Volume 10
Worldwide Scientist
Martins Bekers, Prof., D. Sc., Full Member of Latvian Academy of Sciences
Mincho Bankov Hadjiski, Prof., D.Sc., Corresponding Member of Bulgarian Academy of Sciences
New Books
Our Sponsor: Ecopharm
Dynamics and Complexity in a Time Delay Model of RNA Silencing with Periodic Forcing1-12
Svetoslav Nikolov
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Simple periodic behavior and occurrence of complex oscillatory phenomena underlie of a large number of biochemical system models. In many cases the transition from stable to simple/complex oscillatory behavior can be connected with the appearance of abnormal process likes as cancer. In this paper we propose a time delay model of RNA silencing (also known as RNA interference) with periodic forcing. In organisms with RNA silencing, each cell has a miniature "immune system" able to generate and amplify specific responses to a variety of gene transcripts. The consequences of a time delay on the dynamics of this model are analysed using Hopf's theorem. Our analytical calculations predict that time delay acts as a key bifurcation parameter. From the accomplished numerical results, it becomes clear that model has complexity oscillatory behavior when the amplitude of periodic force (i.e. the confusion in the target mRNA synthesis) is large.
Bioprocess Systems
The Self-regulation of Metabolism, taking into Account the Optimal Regulation and the Energetics of the Processes13-20
Mikhail Matveev
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In this study the metabolic network of cell energetics are investigated as a self-regulating system, the control which is described with non-classical variation method - the Bellman's equation (also known as a dynamic programming equation), on the basis of the thermodynamics of irreversible processes and the kinetics of the biochemical reactions.
Multiple Objective Optimization and Optimal Control of Fermentation Processes21-30
Mitko Petrov
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A multiple objective optimization is applied for finding an optimum policy of fed-batch processes of whey fermentation and L-lysine production. The multiple objective optimization problems are transformed to a standard problem of optimization with single objective function by a general utility function with weight coefficients for each single utility coefficient criteria. A combined algorithm is applied when solving the maximizing decision problem. The algorithm includes a method for random search of finding an initial point and a method based on the fuzzy sets theory, combined in order to find the best solution of the optimization problem. The application of the combined algorithm eliminates the main disadvantage of the used fuzzy optimization method, namely it decreases the number of discrete values of the control variables. Thus, the algorithm allows problems with larger scale to be solved. After this multiple optimization, the useful product quality rises and the residual substrate concentration at the end of the process decreases. In this way, the process productivity is increased.
Two Approaches to Control of Fed-batch Fermentation Process31-40
Tatiana Ilkova
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L-lysine is one of the irreplaceable aminoacids whose content in the animal protein is relatively high in comparison to plants, where the content is relatively low. The insufficiently L-lysine quantity in the fodders reduces the biological value of the fodder doses, reduces the weight increase and the further productiveness of the agricultural animals, it increases the fodder quantity, used for a kilogram growth and decreases the product quantity of animal origin. The most effective and cheapest method for the L-lysine biosynthesis (in biological active form) is the microbiological method via a direct fermentation. In this paper it is used an optimization method at the L-lysine production from strain Brevibacterium flavum 22LD - Neuro-dynamic programming. For receiving a feedback and robustness of the optimal control profile the Model predictive control of the L-lysine production is developed.
Generalized Nets as Tools for Modelling of Biological and Medical Processes41-58
Krassimir T. Atanassov
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Short remarks on Generalized Net (GN) theory are given. Some applications of GNs in biology and medicine are discussed.
Biomedical Systems
Assessment of the Efficacy of Pulsed Biphasic Defibrillation Shocks for Treatment of Out-of-hospital Cardiac Arrest59-70
Irena Jekova, Jean-Philippe Didon, Vessela Krasteva, Guy Fontaine, Manuel Contini, Johann-Jakob Schmid
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This study evaluates the efficacy of a Pulsed Biphasic Waveform (PBW) for treatment of out-of-hospital cardiac arrest (OHCA) patients in ventricular fibrillation (VF). Large database (2001-2006), collected with automated external defibrillators (AED), (FRED?®, Schiller Medical SAS, France), is processed.
In Study1 we compared the defibrillation efficacy of two energy stacks (90-130-180 J) vs. (130-130-180 J) in 248 OHCA VF patients. The analysis of the first shock PBW efficacy proves that energies as low as 90 J are able to terminate VF in a large proportion of OHCA patients (77% at 5 s and 69% at 30 s). Although the results show a trend towards the benefit of higher energy PBW with 130 J (86% at 5 s, 73% at 30 s), the difference in shock efficacy does not reach statistical significance. Both PBW energy stacks (90-130-180 J) and (130-130-180 J) achieve equal success rates of defibrillation. Analysis of the post-shock rhythm after the first shock is also provided.
For Study2 of 21 patients with PBW shocks (130-130-180 J), we assessed some attending OHCA circumstances: call-to-shock delay (median 16min, range 11-41 min), phone advices of CPR (67%). About 50% of the patients were admitted alive to hospital, and 19% were discharged from hospital. After the first shock, patients admitted to hospital are more often presenting organized rhythm (OR) (27% to 55%) than patients not admitted (0% to 10%), with significant difference at 15 s and 30 s. Post-shock VFs appear significantly rare until 15s for patients admitted to hospital (0% to 9%) than for patients not admitted to hospital (40% to 50%). Return of OR (ROOR) and efficacy to defibrillate VF at 5 s and 15 s with first shock are important markers to predict patient admission to hospital.
Screening for Gestational Diabetes Mellitus: Is it Effective?71-74
Anthony Shannon
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The purpose of the studies reported here was to examine the problem of the effectiveness of screening for gestational diabetes mellitus. It utilises meta-analysis to examine the conclusions of many studies in order to come up with a practical solution to the problem.
Meta-analysis of the Effect of Medication on Falls in the Elderly75-87
Anthony G. Shannon, Daniel K. Y. Chan, Wai Tak Hung, Yee Hung Choy
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The objective of this study was to carry out a systematic quality review and meta-analysis of all literature published in years 1981-1997 which studied the effect of drugs in the elderly and which had analyzable data on major groups of drugs. The sources of data were reports of surveys, case-control, prospective and retrospective studies, published in English. Identified studies were assessed for (i) ecological, (ii) methodological and (iii) statistical features. The drugs were classified into four main groups, namely (a) antidepressants (b) antipsychotics, (c) diuretics, and (d) hypnosedatives. Increasing risk of falls were related in order to diuretics, hypnosedatives, antidepressants and antipsychotics: the odd ratios with antipsychotics was 42% higher than with diuretics. The conclusion was that, clinically, the following classes of drugs show a significant positive relationship with falls: antipsychotics, antidepressants and hypnosedatives. The relationship with diuretics and falls is less clear; at best, it has a weak relationship with falls.
Power-line Interference Removal from ECG in Case of Power-line Frequency Variations88-96
Ivan Dotsinsky, Todor Stoyanov
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The original version of the most successful approach for power-line (PL) interference removal from ECG, called subtraction procedure, is based on linear segment detection in the signal and hardware synchronised analogue-to-digital conversion to cope with the PL frequency variations. However, this is not feasible for battery supplied devices and some computer-aided ECG systems. Recent improvements of the procedure apply software measurement of the frequency variations that allow a re-sampling of the contaminated signal with the rated PL frequency followed by interference removal and back re-sampling for restoration of the original time intervals. This study deals with a more accurate software frequency measurement and introduces a notch filtration as alternative to the procedure when no linear segments are encountered for long time, e.g. in cases of ventricular fibrillation or tachycardia. The result obtained with large PL frequency variations demonstrate very small errors, usually in the range of ± 20 ?V for the subtraction procedure and ± 60 ?V for the notch filtration, the last values strongly depending on the frequency contents of the QRS complexes.
Ecological Systems
Regional Persistent Organic Pollutants' Environmental Impact Assessment and Control Model97-105
Jurgis Staniskis, Romanas Cesnaitis
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The sources of formation, environmental distribution and fate of persistent organic pollutants (POPs) are increasingly seen as topics to be addressed and solved at the global scale. Therefore, there are already two international agreements concerning persistent organic pollutants: the Protocol of 1998 to the 1979 Convention on the Long-Range Transboundary Air Pollution on Persistent Organic Pollutants (Aarhus Protocol); and the Stockholm Convention on Persistent Organic Pollutants. For the assessment of environmental pollution of POPs, for the risk assessment, for the evaluation of new pollutants as potential candidates to be included in the POPs list of the Stokholmo or/and Aarhus Protocol, a set of different models are developed or under development. Multimedia models help describe and understand environmental processes leading to global contamination through POPs and actual risk to the environment and human health. However, there is a lack of the tools based on a systematic and integrated approach to POPs management difficulties in the region.

© 2008, BAS, Institute of Biophysics and Biomedical Engineering