIP provides a wide range of features that can be used to mount DoS attacks. Discovering these attacks is inherently difficult, as is the case with DoS attacks on other IP components. However, with adequate server design, efficient implementation, and appropriate hardware, the effects of a large portion of attacks can be reduced

Single channel 1.28 Tbit/s and 2.56 Tbit/s DQPSK transmission

Abstract: By combining the techniques of optical TDM with polarisation multiplexing and DQPSK modulation format, 240 km transmission of 1.28 Tbit/s and 160 km transmission of 2.56 Tbit/s has been performed in a single wavelength channel.