Volume 6
Worldwide Scientists
Young Scientists
New Books
Normal and Abnormal Circadian Characterisitics in Autonomic Cardiac Control: New Opportunities for Cardiac Risk Prevention
Functional State Approach to Fermentation Processes Modelling
Forthcoming Events
Second call for the 20th Anniversary International Symposium "Bioprocess Systems 2007 - BioPS'07"
About us
Carl Djerassi
Uldis Viesturs
Modelling and Optimization of Biotechnological Systems
Dynamical Modelling of a Wastewater Treatment Process of the Metallurgical Industry1-9
Frédéric Sauvage, David Warichet, Denis Dochain
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In this paper we consider the dynamical modelling and parameter identification of a biological wastewater treatment process from the galvanisation industry used to remove a mixture of organic matter and surface-active agents. In the present study we have considered mainly the measurements of dissolved oxygen and COD (Chemical Oxygen Demand) collected on laboratory and pilot-scale processes. From the identification study, we can conclude that the degradation is characterized by two reactions: one part of the easily biodegradable effluent is degraded with fast kinetics while the remaining part of the effluent is degraded via a slower reaction. This has been modelled by considering two different classes of substrates that indeed correspond to real components of the mixture.
Functional State Metabolism in E. coli Fed-batch Cultivation Processes10-16
Olympia Roeva, Kalin Kosev, Stoyan Tzonkov
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This paper presents an overview of a biochemical correspondence to defined functional state based on specific metabolic mechanisms. For E. coli fed-batch cultivation processes a set of functional states is considered. As a result through proposed functional states the changes in metabolic pathways can be described accurately.
One Approach for Dynamic L-lysine Modelling of Repeated Fed-batch Fermentation17-26
Tzanko Georgiev, Kalin Todorov, Ignat Dimov, Velichka Ivanova, Juliy Kristeva, Alexander Ratkov
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This article deals with establishment of dynamic unstructured model of variable volume fed-batch fermentation process with intensive droppings for L-lysine production. The presented approach of the investigation includes the following main procedures: description of the process by generalized stoichiometric equations; preliminary data processing and calculation of specific rates for main kinetic variables; identification of the specific rates as a second-order non-linear dynamic models; establishment and optimisation of dynamic model of the process; simulation researches. MATLAB is used as a research environment.
Biomedical Systems
Assessment of the Performance of the Adaptive Thresholding Algorithm for QRS Detection with the Use of AHA Database27-37
Ivaylo Christov
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Two modifications of an adaptive thresholding algorithm for heart beat detection have already been developed. The threshold combines three parameters: an adaptive slewrate value, a second value which rises when high-frequency noise occurs, and a third one intended to avoid missing of low amplitude beats. The current study assesses the performance of a new modification of the combined adaptive thresholding method for heart beat detection with the use of AHA database. The results are: Mod. 1 Se=99.58%, Sp=99.83 %; Mod. 2 Se=99.73%, Sp=99.83%; Mod. 3 Se=99.78%, Sp=99.85%. The statistical indices are higher than, or comparable to those, cited in the scientific literature.
An Automatic Statistical Method to detect the Breast Border in a Mammogram38-48
Yee Hung Choy, Wai Tak (Arthur) Hung, Robert Mitche, Xian Zhou
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Segmentation is an image processing technique to divide an image into several meaningful objects. Edge enhancement and border detection are important components of image segmentation. A mammogram is a soft x-ray of a woman's breast, which is read by radiologists to detect breast cancer. Recently, digital mammography is also available. In order to do computer aided detection on mammogram, the image has to be either in digital form or digitized. A preprocessing step to a digital/digitized mammogram is to detect the breast border so as to minimize the area to search for breast lesion. An enclosed curve is used to define the breast area. In this paper we propose a modified measure of class separability and used it to select the best segmentation result objectively, which leads to an improved border detection method. This new method is then used to analyze a test set of 35 mammograms. The breast border of these 35 mammograms was also traced manually twice to test for their repeatability using Hung's method1. The borders obtained from the proposed automatic border detection method are shown to be of better quality than the corresponding ones traced manually.
Etiological Agents of Health-care associated Surgical Site Infections49-53
Aija Žileviča, Rita Treimane, Uldis Viesturs
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Surgical site infection is the second most common nosocomial (health-care associated) infection among hospitalized patients and is a significant public health problem worldwide. Infections caused by multiresistant microorganisms are of special concern because of difficulties to treat them. From 1484 clinical samples, we isolated 1117 cultures of different gram-positive and gram-negative microorganisms. The leading agents were S. aureus and coagulase-negative Staphylococci. Methicillin resistance among S. aureus was low, while it exceeded 50% in CoNS. From gram-negative bacteria, representatives of the family Enterobacteraceae and non-fermenting rods were isolated in similar amounts. ESBL producers among E. coli and K. pneumoniae were not registered.
A Multivariate Analysis of Risk Factors for Diabetic Nephropathy54-63
Yee Hung Choy, Anthony Shannon
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& sexes and it has an association with proteinuria in female patients in the sample.' | ../../build/cleanup.shThis paper uses multivariate methods on actual data from 267 patients with noninsulin- dependent (Type 2) diabetes mellitus in order to see how the various risk factors can affect the progression of diabetic nephropathy. The approach succeeds in identifying preliminary risk factors such as smoking for males, although the females had higher fasting blood glucose at diagnosis. Not surprisingly, hypertension is common among patients of both sexes and it has an association with proteinuria in female patients in the sample.
Parameter Optimization of Multi-Element Synthetic Aperture Imaging Systems64-77
Vera Behar
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In conventional ultrasound imaging systems with phased arrays, the further improvement of lateral resolution requires enlarging of the number of array elements that in turn increases both, the complexity and the cost, of imaging systems. Multi-element synthetic aperture focusing (MSAF) systems are a very good alternative to conventional systems with phased arrays. The benefit of the synthetic aperture is in reduction of the system complexity, cost and acquisition time. In a MSAF system considered in the paper, a group of elements transmit and receive signals simultaneously, and the transmit beam is defocused to emulate a single element response. The echo received at each element of a receive sub-aperture is recorded in the computer memory. The process of transmission/reception is repeated for all positions of a transmit sub-aperture. All the data recordings associated with each corresponding pair "transmit-receive sub-aperture" are then focused synthetically producing a low-resolution image. The final high-resolution image is formed by summing of the all low-resolution images associated with transmit/receive sub-apertures. A problem of parameter optimization of a MSAF system is considered in this paper. The quality of imaging (lateral resolution and contrast) is expressed in terms of the beam characteristics - beam width and side lobe level. The comparison between the MSAF system described in the paper and an equivalent conventional phased array system shows that the MSAF system acquires images of equivalent quality much faster using only a small part of the power per image.
Sources of Variation in the QT Readings: What should you be Aware of?78-91
Iana Simova, Ivaylo Christov
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The QT interval is measured manually or automatically. In comparison with manual methods, the automated ones offer advantages in terms of absolute repeatability of measurements, immunity from errors related to observer fatigue, lack of attention, as well as efficiency and cost effectiveness that permits either more extensive and rigorous testing for the same cost as manual methods, or more rapid testing at lower cost. But a question arises: 'Can the QT interval be measured by fully automated methods with accuracy acceptable for clinical evaluations?' We created a dataset of manually measured Q-onsets and T-ends for the PTB Diagnostic ECG Database. Further on we developed a fully automated method for QT measurements and forwarded it to PhysioNet/Computers in Cardiology Challenge, 2006. The manually measured dataset was then used as a 'gold standard' for assessment of the accuracy of the automated method. The current lecture notes summarize all our up to date publications on the QT measurements topic. Sources of variation in the QT readings are for the first time discussed by the authors.
On an Intuitionistic Fuzzy Approach for Decision Making in Medicine: Part 192-101
Ludmila Todorova, Krassimir Atanassov, Stefan Hadjitodorov, Peter Vassilev
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Determining the readiness of the patient for weaning from long-term mechanical ventilation is one of the main tasks that need to be overcome by clinician in the intensive care units. In the present paper it is defined as a pattern recognition problem and four classification methods are applied in order to solve it: Stepwise discriminant analysis (SDA), stepwise logistic regression (SLR); intuitionistic fuzzy Voronoi diagrams and nonpulmonary weaning index (NPWI), applied to 17 features (variables). The result of each method is represented by relative recognition accuracy. As a final estimate of the classification a value which is received as an aggregated result from the four estimates received by each of the procedures.

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