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排序方式: 共有267条查询结果,搜索用时 15 毫秒
1.
Panos M. Pardalos Wanpracha Chaovalitwongse Leonidas D. Iasemidis J. Chris Sackellares Deng-Shan Shiau Paul R. Carney Oleg A. Prokopyev Vitaliy A. Yatsenko 《Mathematical Programming》2004,101(2):365-385
There is growing evidence that temporal lobe seizures are preceded by a preictal transition, characterized by a gradual dynamical change from asymptomatic interictal state to seizure. We herein report the first prospective analysis of the online automated algorithm for detecting the preictal transition in ongoing EEG signals. Such, the algorithm constitutes a seizure warning system. The algorithm estimates STLmax, a measure of the order or disorder of the signal, of EEG signals recorded from individual electrode sites. The optimization techniques were employed to select critical brain electrode sites that exhibit the preictal transition for the warning of epileptic seizures. Specifically, a quadratically constrained quadratic 0-1 programming problem is formulated to identify critical electrode sites. The automated seizure warning algorithm was tested in continuous, long-term EEG recordings obtained from 5 patients with temporal lobe epilepsy. For individual patient, we use the first half of seizures to train the parameter settings, which is evaluated by ROC (Receiver Operating Characteristic) curve analysis. With the best parameter setting, the algorithm applied to all cases predicted an average of 91.7% of seizures with an average false prediction rate of 0.196 per hour. These results indicate that it may be possible to develop automated seizure warning devices for diagnostic and therapeutic purposes.Mathematics Subject Classification (1991):20E28, 20G40, 20C20 相似文献
2.
3.
Wanpracha Art Chaovalitwongse Oleg A. Prokopyev Panos M. Pardalos 《Annals of Operations Research》2006,148(1):227-250
Epilepsy is among the most common brain disorders. Approximately 25–30% of epilepsy patients remain unresponsive to anti-epileptic
drug treatment, which is the standard therapy for epilepsy. In this study, we apply optimization-based data mining techniques
to classify the brain's normal and epilepsy activity using intracranial electroencephalogram (EEG), which is a tool for evaluating
the physiological state of the brain. A statistical cross validation and support vector machines were implemented to classify
the brain's normal and abnormal activities. The results of this study indicate that it may be possible to design and develop
efficient seizure warning algorithms for diagnostic and therapeutic purposes.
Research was partially supported by the Rutgers Research Council grant-202018, the NSF grants DBI-980821, CCF-0546574, IIS-0611998,
and NIH grant R01-NS-39687-01A1. 相似文献
4.
Panos Nikitas 《The Chemical Educator》2002,7(2):61-65
Plancks work on the Second Law of Thermodynamics in combination with a simple thermodynamic approach developed by Blinder show that the concept of entropy is introduced from the First and not the Second Law of Thermodynamics. In particular, it is proved that the First Law of Thermodynamics leads directly to the following statement: For every system of whatever complexity there exists an extensive function of state S defined from dS = qrev/T, where qrev is the infinitesimal quantity of heat exchanged reversibly between the system and the surroundings and T is the absolute temperature of the system. Thus, for reversible adiabatic processes we readily have from the First Law that dS = 0. Therefore, the Second Law should be properly reformulated, restricted to the inequality dS 0 for irreversible processes only. 相似文献
5.
George V. Rekatas Vassilis J. Demopoulos Panos N. Kourounakis 《Journal of heterocyclic chemistry》1996,33(3):989-990
In this work, the synthesis of 1-(pyridine-3-carbonyl)pyrrolidin-2-one ( 1a ) and 1-(2-propyl-1-pentanoyl)pyrrolidin-2-one ( 1b ) by cyclization of the corresponding GABA derivatives, is reported. Two different methods are developed. For the synthesis of 1a , the parent molecule 4-[(pyridine-3-carbonyl)-amino]butanoic acid ( 2a ) is treated first with thionyl chloride and then with triethylamine. The second derivative, 1b , is produced by an intramolecular dehydration of 4-(2-propylpentanoylamino)butanoic acid ( 2b ) using an acid catalyst. 相似文献
6.
Hatsis P Brombacher S Corr J Kovarik P Volmer DA 《Rapid communications in mass spectrometry : RCM》2003,17(20):2303-2309
In this work, a high repetition rate laser matrix-assisted laser desorption/ionization (MALDI) source is studied on a quadrupole-time-of-flight (QqTOF) and a triple quadrupole (QqQ) mass spectrometer for rapid quantification of small pharmaceutical drugs. The high repetition rate laser allows an up to 100-fold higher pulse frequency as compared with regular MALDI lasers, resulting in much larger sample throughput and number of accumulated spectra. This increases the reproducibility of signal intensities considerably, with average values being around 5% relative standard deviation after taking into account the area ratio of the analyte to an internal standard. Experiments were conducted in MS/MS mode to circumvent the large chemical background due to MALDI matrix ions in the low mass range. The dynamic range of calibration curves on the QqTOF mass spectrometer extended over at least two orders of magnitude, whereas on the QqQ it extended over at least three orders of magnitude. Detection limits ranged from 60-400 pg/microL on the QqTOF and from 6-70 pg/microL on the QqQ for a series of benzodiazepines. The benzodiazepine content of commercial pill formulations was quantified, and less than 5% error was obtained between the present method and the manufacturer's certified values. Furthermore, a high sample throughput was achieved with this method, so that a single MALDI spot could be quantitatively scanned in as little as 15 s, and an entire 96-well MALDI plate in 24 min. 相似文献
7.
Breakdowns of two-zone random networks of the Erdős–Rényi type are investigated. They are used as mathematical models for understanding the incompleteness of the tumor network breakdown under radiochemotherapy, an incompleteness that may result from a tumor’s physical and/or chemical heterogeneity. Mathematically, having a reduced node removal probability in the network’s inner zone hampers the network’s breakdown. The latter is described quantitatively as a function of reduction in the inner zone’s removal probability, where the network breakdown is described in terms of the largest remaining clusters and their size distributions. The effects on the efficacy of radiochemotherapy due to the tumor micro-environment (TME)’s chemical make-up, and its heterogeneity, are discussed, with the goal of using such TME chemical heterogeneity imaging to inform precision oncology. 相似文献
8.
Giovanni Stracquadanio Elisa Pappalardo Panos M. Pardalos 《Journal of Optimization Theory and Applications》2012,155(3):1008-1024
The design of circular antenna arrays is a challenging optimization problem, which requires ad-hoc methods to fulfill the engineering requirements. In this work, we introduce the Mesh Adaptive Basin Hopping algorithm to tackle such problem effectively; the experimental results show that the new approach proposed outperforms the state-of-the-art methods, both in terms of quality of the solutions and computational efficiency. 相似文献
9.
Tumor hypoxia was discovered a century ago, and the interference of hypoxia with all radiotherapies is well known. Here, we demonstrate the potentially extreme effects of hypoxia heterogeneity on radiotherapy and combination radiochemotherapy. We observe that there is a decrease in hypoxia from tumor periphery to tumor center, due to oxygen diffusion, resulting in a gradient of radiative cell-kill probability, mathematically expressed as a probability gradient of occupied space removal. The radiotherapy-induced break-up of the tumor/TME network is modeled by the physics model of inverse percolation in a shell-like medium, using Monte Carlo simulations. The different shells now have different probabilities of space removal, spanning from higher probability in the periphery to lower probability in the center of the tumor. Mathematical results regarding the variability of the critical percolation concentration show an increase in the critical threshold with the applied increase in the probability of space removal. Such an observation will have an important medical implication: a much larger than expected radiation dose is needed for a tumor breakup enabling successful follow-up chemotherapy. Information on the TME’s hypoxia heterogeneity, as shown here with the numerical percolation model, may enable personalized precision radiation oncology therapy. 相似文献
10.
Pando Georgiev Panos Pardalos Andrzej Cichocki 《Computational Optimization and Applications》2007,38(1):123-131
A rigorous convergence analysis for the fixed point ICA algorithm of Hyvärinen and Oja is provided and a generalization of it involving cumulants of an arbitrary order is presented. We consider a specific optimization problem OP(p), p>3, integer, arising from a Blind Source Extraction problem (BSE) and prove that every local maximum of OP(p) is a solution of (BSE) in sense that it extracts one source signal from a linear mixture of unknown statistically independent signals. An algorithm for solving OP(p) is constructed, which has a rate of convergence p?1. 相似文献