Showing papers by "University of Paderborn published in 2007"
TL;DR: It is shown how the distortion of the desired signal can be controlled by a single-channel post-filter, resulting in a performance comparable to the generalized minimum variance distortionless response beamformer, where arbitrary transfer functions relate the source and the microphones.
Abstract: Maximizing the output signal-to-noise ratio (SNR) of a sensor array in the presence of spatially colored noise leads to a generalized eigenvalue problem. While this approach has extensively been employed in narrowband (antenna) array beamforming, it is typically not used for broadband (microphone) array beamforming due to the uncontrolled amount of speech distortion introduced by a narrowband SNR criterion. In this paper, we show how the distortion of the desired signal can be controlled by a single-channel post-filter, resulting in a performance comparable to the generalized minimum variance distortionless response beamformer, where arbitrary transfer functions relate the source and the microphones. Results are given both for directional and diffuse noise. A novel gradient ascent adaptation algorithm is presented, and its good convergence properties are experimentally revealed by comparison with alternatives from the literature. A key feature of the proposed beamformer is that it operates blindly, i.e., it neither requires knowledge about the array geometry nor an explicit estimation of the transfer functions from source to sensors or the direction-of-arrival.
233 citations
TL;DR: The growing economic importance of professional football and the recent fundamental changes in the regulatory regime governing the football players' labor market together with the availability of detailed information on player salaries, transfer fees and contract lengths have convinced an increasing number of economists from all over Europe to devote their attention to the operation of that particular market as discussed by the authors.
Abstract: The growing economic importance of professional football and the recent fundamental changes in the regulatory regime governing the football players' labor market together with the availability of detailed information on player salaries, transfer fees and contract lengths have convinced an increasing number of economists from all over Europe to devote their attention to the operation of that particular market. The following paper reviews the available evidence on the various dimensions of that market (remuneration, transfers, contracts and mobility) and points out some promising directions for further research.
228 citations
06 Jun 2007
TL;DR: Every unweighted point set P has a weak coreset of size Poly(k,1/ε) for the k-means clustering problem, i.e. its size is independent of the cardinality |P| of the point set and the dimension d of the Euclidean space Rd.
Abstract: Given a point set P ⊆ Rd the k-means clustering problem is to find a set C=(c1,...,ck) of k points and a partition of P into k clusters C1,...,Ck such that the sum of squared errors ∑i=1k ∑p ∈ Ci |p -ci |22 is minimized. For given centers this cost function is minimized byassigning points to the nearest center.The k-means cost function is probably the most widely used cost function in the area of clustering.In this paper we show that every unweighted point set P has a weak (e, k)-coreset of size Poly(k,1/e) for the k-means clustering problem, i.e. its size is independent of the cardinality |P| of the point set and the dimension d of the Euclidean space Rd. A weak coreset is a weighted set S ⊆ P together with a set T such that T contains a (1+e)-approximation for the optimal cluster centers from P and for every set of kcenters from T the cost of the centers for S is a (1±e)-approximation of the cost for P.We apply our weak coreset to obtain a PTAS for the k-means clustering problem with running time O(nkd + d · Poly(k/e) + 2O(k/e)).
214 citations
TL;DR: Results show that the DFTB method with the present parameters reproduces structural properties very well, but the bond energies and the relative energies of different spin states only qualitatively compared to the B3LYP/SDD+6-31G(d) density functional (DFT) results.
Abstract: Recently developed parameters for five first-row transition-metal elements (M = Sc, Ti, Fe, Co, and Ni) in combination with H, C, N, and O as well as the same metal (M−M) for the spin-polarized self-consistent-charge density-functional tight-binding (DFTB) method have been calibrated. To test their performance a couple sets of compounds have been selected to represent a variety of interactions and bonding schemes that occur frequently in transition-metal containing systems. The results show that the DFTB method with the present parameters in most cases reproduces structural properties very well, but the bond energies and the relative energies of different spin states only qualitatively compared to the B3LYP/SDD+6-31G(d) density functional (DFT) results. An application to the ONIOM(DFT:DFTB) indicates that DFTB works well as the low level method for the ONIOM calculation.
199 citations
TL;DR: The interesting and most usefull knowledge on lapachol, which is reviewed in this paper, can be used as a starting point in future research endeavors.
Abstract: Lapachol is a naphthoquinone that was first isolated by E. Paterno from Tabebuia avellanedae (Bignoniaceae) in 1882. A wide spectrum of therapeutic activities have been attributed to lapachol or its derivatives viz., anti-abscess, anti-ulcer, antileishmanial, anticarcinomic, anti- edemic, anti-inflammatory, antimalarial, antiseptic, antitumor, antiviral, bactericidal, fungicidal, insectifugal, pesticidal, protisticidal, respiradepressant, schistosomicidal, termiticidal, and viricidal. Originally isolated from species of the Bignoniaceae family, lapachol can also be found in other families such as Verbenaceae, Proteaceae, Leguminosae, Sapotaceae, Scrophulariaceae, and Malvaceae. The interesting and most usefull knowledge on lapachol, which is reviewed in this paper, can be used as a starting point in future research endeavors.
188 citations
TL;DR: In this article, the decay curves of Sm3-doped phosphate and fluorophosphate glasses are perfectly single exponential for lower concentration (0.01) and gradually change to non-exponential for higher concentrations.
181 citations
TL;DR: This Letter pursues a novel, more direct approach to uncover coherent regions in the surface ocean using high-resolution model velocity data based upon numerically constructing a transfer operator that controls the surface transport of particles over a short period.
Abstract: Coherent nondispersive structures are known to play a crucial role in explaining transport in nonautonomous dynamical systems such as ocean flows. These structures are difficult to extract from model output as they are Lagrangian by nature and not revealed by the underlying Eulerian velocity fields. In the last few years heuristic concepts such as finite-time Lyapunov exponents have been used in an attempt to detect barriers to oceanic transport and thus identify regions that trap material such as nutrients and phytoplankton. In this Letter we pursue a novel, more direct approach to uncover coherent regions in the surface ocean using high-resolution model velocity data. Our method is based upon numerically constructing a transfer operator that controls the surface transport of particles over a short period. We apply our technique to the polar latitudes of the Southern Ocean.
166 citations
TL;DR: In this paper, the second and fourth rank crystal field (CF) parameters have been calculated together with the CF strength parameter by assuming the C2v symmetry for the Eu3+ ions in both the phosphate and fluorophosphate glasses.
165 citations
TL;DR: The results of these findings might indicate differences in focused attention with involvement of the anterior cingulate cortex (frontal Theta) and sensory processing in the parietal somatosensory cortex (Alpha‐2).
Abstract: After reconstruction of the anterior cruciate ligament (ACL) afferent proprioceptive information from the knee joint may be altered. In order to examine changes in central activation patterns, spectral features of the electroencephalography (EEG) were measured. Patients after ACL reconstruction and healthy controls carried out an knee-angle reproduction task in a groups x limbs x trials design. Cortical activity was recorded using international standards. FFT were conducted to determine power at Theta, Alpha-1, Alpha-2 and Beta-1. Statistics show significantly larger aberrations in the reconstructed limbs compared with the controls whereas there are no differences between the uninvolved land controls. Brain activity demonstrates significantly higher frontal Theta-power (F3, F4, F8) in both limbs of the ACL group vs the controls and a significantly higher Alpha-2 power was shown in the ACL-reconstructed limb compared with controls at parietal positions (P3, P4). No such differences were found between the uninvolved side and the controls. The EEG was able to measure a change in joint position sense at the cortical level after the reconstruction of the ACL. The results of these findings might indicate differences in focused attention with involvement of the anterior cingulate cortex (frontal Theta) and sensory processing in the parietal somatosensory cortex (Alpha-2).
145 citations
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TL;DR: In this article, the authors employ a model of endogenous foreign subsidiary ownership to derive a set of empirically testable hypotheses about the differential taxation of foreign and domestically-owned subsidiaries.
Abstract: This paper analyzes to which extent foreign plant ownership involves lower tax payments than domestic plant ownership. We employ a model of endogenous foreign subsidiary ownership to derive a set of empirically testable hypotheses about the differential taxation of foreign- and domestically-owned subsidiaries. We assess these hypotheses in a data- set of 33,577 European foreign- and domestically-owned manufacturing plants. We identify a significant tax-saving of endogenous foreign owner- ship. On average, foreign owners pay 594 Euros per employee or about 56 percent less than domestic owners of similar subsidiaries. This effect is larger in thinner markets with fewer plants, in markets with a greater relative presence of foreign owners, and for foreign owners of larger plants.
139 citations
TL;DR: In this paper, LiNbO3 ridge waveguides were fabricated using a mixture of HF and HNO3 using chromium (Cr) stripes as masks and smooth etched surfaces were obtained by adding some ethanol into the etchant.
Abstract: The fabrication of LiNbO3 ridge waveguides etched by a mixture of HF and HNO3 using chromium (Cr) stripes as masks is reported. Smooth etched surfaces are obtained by adding some ethanol into the etchant. Under-etching is nearly avoided by annealing the sample with the Cr masks before the wet etching process. Low-loss monomode ridge guides with a height of up to 8 mum and a width between 4.5 and 7.0 mum are demonstrated. As an example, the propagation losses in a 6.5-mum-wide and 8-mum-high structure are 0.3 dB/cm for transverse-electric and 0.9 dB/cm for transverse-magnetic polarization, respectively, at 1.55-mum wavelength
19 May 2007
TL;DR: A Process Mining Framework can be used for obtaining software process models as well as for analysing and optimising them and an algorithmic approach, which arose from research on software processes, is integrated in the framework.
Abstract: Software development processes are often not explicitly modelled and sometimes even chaotic. In order to keep track of the involved documents and files, engineers use Software Configuration Management (SCM) systems. Along the way, those systems collect and store information on the software process itself. Thus, SCM information can be used for constructing explicit process models, which is called software process mining. In this paper we show that (1) a Process Mining Framework can be used for obtaining software process models as well as for analysing and optimising them; (2) an algorithmic approach, which arose from our research on software processes, is integrated in the framework.
TL;DR: In this paper, the effect of magnetic field on the martensitic phase transformation in Ni2MnGa single crystals was investigated under compression and reversible and one-way stress-assisted field-induced phase transformations were observed under low field magnitudes.
TL;DR: 2-Chloro-N-(diethylcarbamothioyl)benzamide has been synthesized and characterized by elemental analysis and IR spectroscopy and the raw B3LYP frequencies approximate the experimental data much better than the results of Hartree-Fock.
TL;DR: The ACs initially proposed by Albers-Schönberg and Schmid are shown to be correct, and the opposite ACs recently derived from the ECD spectra of 1 and 2 by Elsässer et al. are shows to be incorrect.
Abstract: The absolute configurations (ACs) of the iridoid natural products, plumericin (1) and isoplumericin (2), have been re-investigated using vibrational circular dichroism (VCD) spectroscopy, electronic circular dichroism (ECD) spectroscopy, and optical rotatory dispersion (ORD). Comparison of DFT calculations of the VCD spectra of 1 and 2 to the experimental VCD spectra of the natural products, (+)-1 and (+)-2, leads unambiguously to the AC (1R,5S,8S,9S,10S)-(+) for both 1 and 2. In contrast, comparison of time-dependent DFT (TDDFT) calculations of the ECD spectra of 1 and 2 to the experimental spectra of (+)-1 and (+)-2 does not permit definitive assignment of their ACs. On the other hand, TDDFT calculations of the ORD of (1R,5S,8S,9S,10S)-1 and -2 over the range of 365−589 nm are in excellent agreement with the experimental data of (+)-1 and (+)-2, confirming the ACs derived from the VCD spectra. Thus, the ACs initially proposed by Albers-Schonberg and Schmid are shown to be correct, and the opposite ACs r...
06 Jun 2007
TL;DR: This paper describes how model checking can be employed for formal verification of business processes against such patterns and presents an automated transformation of the business process and the corresponding patterns into a transition system and temporal logic, respectively.
Abstract: Business processes usually have to consider certain constraints like domain specific and quality requirements. The automated formal verification of these constraints is desirable, but requires the user to provide an unambiguous formal specification. In particular since the notations for business process modeling are usually visual flow-oriented languages, the notational gap to the languages usually employed for the formal specification of constraints, e.g., temporal logic, is significant and hard to bridge. Thus, our approach relies on UML Activities as a single language for the specification of both business processes and the corresponding constraints. For the expression of such constraints, we have provided a process pattern definition language based on specialized Activities. In this paper, we describe how model checking can be employed for formal verification of business processes against such patterns. For this, we present an automated transformation of the business process and the corresponding patterns into a transition system and temporal logic, respectively.
12 Nov 2007
TL;DR: The incurred time and area overheads are investigated, especially for inter-thread communication across the hardware/-software boundary, and a case study demonstrating the feasibility of the RTOS-centric design approach is presented.
Abstract: Modern platform FPGAs integrate fine-grained reconfigurable logic with processor cores and allow the creation of complete configurable systems-on-chip. However, design methodologies have not kept up with the rise in complexity of the target hardware. In particular, there is little overlap between the programming model for embedded software running on a real-time operating system and the programming model for digital logic. In this paper, we present the operating system ReconOS which supports both software and hardware threads with a single unified programming model. ReconOS is based on eCos, a widely-used real-time operating system (RTOS). We investigate the incurred time and area overheads, especially for inter-thread communication across the hardware/-software boundary, and present a case study demonstrating the feasibility of the RTOS-centric design approach.
26 Aug 2007
TL;DR: A special case of weighted congestion games with playerspecific latency functions where each player uses for each particular resource a fixed (non-decreasing) delay function together with a player-specific constant is considered, and it is observed that this class is contained in the new intuitive class of dominance weighted congestionGames.
Abstract: We consider a special case of weighted congestion games with playerspecific latency functions where each player uses for each particular resource a fixed (non-decreasing) delay function together with a player-specific constant. For each particular resource, the resource-specific delay function and the playerspecific constant (for that resource) are composed by means of a group operation (such as addition or multiplication) into a player-specific latency function. We assume that the underlying group is a totally ordered abelian group. In this way, we obtain the class of weighted congestion games with player-specific constants; we observe that this class is contained in the new intuitive class of dominance weighted congestion games. We obtain the following results: Games on parallel links: - Every unweighted congestion game has a generalized ordinal potential. - There is a weighted congestion game with 3 players on 3 parallel links that does not have the Finite Best-Improvement Property. - There is a particular best-improvement cycle for general weighted congestion games with player-specific latency functions and 3 players whose outlaw implies the existence of a pure Nash equilibrium. This cycle is indeed outlawed for dominance weighted congestion games with 3 players - and hence for weighted congestion games with player-specific constants and 3 players. Network congestion games: For unweighted symmetric network congestion games with player-specific additive constants, it is PLS-complete to find a pure Nash equilibrium. Arbitrary (non-network) congestion games: Every weighted congestion game with linear delay functions and player-specific additive constants has a weighted potential.
20 May 2007
TL;DR: The integrated built-in test and repair approach proposed in this paper interleaves test and Repair analysis and supports an exact solution without failure bitmap, which is combined with an efficient technique to continuously reduce the problem complexity and keep the test and analysis time low.
Abstract: An efficient on-chip infrastructure for memory test and repair is crucial to enhance yield and availability of SoCs. Therefore embedded memories are commonly equipped with spare rows and columns (2D redundancy). To avoid the storage of large failure bitmaps needed by classical algorithms for offline repair analysis, existing heuristics for built-in repair analysis (BIRA) either follow very simple search strategies or restrict the search to smaller local bitmaps. Exact BIRA algorithms work with sub analyzers for each possible repair combination. While a parallel implementation suffers from a high hardware overhead, a serial implementation leads to high test times. The integrated built-in test and repair approach proposed in this paper interleaves test and repair analysis and supports an exact solution without failure bitmap. The basic search procedure is combined with an efficient technique to continuously reduce the problem complexity and keep the test and analysis time low.
TL;DR: In this article, the role of inter-martensitic transformation in creating intersecting heating and cooling segments was investigated and the authors used a thermo-mechanical formulation to rationalize the role.
01 Jan 2007
TL;DR: In this article, it was shown that intact plants can take up substantial amounts of antibiotics by the roots, translocated within the plants into stems and leaves; CTC even into the wheat grain after twofold slurry application in spring.
Abstract: Under farming conditions, winter wheat was cultivated on manure-fertilised soil. The liquid manure originated from pigs medicated under control with chlortetracycline (CTC), sulfadiazine (SFD) and trimethoprim (TMP). Dur-ing 8 months of storage the initial concentration of CTC and SFD in the manure decreased by 50 - 60 %. This ma-nure was used as a fertiliser, thereby remarkable amounts of antibiotics were administered to soil. Antibiotic recov-ery rates from soil peaked after the 2 nd slurry administra-tion (SFD: 90 µg/kg dw, CTC-compounds: 20 µg/kg dw) in the plough layer (0 - 25 cm) and dropped to a low level within to 5 months. Wheat was grown on this soil. CTC and SFD were readily taken up by the roots, translocated within the plants into stems and leaves; CTC even into the wheat grain (~ µg/kg fw) after twofold slurry application in spring. Experiments with non-labelled and H-labelled antibiotics using hydroponically grown wheat, lamb’s let-tuce and carrots corroborate the result that intact plants can take up substantial amounts of antibiotics by the roots. Our study has revealed a novel way of human exposure to vet-erinary antibiotics by plant derived food.
Abstract: Novel tree-like alumina nanopores were reproducibly obtained in non-steady-state anodization conditions by exponential decrease of anodization potential. The mechanism of pore formation was thought to be due to a combination of electrical treeing and mechanic stress in the growth process. Furthermore, some interesting properties from gold nanotrees were observed showing that the tree-like nanopores will be new templates towards fabrication of nanotrees from a variety of materials possibly exhibiting new shape-dependent properties.
04 Dec 2007
TL;DR: Network-coding- based MARC operated in adaptive mode has better performance when the quality of the source-relay links are poor, and this system has better coverage area.
Abstract: The multiple-access relay channel (MARC) based on network coding has been proposed in recent papers as a means to achieve diversity gain in wireless networks, at the same time reducing the number of transmissions by a relay node. In MARC, multiple sources transmit to a common destination with the assistance of a single relay. In a network-coding-based realization of MARC, the relay merges the messages received from the two sources and forwards them to the destination; at the destination, the sources' messages can be recovered from either their direct transmissions or by performing additional network coding. In this work, performance analysis in the form of outage probability and coverage area, when non-ideal source-relay links exist, is performed. The relay is assumed to operate either in static or adaptive mode, and comparisons with the conventional MARC and point-to-point transmission are made. The outage results show that the conventional MARC system perform better when the source-relay links are high quality. Network-coding- based MARC operated in adaptive mode has better performance when the quality of the source-relay links are poor, and this system has better coverage area.
TL;DR: By interfering photon echoes produced in a single-mode Ti:Er:LiNbO(3) waveguide, it is found that decoherence in the medium translates only as loss and not as degradation of information.
Abstract: We investigated the preservation of information encoded into the relative phase and amplitudes of optical pulses during storage and retrieval in an optical memory based on stimulated photon echo. By interfering photon echoes produced in a Ti-indiffused single-mode Er-doped LiNbO$_{3}$ waveguiding structure at telecom wavelength, we found that decoherence in the atomic medium translates only as losses (and not as degradation) of information, as long as the data pulse series is short compared to the atomic decoherence time. The experimentally measured value of the visibility for interfering echoes is close to 100 %. In addition to the expected three-pulse photon-echo interferences we also observed interference due to a four-pulse photon echo. Our findings are of particular interest for future long-distance quantum communication protocols, which rely on the reversible transfer of quantum states between light and atoms with high fidelity.
23 Jul 2007
TL;DR: The fuzzy video based emotion recognition system VISBER, that allows to analyze facial expressions in video sequences and supports the automatic adaptation to the characteristics of individual human faces by a short training phase that can be done before the emotion recognition starts.
Abstract: This paper presents the fuzzy video based emotion recognition system VISBER, that allows to analyze facial expressions in video sequences. In order to process images in real-time a tracking mechanism is used for face localization. The fuzzy classification itself analyzes the deformation of a face separately in each image. In contrast to most existing approaches, also blended emotions with varying intensities as proposed by psychologists can be handled. For this purpose we propose a fuzzy emotion model which is generally applicable for also for other emotion recognition solutions. Furthermore, VISBER supports the automatic adaptation to the characteristics of individual human faces by a short training phase that can be done before the emotion recognition starts.
TL;DR: In this article, (4S)-(+)-ascochin (1a) and (S, S)-(+)-ascodiketone (3) were isolated from cultures of the endophytic fungus Ascochyta sp.
13 Jun 2007
TL;DR: This paper presents a first approach for a haptic human-machine interface combined with a novel lane-keeping and collision-avoidance assistance system approach, as well as the results of a first exploration study with human test drivers.
Abstract: This paper presents a first approach for a haptic human-machine interface combined with a novel lane-keeping and collision-avoidance assistance system approach, as well as the results of a first exploration study with human test drivers. The assistance system approach is based on a potential field predictive path planning algorithm that incorporates the drivers wishes commanded by the steering wheel angle, the brake pedal or throttle, and the intended maneuver. For the design of the haptic human-machine interface the assistance torque characteristic at the handwheel is shaped and the path planning parameters are held constant. In the exploration, both driving data as well as questionnaires are evaluated. The results show good acceptance for the lane-keeping assistance while the collision avoidance assistance needs to be improved.
TL;DR: The determination of the absolute configuration (AC) of the new iridoid, prismatomerin, using vibrational circular dichroism (VCD) spectroscopy shows that the AC of 3 cannot be correctly determined by empirical comparison of the signs of the [alpha]D values of 3 and 1.
Abstract: A new highly cytotoxic iridoid has very recently been isolated from Prismatomeris tetrandra and shown to have the structure 3, similar to that of the iridoid oruwacin, 2. We report the determination of the absolute configuration (AC) of the new iridoid, prismatomerin, using vibrational circular dichroism (VCD) spectroscopy. The VCD spectrum of the acetate derivative of 3, 4, is analyzed using the Stephens theory of VCD and density functional theory (DFT). The AC of the naturally occurring 3 is shown to be 1R,5S,8S,9S,10S, identical to that of the naturally occurring iridoid plumericin, 1, also determined using VCD spectroscopy. The [alpha]D values of the natural products 3 and 1 are negative and positive, respectively. Since the ACs of 3 and 1 are identical, it follows that the AC of 3 cannot be correctly determined by empirical comparison of the signs of the [alpha]D values of 3 and 1.
TL;DR: This first test for preadolescents in the sport domain supports the generalizability of REM predictions over gender, self-concept domain, preadolescent ages, and the transition from primary to secondary school.
Abstract: Do preadolescent sport self-concepts influence subsequent sport performance? Longitudinal data (Grades 3, 4, and 6) for young boys and girls (N= 1,135; mean age = 9.67) were used to test reciprocal effects model (REM) predictions that sport self-concept is both a cause and a consequence of sport accomplishments. Controlling prior sport performance (performance-based measures and teacher assessments), prior sport self-concept had positive effects on subsequent sport performance in both Grade 4 and Grade 6 and for both boys and girls. Coupled with previous REM studies of adolescents in the academic domain, this first test for preadolescents in the sport domain supports the generalizability of REM predictions over gender, self-concept domain, preadolescent ages, and the transition from primary to secondary school.
TL;DR: The bis(guanidine)-stabilised zinc complexes [N1,N2-bis(1,3-dimethylimidazolidin-2-ylidene)ethane-1,2-diamine]dichloridozinc(II), [Zn(DMEG2e)Cl2] (C1), diacetato[N 1,N 2-bis (1, 3-dimethyl-methyl-idane-2,ylidenes)ethanes-1.2-Diamine]-
Abstract: The bis(guanidine)-stabilised zinc complexes [N1,N2-bis(1,3-dimethylimidazolidin-2-ylidene)ethane-1,2-diamine]dichloridozinc(II), [Zn(DMEG2e)Cl2] (C1), diacetato[N1,N2-bis(1,3-dimethylimidazolidin-2-ylidene)ethane-1,2-diamine]zinc(II),[Zn(DMEG2e)(CH3COO)2] (C2), and bis[N1,N2-bis(1,3-dimethylimidazolidin-2-ylidene)ethane-1,2-diamine]zinc(II) bis(trifluoromethanesulfonate), [Zn(DMEG2e)2](CF3SO3)2 (C3), have been synthesised and completely characterised by means of X-ray structure analysis, NMR spectroscopy and mass spectrometry These [bis(guanidine)]zinc complexes were investigated regarding their activity in the bulk polymerisation of D,L-lactide It could be shown that these compounds are able to act as initiators for lactide polymerisation, and polylactides with molecular weights (Mw) of around 18000–59000 g/mol could be obtained Variation of the reaction temperature revealed that the molecular weights decrease with increasing temperature Additionally, the correlation of the intrinsic viscosity with the molecular weight demonstrates that the obtained polymers are linear and structurally homogeneous(© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2007)