bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivariate biological profiling and principal toxicity regions of compounds: the PCB case study
Authors: Eriksson Lennart , Andersson Patrik L. , Johansson Erik , Tysklind Mats 
Published: October 2002

AbstractThe chemometric QSAR strategy, as applied in environmental sciences and drug design, is based on (1) multivariate characterization of chemical structure, (2) multivariate design in the principal properties of a set of compounds to select a representative training set, and (3) multivariate modelling of the structure–activity relationships. A multivariate QSAR investigation is often commenced by applying a screening design, and the selected compounds are tested biologically in a broad battery of test systems (‘multivariate biological profiling’). In many cases the result is such that for certain biological end‐points only some of the tested compounds are active, while for another set of biological end‐points other tested chemicals are active. In other words, when looking at the chemical property space, there may be both responding and non‐responding toxicity regions, or even regions of very specific toxicity mechanisms. This may lead to loss of resolution and balance in the resulting QSAR models. Therefore it might sometimes be worthwhile to focus the QSAR modelling on parts of the chemical space where high toxicity is expected or known to be the case. In this paper we describe a multi‐stage modification of the chemometric QSAR strategy, aimed at identifying focused sets of compounds that provide a good mapping of such principal toxicity regions. This strategy is based on PCA, PLS and multivariate design in several stages. The strategy is illustrated using a data set of polychlorinated biphenyls, a set of compounds for which seven biological end‐points were determined. Copyright © 2002 John Wiley & Sons, Ltd.
Feasibility study of NIR for surveillance of a pharmaceutical process, including a study of different preprocessing techniques
Authors: Stordrange Laila , Libnau Fred Olav , Malthe‐Sørenssen Dick , Kvalheim Olav M. 
Published: October 2002

AbstractMultivariate calibration models for predicting the initial reactant and an impurity in a synthesis of contrast media have been developed using near‐infrared (NIR) spectroscopy. The reaction is presently monitored off‐line by HPLC. The calibration models are based on spectra measured on‐line. The process solution is chemically complex and the intention of this study was to enhance knowledge about the predictive ability of the models. Different data‐preprocessing and variable selection methods reported in the literature have been tested in order to enhance chemical information and reduce irrelevant variability due to physical influences on measured spectra such as scattering and temperature. In addition to standard preprocessing methods such as normalization, differentiation and multiplicative scatter correction, orthogonal signal correction and optimized scaling were tested. The modelling was performed by partial least squares (PLS), except for optimized scaling which uses principal component regression (PCR). Optimized scaling on differentiated data gave the lowest prediction error. The NIR region from 1100 to 1900 nm gave better models than variable selection and fewer variables. Models with correlation coefficients for best fit equal to 0.998 and 0.961 were obtained for the initial reactant and the impurity, respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Reconstruction of smooth distributions within unsmooth circumferences from limited views using filtered‐backprojection algorithm
Authors: Feng J. , Bao S.L. 
Published: October 2002

AbstractThis study demonstrates the feasibility of reconstruction of smooth distributions within unsmooth circumferences from limited views using the filtered‐backprojection algorithm with angular interpolation in Fourier domain, which leads to noniterative reconstruction of smooth distributions within skulls in diagnostic medicine. Two phantoms with a circular and an elliptic circumference are numerically tested. This speedy approach has great advantages in applications when swift reaction is necessary or when result of reconstruction is indispensably navigational to its following detection. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 93–96, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10015
An accelerated multiplicative iterative algorithm in image reconstruction
Authors: Liu Li , Wang Yuan‐mei 
Published: October 2002

AbstractBased on the ML‐EM (maximum likelihood expectation maximization) algorithm and AWLS (one kind of multiplicative weighted least square) reconstruction, a new algorithm named RMITC (rapid multiplicative iteration with total‐count conservation) is proposed. The new method assumes a higher order correction factor and incorporates a total‐count conservation constraint to obtain better images reconstructed while achieving a higher speed of convergence. Computer simulated phantom data and real positron emission tomography (PET) transmission data were used to compare the new method with other reconstruction algorithms, such as ML‐EM and AWLS. Results demonstrated that the new method is faster and better quantitatively than both ML‐EM and AWLS. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 97–100, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10016
Position‐dependent defocus processing for acoustic holography images
Authors: Yin Ruming , Flynn Patrick J. , Broschat Shira L. 
Published: October 2002

AbstractAcoustic holography is a transmission‐based ultrasound imaging method that uses optical image reconstruction and provides a larger field of view than pulse‐echo ultrasound imaging. A focus parameter controls the position of the focal plane along the optical axis, and the images obtained contain defocused content from objects not near the focal plane. Moreover, it is not always possible to bring all objects of interest into simultaneous focus. In this article, digital image processing techniques are presented to (1) identify a “best focused” image from a sequence of images taken with different focus settings and (2) simultaneously focus every pixel in the image through fusion of pixels from different frames in the sequence. Experiments show that the three‐dimensional image information provided by acoustic holography requires position‐dependent filtering for the enhancement step. It is found that filtering in the spatial domain is more computationally efficient than in the frequency domain. In addition, spatial domain processing gives the best performance. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 101–111, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10017
Analysis of the compatibility conditions for the radon projections, with an application to seismology
Authors: Bindi Dino , Caponnetto Andrea 
Published: October 2002

AbstractIn the context of the Radon approach to tomographic imaging, we face the problem of ascertaining whether or not a set of functions can be considered a set of reliable projections of an unknown function. We first review some results about the singular system of the Radon operator. Then, we define a set of parameters that allows us to evaluate the degree of compatibility of a set of projections. We apply our analysis to the seismic source imaging problem. In particular, we show that the compatibility conditions can be used for the empirical Green function retrieval. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 112–116, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10018
On estimation of the number of image principal colors and color reduction through self‐organized neural networks
Authors: Atsalakis A. , Papamarkos N. , Andreadis I. 
Published: October 2002

AbstractA new technique suitable for reduction of the number of colors in a color image is presented in this article. It is based on the use of the image Principal Color Components (PCC), which consist of the image color components and additional image components extracted with the use of proper spatial features. The additional spatial features are used to enhance the quality of the final image. First, the principal colors of the image and the principal colors of each PCC are extracted. Three algorithms were developed and tested for this purpose. Using Kohonen self‐organizing feature maps (SOFM) as classifiers, the principal color components of each PCC are obtained and a look‐up table, containing the principal colors of the PCC, is constructed. The final colors are extracted from the look‐up table entries through a SOFM by setting the number of output neurons equal to the number of the principal colors obtained for the original image. To speed up the entire algorithm and reduce memory requirements, a fractal scanning subsampling technique is employed. The method is independent of the color scheme; it is applicable to any type of color images and can be easily modified to accommodate any type of spatial features. Several experimental and comparative results exhibiting the performance of the proposed technique are presented. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 117–127, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10019
Robust estimation of 3D trajectories from a monocular image sequence
Authors: Pang Chung‐Yi Chan , Guesalaga Andrés R. , Roda Valentín Obac 
Published: October 2002

AbstractThis article describes a new method for object trajectory estimation that uses sequences of images taken from a monocular camera. The method integrates a Kalman filter to estimate the three‐dimensional (3D) parameters of the optical system and a lineal projective model to determine 3D point coordinates projected on the retinal plane. It works with at least three distinctive points in the image, and they are updated with correlation methods. The result is an estimation of the rotation and translation parameters between successive images within the sequence and yield to the 3D coordinates of the points selected for correspondence. The scaling problem related to 3D reconstruction is tackled via a priori information of the objects being observed. The method is tested with synthetic images to evaluate its accuracy, and later, an interesting application in autonomous navigation is presented. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 128–137, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10020
High‐Cell‐Density Fermentation of Recombinant Saccharomyces cerevisiae Using Glycerol
Authors: Raj A. Eugene , Kumar H. S. Sathish , Kumar S. Umesh , Misra M. C. , Ghildyal N. P. , Karanth N. G. 
Published: October 2002

AbstractTo obtain a high cell density of recombinant Saccharomyces cerevisiae (INVSc 1 strain bearing a 2 μm plasmid, pYES2 containing a GAL1 promoter for expression of the β‐galactosidase gene), the yeast was grown with glycerol as the substrate by fed‐batch fermentation. The feeding strategy was based on an on‐line response of the medium pH to the consumption of glycerol. The approach was to feed excess carbon into the medium to create a benign environment for rapid biomass buildup. During cell growth in the presence of glycerol, the release of protons in the medium caused a decrease in pH and the consumption rate of ammonium phosphate served as an on‐line indicator for the metabolic rate of the organism. The extent of glycerol feeding in a fed‐batch mode with pH control at 5.0 ± 0.1 was ascertained from the automatic addition of ammonium phosphate to the medium. The glycerol feeding to ammonium phosphate addition ratio was found to be 2.5–3.0. On the basis of the experiments, a maximum dry cell biomass of 140 g per liter and a productivity of 5.5 g DCW/L/h were achieved. The high cell density of S. cerevisiae obtained with good plasmid stability suggested a simple and efficient fermentation protocol for recombinant protein production.
Control of Secondary Metabolite Congener Distributions via Modulation of the Dissolved Oxygen Tension
Authors: Frykman Scott A. , Tsuruta Hiroko , Starks Courtney M. , Regentin Rika , Carney John R. , Licari Peter J. 
Published: October 2002

AbstractMany secondary metabolites, including various polyketides, require complex enzymatic pathways for modification into their final biologically active forms. Limitation of the dissolved oxygen supplied during cultivation of various microbial strains can decrease the activity of cytochrome P‐450 monooxygenases required for the processing of pathway intermediates into their final forms, resulting in the accumulation of these intermediates as the primary products. Here, a generalized oxygen‐limited cultivation strategy is specifically demonstrated with a myxobacterial strain engineered to heterologously express the epothilone polyketide synthase (PKS) gene cluster under either an excess (the dissolved oxygen tension is maintained at 50% of saturation) or a depleted (no residual dissolved oxygen detected) level of oxygenation during cultivation. Cultivation of this myxobacterial strain with excess oxygenation resulted in the production of epothilones A and B as the primary products, while cultivation of this same strain under depleted oxygenation resulted in the production of epothilones C and D as the primary products. Additionally, the peak cell density in the oxygen‐depleted cultivations was 60% higher than that observed in oxygen‐excess cultivations. Finally, an active EpoK epoxidase was found to catalyze the production of a novel epothilone (Epo506) with an unexpected structure during the cultivation of another myxobacterial strain expressing a genetically modified epothilone PKS under excess oxygenation. The structure of Epo506 was determined by high‐resolution mass spectrometry and one‐ and two‐dimensional NMR.
Bactericidal Properties of Flat Surfaces and Nanoparticles Derivatized with Alkylated Polyethylenimines
Authors: Lin Jian , Qiu Shuyi , Lewis Kim , Klibanov Alexander M. 
Published: October 2002

AbstractWe previously discovered that covalently coating glass and plastic slides with certain long poly(vinyl‐ N‐alkylpyridinium) chains enables the resultant surfaces to kill a variety of airborne and waterborne bacteria on contact. In the present study, these findings have been extended to an unrelated polymer class, polyethylenimines (PEIs). Alkylated PEIs attached to flat macroscopic surfaces and to those of nanoparticles make these materials highly bactericidal toward both Gram‐positive and Gram‐negative pathogenic bacteria. Systematic chemical modifications of the immobilized PEI conducted herein shed light on the relationship between the structure of the polymer and the antibacterial efficiency of the resultant coating.
Sustainable use of the Amazon River floodplain: Problems and possibilities
Authors: Junk Wolfgang J. 
Published: October 2002

Abstract
The Amazon River floodplain (várzea) belongs to the few areas in central Amazonia with relatively high natural fertility and productivity, because the annual flooding with sediment-rich water add nutrients to the system. Many development planners consider the area to be of high agricultural production potential and of great importance for regional and national economy and development. Inland fishery provides an important part of the animal protein supply of the local population. However, agricultural production is low and does not satisfy the demand of large cities like Manaus, because of the specific ecological conditions of the várzea. Politicians have two options directing development planning: towards a small scale diversified agriculture to satisfy local and regional market demand or towards large scale export-oriented agro-industrial development. Decision makers face the problem that, because of the flood pulse, floodplain ecosystems behave differently from other ecosystems. There is little useful information available from other regions, because most of the cost-intensive management systems of temperate zone floodplains have failed and there is little information on low-cost management systems of tropical floodplains.
Principle ecological parameters of the Amazon floodplain and a cost benefit analysis of the actual production systems are presented. Data analysis shows serious economic, social and ecological restrictions favoring small scale labor-intensive farming systems in comparison with high-technological agro-industrial solutions.
Wise use of wetlands, the Ramsar Convention on wetlands, and the need for an Asian Regional Wetlands Training Initiative
Authors: Mitchell Arthur H. 
Published: October 2002

Abstract
Proper management and protection of tropical aquatic ecosystems, or wetlands, are essential for a healthy environment and for the sustainability of resources required by a growing human population. The definition of wetlands, as accepted by the Ramsar Convention and Wetlands International is presented together with a summary of wetlands benefits. The Convention on Wetlands of International Importance is described, including the eight General Objectives of the Convention'sStrategic Plan (1997-2002), and their twenty-eight Operational Objectives, which in turn identify more than 125 specific actions. The focus of this paper is on General Objective 4 and its two Operational Objectives, which focus on training and capacity building for wetlands management by the Contracting Parties to the Convention. The Ramsar List of Wetlands of International Importance, its objectives and criteria, is discussed. A summary of wetlands training needs assessments in the Asian region is briefly covered, followed by a proposed development of a Wetlands Training Initiative for Asia. This includes the main elements of a training initiative, potential target groups of a multi-layered and multi-stakeholder training approach, and the need for a Coordination Centre for the Asian Training Initiative.
What defines a ‘healthy’ lake? Evidence from Lake Naivasha, Kenya
Authors: Hubble D.S. , Harper D.M. 
Published: October 2002

Abstract
Aquatic ecosystem health is often defined in terms of an earlier ‘preferred’ state described by earlier observations or palaeolimnology. Many tropical lakes are deteriorating, but few have a known history. Lake Naivasha (Kenya) however may be unique in having a 30000-year palaeoecological history during which it has undergone major fluctuations. It has a written history beginning in the 19th century, and has since experienced extreme changes through drought and human activity. It is now a Ramsar site, and so provides an ideal case study to examine the meaning of ‘aquatic health’. Although it has periodically dried, in its ‘natural’ state the lake supported dense submerged and fringing vegetation, much of which has now been lost. It is moderately eutrophic, has an unbalanced water budget and has experienced a number of exotic species introductions. The history of scientific work at Lake Naivasha is summarised from the earliest expedition in 1929, and with palaeolimnological evidence, is used to chart changes in the lake system including its chemistry, phytoplankton, macrophytes, macroinvertebrates and vertebrates. As the lake shows broad natural fluctuations, no single ‘natural’ state can be described. Despite anthropogenic impacts, the lake can still be considered reasonably ‘healthy’ although many of its components have been changed by human activity. Ongoing pressures on the system give cause for concern about its future condition and management.
Freshwater biodiversity: An outlook of objectives, achievements, research fields, and co-operation
Authors: Bíró Péter 
Published: October 2002

Abstract
This paper reviews the issue of freshwater biodiversity, from the time of its introduction on national and international bases. The project was initiated in co-operation by the International Union of Biological Sciences, the International Society of Limnology Working Group on Biodiversity in Freshwater Ecosystems and the Hydrobiological Committee of Hungarian Academy of Sciences. The first International Union of Biological Sciences International Workshop on Freshwater Biodiversity was convened at Balatonfüred, Hungary during 25-28 August 1996. A framework was developed and a wide scale project, BIODIVERSITAS, was worked out by Prof. Hiroya Kawanabe and Dr. Christian Lévesque. This project became one of the main issues of the International Union and has been incorporated into the activities of the United Nations Educational, Scientific and Cultural Organization. Several national and international meetings have been held dealing with particular fields in relation to species richness of aquatic ecosystems so that the topic has became a broad scientific, social, popular, political and economic issue. Scientific questions already cover nearly all aspects of biodiversity, for example, how to measure indices, and how to manage and preserve species richness in the most endangered aquatic habitats. Inventorying, monitoring and conservation of biodiversity in freshwater are of vital importance. All freshwater plant and animal species (invertebrates and vertebrates) are more or less threatened by human activities. Any decrease in diversity of aquatic species may indicate harmful human impacts, and whenever these activities increase, the living world of rivers, lakes and reservoirs is degraded. The rehabilitation of degraded aquatic systems has been a major limnological issue all over the world.
Freshwater biodiversity is studied in all types of habitats: lakes, reservoirs, rivers and wetlands and includes species from bacteria to aquatic vertebrates, and focuses on functional aspects and habitat differences (lake shores/ecotones, open waters and benthic habitats). Research on freshwater biodiversity can best be organized according to selected water bodies on different continents.
The ‘status quo’ of freshwater stocks is of crucial importance on local, regional and global scales. A crucial point is the high-level training of specialists and improving public-relations in order to make communities understand all aspects concerning ecological crises (e.g., habitat and biodiversity erosion and their consequences on nature and human beings). However, special interest must also be afforded to soil and sediment biodiversity, microbial biodiversity, human dimensions and genetic diversity in both land and aquatic systems.