bluuebunny/crossref_metadata_2025_split huggingface dataset:
On modelling nonlinear microwave power amplifiers in multi‐carrier transmission systems
Authors: Ermolova Natalia , Vainikainen Pertti 
Published: February 2004

AbstractA nonlinear model of the power amplifier in a multi‐carrier transmission system is discussed. It is emphasized that when the amplifier is driven by a signal with a large dynamic range, the third‐order model of its nonlinearity may be invalid. Taking into account high order components of the nonlinear model is especially important if the power amplifier produces phase distortions. A technique for an accurate prediction of the output spectrum of a nonlinear power amplifier in a multi‐carrier transmission system is presented. It is based on the fifth‐order Taylor series expansion of the complex gain of the power amplifier. The obtained formulas are simple and convenient to use. They can be employed as a basis for both design and analysis of microwave amplifiers. Copyright © 2004 AEI
A low‐complexity speech‐pause detection algorithm for communication in noisy environments
Authors: Beritelli Francesco , Casale Salvatore , Serrano Salvatore 
Published: February 2004

AbstractThe paper presents a new low‐complexity algorithm for silence suppression in adverse acoustic environments. The algorithm uses a single time‐domain input parameter (signal power) given to a simple matching block. The decision module adapts a series of thresholds depending on the current estimated signal‐to‐noise‐ratio (SNR) of the signal. A series of tests carried out using a large speech database confirm a 10% improvement in pause detection performance as compared with the AMR VAD option 1 recently adopted by ETSI for 3rd‐generation mobile systems. Copyright © 2004 AEI
Electrophysiological properties of retinal Müller glial cells from myelin mutant rat
Authors: Chávez Andrés E. , Pannicke Thomas , Roncagliolo Manuel , Reichenbach Andreas , Palacios Adrián G. 
Published: February 2004

AbstractThe structural and functional similarities between Müller cells and oligodendrocytes prompted the present study of the electrophysiological properties of Müller (glia) cells obtained from the retinae of control and myelin mutant taiep rats during the postnatal developmental period (P12–P180). The whole‐cell configuration of the patch‐clamp technique was used to characterize the general properties and the K+ currents from dissociated Müller cells. During the first 3 weeks of life, a decrease of the membrane resistance and an increase of the membrane potential were observed in Müller cells from both control and taiep rats. However, Müller cells from taiep rats never achieved the very negative membrane potential (−50 mV vs −80 mV) and the low membrane resistance characteristic for control cells. Furthermore, Müller cells displayed increased inward and outward K+ currents during postnatal development up to P30/60 in controls; however, in taiep rats, this increase ceased at P20/30, and low‐amplitude currents persisted into adulthood. These results provide first evidence of physiological changes in retinal Müller cells as a consequence of a myelin mutation causing a progressive deterioration of the central nervous system (CNS) due to a disturbance of the microtubule network of oligodendrocytes. We hypothesize that the progressive dysmyelination process of the optic nerve, accompanied by functional deficits of retinal neurons (e.g., ganglion cells), induces physiological alterations of Müller cells. © 2003 Wiley‐Liss, Inc.
The 36K protein of zebrafish CNS myelin is a short‐chain dehydrogenase
Authors: Morris Jacqueline K. , Willard Belinda B. , Yin Xinghua , Jeserich Gunnar , Kinter Michael , Trapp Bruce D. 
Published: February 2004

AbstractPrevious studies identified homologues to mammalian myelin genes expressed in the teleost central nervous system (CNS), including myelin basic protein (MBP), protein zero (P0), and a member of the proteolipid protein family, DM20. In addition, an uncharacterized 36‐kDa (36K) protein is a major component of teleost myelin, but is not a major component of myelin in other species. In the present study, we sought to better understand myelin proteins and myelination in one teleost, zebrafish, by molecular characterization of the zebrafish 36K protein. Purified zebrafish CNS myelin was isolated and the amino acid sequences of peptides present in the 36‐kDa band were determined by mass spectrometry. These sequences matched a previously uncharacterized EST in The Institute for Genome Research (TIGR) zebrafish database that is related to the short‐chain dehydrogenase/reductase (SDR) protein family. In vitro expression of the zebrafish 36K cDNA in Neuro 2a cells resulted in a protein product that was recognized by a 36K polyclonal antibody. The zebrafish 36K mRNA and protein expression patterns were determined and correlated to other known myelin gene expression profiles. In addition, we determined by in situ hybridization that a human 36K homologue (FLJ13639) is expressed in oligodendrocytes and neurons in the adult human cortex. This study identified a major myelin protein in zebrafish, 36K, as a member of the SDR superfamily; an expression pattern similar to other myelin genes was demonstrated. © 2003 Wiley‐Liss, Inc.
High‐Throughput Experimentation in Organic Coating and Thin Film Research: State‐of‐the‐Art and Future Perspectives
Authors: Schmatloch Stefan , Bach Hermann , van Benthem Rolf A. T. M. , Schubert Ulrich S. 
Published: February 2004

AbstractSummary: The success of automated and parallel drug‐discovery workflows in pharmaceutical research has sparked similar developments in materials science. This contribution provides an overview of published high‐throughput experimentation work in the area of polymeric coatings and thin films. Methodological aspects, experimental examples, and remaining challenges are discussed.Robotic system (GE) for crosshatch application.magnified imageRobotic system (GE) for crosshatch application.
Instability and Dewetting of Conducting‐Insulating Polymer Thin‐Film Bilayers
Authors: Chattopadhyay Santanu , Meredith J. Carson 
Published: February 2004

AbstractCommunication: Combinatorial thickness‐gradient libraries are used to explore stability and dewetting in thin bilayers of polystyrene (PS) on poly(3‐octylthiophene) (P3OT) on Si. At low P3OT thicknesses (90–175 nm), P3OT screens the unfavorable van der Waals (VDW) interactions between PS and Si, and the instability onset thickness of PS is depressed from 56 to 23 nm. A dramatic and unexpected transition to a VDW‐unstable interface is discovered at P3OT thicknesses above 175 nm.A digital image of a representative bilayer library.magnified imageA digital image of a representative bilayer library.
Rapid Synthesis of Polyanhydrides by Microwave Polymerization
Authors: Vogel Brandon M. , Mallapragada Surya K. , Narasimhan Balaji 
Published: February 2004

AbstractSummary: Polyanhydrides were synthesized from aliphatic and aromatic diacids using microwave radiation without vacuum at significantly reduced reaction times when compared to conventional melt polycondensation. Reaction conditions, such as duration of polymerization, equivalents of acetic anhydride, and choice of starting species, were studied. In addition, copolymers were synthesized and monomer sequence lengths were calculated using dyad conditional probabilities. The results are in good agreement with monomer sequence lengths from conventional copolymerization.Comparison of the monomer sequence lengths in poly(CPH‐co‐SA) synthesized both conventionally and by microwave heating.magnified imageComparison of the monomer sequence lengths in poly(CPH‐co‐SA) synthesized both conventionally and by microwave heating.
Parallel Dynamic Thermomechanical Measurements of Polymer Libraries
Authors: Kossuth Mary Beth , Hajduk Damian A. , Freitag Christopher , Varni John 
Published: February 2004

AbstractSummary: A common bottleneck in combinatorial materials science occurs at the characterization stage. Here we discuss an instrument for the rapid measurement of mechanical properties of polymer libraries, which allows for 96 simultaneous measurements to be taken under a variety of conditions. For example, plateau moduli and glass transition temperatures can be measured by ramping temperature while applying a deformation at a constant amplitude and frequency, much like a conventional DMTA.magnified image
Techniques and Instrumentation for Combinatorial and High‐Throughput Polymer Research: Recent Developments
Authors: Schmatloch Stefan , Schubert Ulrich S. 
Published: February 2004

AbstractSummary: Emerging from the field of biochemistry and pharmaceutical research, combinatorial and high‐throughput synthesis and screening methodologies are rapidly being adopted in polymer and materials research. Alternative solutions to cost intensive custom‐made synthetic robot systems have become commercially available and further accelerate this field of research not just in industry, but also in an academic environment. High‐throughput analysis, materials characterization, and testing (surface energy, hardness, wettability, crystallinity etc.) are key techniques and require suitable instrumentation. Here we present a short overview of recent developments of robotic synthesizers and analytical equipment extending the review from January 2003.A picture of the Accelerator™PXT100 which allows up to forty individual reactions to be performed in parallel in various modes.magnified imageA picture of the Accelerator™PXT100 which allows up to forty individual reactions to be performed in parallel in various modes.
Combinatorial Approach to Characterizing Epoxy Curing
Authors: Eidelman Naomi , Raghavan Dharmaraj , Forster Aaron M. , Amis Eric J. , Karim Alamgir 
Published: February 2004

AbstractSummary: Three complementary techniques that probe different characteristics of curing: FTIR microspectroscopy, confocal microscopy and axisymmetric adhesion testing were used to study discrete epoxy samples cured at different temperatures and to follow curing across a continuous gradient combinatorial library. Together, these techniques provide a comprehensive picture of chemical and physical changes.FTIR microspectroscopy map of epoxy film cured on a temperature gradient. Red represents the highest and blue the lowest curing.magnified imageFTIR microspectroscopy map of epoxy film cured on a temperature gradient. Red represents the highest and blue the lowest curing.
Combinatorial Physical Vapor Deposition of π‐Conjugated Organic Thin Film Libraries
Authors: Fukumoto Hiroki , Muramatsu Yukiko , Yamamoto Takakazu , Yamaguchi Jun , Itaka Kenji , Koinuma Hideomi 
Published: February 2004

AbstractSummary: Thin film technology has been attracting much interest as a tool for making combinatorial libraries of solid state materials including organic compounds and polymers as well as their devices. Especially, physical vapor deposition is very frequently used in research and development of semiconductors, metals, and advanced ceramics and its coupling with combinatorial chemical concepts has been making remarkable progress and success in recent years. Here we provide a short overview of recent studies on combinatorial fabrication of organic thin film libraries by physical vapor deposition for optimization of their structure and properties for device application.magnified image
Combinatorial Exploration of Polymeric Transport Agents for Targeted Delivery of Bioactives to Human Tissues
Authors: Petro Miroslav , Nguyen Son Hoai , Liu Mingjun , Kolosov Oleg 
Published: February 2004

AbstractSummary: Recently, in material science domain, combinatorial approaches in design, construction and screening of novel compounds and formulations have led to a significant acceleration of discovery and development. The versatility of polymeric materials offers a great opportunity to dial‐in a desired set of performance features via a proper combination of various building blocks such as monomer units or polymer chain segments. Further enhancement comes from the formulation of the polymer into its final environment in a combinatorial way. Within the last few years, a variety of parallel polymerization, purification and formulation techniques, supported by rapid automated analyses in combination with a suite of high‐throughput protocols for application‐related benefit screening, were developed and successfully applied in different fields of industry. At Symyx Technologies Inc., we have integrated a variety of synthesis, screening and information tools and procedures into robust workflows, targeting discovery and development of novel polymeric materials. In addition to the performance features of the polymeric materials, controlled by their chemical, physical and mechanical properties, we can monitor interactions of polymers with a variety of molecules and substrate surfaces. That allows us to extend the applicability of the combinatorial approach towards the macromolecular delivery agents with a wide range of use in personal care, biotech and pharma areas. The current paper reports on a generic workflow developed and applied for identification of selective transport agents for targeted delivery of bioactives to human tissues.Hit selection using screening data on polymer substantivity to substrates representing the tissue‐1 as object of preferred delivery (left) and the competitive tissue‐2 (right).magnified imageHit selection using screening data on polymer substantivity to substrates representing the tissue‐1 as object of preferred delivery (left) and the competitive tissue‐2 (right).
High‐Throughput Automated Parallel Evaluation of Zinc‐Based Catalysts for the Copolymerization of CHO and CO2 to Polycarbonates
Authors: van Meerendonk Wouter J. , Duchateau Robbert , Koning Cor E. , Gruter Gert‐Jan M. 
Published: February 2004

AbstractSummary: Copolymerization of CO2 and oxiranes using high‐pressure autoclaves typically allows one experiment per reactor per day. As a high‐throughput approach for this chemistry would be extremely valuable, a parallel setup has been validated for the copolymerization of CO2 and cyclohexene oxide (CHO) with two β‐diiminato zinc complexes. Molecular weights, polydispersities and activities were found to be comparable with literature values.Polycarbonate from cyclohexene oxide (CHO) and CO2.magnified imagePolycarbonate from cyclohexene oxide (CHO) and CO2.
Natural orbital functional approach: Calculation of dielectric properties in molecules
Authors: Piris Mario , Martinez Alberto , Otto Peter 
Published: February 2004

AbstractRecently, we proposed a new natural orbital functional for taking into account the electronic correlation in molecular systems. Calculation of dipole moments and polarizabilities of eight selected molecules are presented. By comparison with other correlated methods, it is shown that the method has predictive capabilities for these properties. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Evaluation of two‐center, three‐ and four‐electron integrals over Slater‐type orbitals in elliptical coordinates
Authors: Budziński Jan 
Published: February 2004

AbstractAn algorithm for evaluation of two‐center, three‐electron integrals with the correlation factors of the type rr and rrr as well as four‐electron integrals with the correlation factors rrr and rrr in the Slater basis is presented. This problem has been solved here in elliptical coordinates, using the generalized and modified form of the Neumann expansion of the interelectronic distance function r for k ≥ −1. Some numerical results are also included. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Critical evaluation of a high‐throughput analytical method for polychlorinated biphenyls in human serum: which detector for the establishment of the reference values?
Authors: Turci Roberta , Mariani Giulio , Marinaccio Alessandro , Balducci Claudio , Bettinelli Maurizio , Fanelli Roberto , Nichetti Simona , Minoia Claudio 
Published: February 2004

AbstractA rapid screening method, previously developed and validated for the determination of 60 PCB congeners in human serum by using high‐resolution gas chromatography coupled with low‐resolution mass spectrometry, was applied to the establishment of the reference values in the general population. The reliability of this method was further confirmed by analyzing ten serum samples, obtained from the same population group involved in the original study, by electron impact ionization with either low‐ or high‐resolution mass spectrometry. Analyses in electron capture negative ionization mode were also performed for the determination of ‘dioxin‐like’ isomers. The data were found to be in good accordance with one another, especially for the congeners of highest environmental significance. Then, 162 real serum samples were analyzed for the presence of PCBs. Comparison with the results from other studies reported in the literature showed that a similar profile was observed; the most abundant congeners were #153, #180, #138 and #170. A statistical analysis was performed to determine whether there were significant correlations between PCB concentrations and specific variables such as age, gender, and dietary habits. Copyright © 2004 John Wiley & Sons, Ltd.
Neurotrophins and extracellular matrix molecules modulate sensory axon outgrowth
Authors: Hari Ashwinii , Djohar Baharak , Skutella Thomas , Montazeri Sonia 
Published: February 2004

AbstractNeurotrophins have been known to play a pivotal role in axonal guidance. Recent research has implicated the role of extracelluar matrix molecules in co‐ordinating axonal movement. In this study, we examined the influence of neurotrophins (nerve growth factor (NGF) and neurotrophin‐3 (NT‐3)) and extracellular matrix molecules (laminin, fibronectin, and poly‐l‐lysin) on sensory neurite outgrowth in thoracic dorsal root ganglia (DRG) dissected from rats at embryonic day 13. Adjacent DRG were embedded in a collagen gel matrix and supplemented with NGF or NT‐3. Under NT‐3 conditions, DRG axons extended towards each other and intermingled, while neurites from NGF‐treated DRG demonstrated a strong repellent effect, resulting in turning responses and growth cone collapse. This effect was not observed on a collagen culture surface. Interestingly, the composition of the extracellular matrix strongly influenced the observed repellent effect. Sensory neurites from NGF‐stimulated DRG again demonstrated a repellent effect when plated on a laminin surface, but showed intermingling behavior when plated on poly‐l‐lysin or fibronectin. This observation suggests that a factor secreted by NGF‐treated DRG axons interacts with laminin, enabling repulsion. This factor and its interaction with the extracellular matrix play an important role in the mechanism of sensory axonal pathfinding.
The impact of feral horses on grassland bird communities in Argentina
Authors: Zalba Sergio M. , Cozzani Natalia C. 
Published: February 2004

AbstractThe impact of introduced herbivores on the composition and structure of plant communities has been widely studied. However, little is known about how they affect wildlife. We studied the impact of feral horses under different grazing regimes on the communities of birds in a nature reserve in the Pampas grasslands in Argentina. The areas that had predominantly tall grass (enclosures and areas of moderate grazing intensity) showed the greatest species richness and total abundance of birds. Some species, e.g. the southern lapwing (Vanellus chilensis), were associated with the presence of horses, while others, e.g. pipits (Anthus spp), were more common in lesser grazed areas. The presence of feral horses was associated with an increase in the rate of predation of eggs which varied from 12.5% within the enclosures to 70% in grazed areas. It is suggested that the increase in predation rate was due to the increased visibility of the nests and an increase in the density of opportunist carnivores. Small areas of grassland in a good state of conservation could serve as sources that would maintain communities of birds in the more transformed sections.
Strategic planning for captive populations: projecting changes in genetic diversity
Authors: Earnhardt Joanne M. , Thompson Steven D. , Schad Kristine 
Published: February 2004

AbstractMaintenance of genetic diversity is critical for the preservation of small populations. Most captive populations are small and managers focus their efforts on reducing extinction risks by minimising loss of genetic diversity. To project changes in genetic diversity, managers use a genetic drift model. We used data from 40 managed captive populations to test whether this drift model is a good predictor of change in genetic diversity by comparing projected 10‐year trajectories of annual loss in expected heterozygosity with the changes estimated from pedigree analysis. We found that the drift model frequently overestimated the rate at which genetic diversity would be lost and could not predict increases, which we observed in 22 species. We suggest that the drift model does not adequately reflect the potential for management strategies, such as prioritised breeding recommendations and recruitment of potential founders, to slow the loss of genetic diversity. In many cases, the drift model may be overly pessimistic, leading managers to seek solutions such as importation, increased population size or the abandonment of a captive population, that may be unnecessary or premature. Managers should be cautious when interpreting results from genetic drift models, taking care to assess how management actions might lead to more optimistic prognoses.
Carnivore re‐colonisation: reality, possibility and a non‐equilibrium century for grizzly bears in the southern Yellowstone ecosystem
Authors: Pyare Sanjay , Cain Steve , Moody Dave , Schwartz Chuck , Berger Joel 
Published: February 2004

AbstractMost large native carnivores have experienced range contractions due to conflicts with humans, although neither rates of spatial collapse nor expansion have been well characterised. In North America, the grizzly bear (Ursus arctos) once ranged from Mexico northward to Alaska, however its range in the continental USA has been reduced by 95–98%. Under the U. S. Endangered Species Act, the Yellowstone grizzly bear population has re‐colonised habitats outside Yellowstone National Park. We analysed historical and current records, including data on radio‐collared bears, (1) to evaluate changes in grizzly bear distribution in the southern Greater Yellowstone Ecosystem (GYE) over a 100‐year period, (2) to utilise historical rates of re‐colonisation to project future expansion trends and (3) to evaluate the reality of future expansion based on human limitations and land use. Analysis of distribution in 20‐year increments reflects range reduction from south to north (1900–1940) and expansion to the south (1940–2000). Expansion was exponential and the area occupied by grizzly bears doubled approximately every 20 years. A complementary analysis of bear occurrence in Grand Teton National Park also suggests an unprecedented period of rapid expansion during the last 20–30 years. The grizzly bear population currently has re‐occupied about 50% of the southern GYE. Based on assumptions of continued protection and ecological stasis, our model suggests total occupancy in 25 years. Alternatively, extrapolation of linear expansion rates from the period prior to protection suggests total occupancy could take >100 years. Analyses of historical trends can be useful as a restoration tool because they enable a framework and timeline to be constructed to pre‐emptively address the social challenges affecting future carnivore recovery.