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81.
Zouros GP 《Journal of the Optical Society of America. A, Optics, image science, and vision》2011,28(11):2376-2384
The electromagnetic scattering by an arbitrarily oriented elliptical cylinder having different constitutive parameters than those of the background medium is treated in this work. The separation of variables method is used to solve this problem, but, due to the oblique incidence of the source fields, hybrid waves for the scattered and induced fields are generated, thus making the formulation complicated. Moreover, because of the different wavenumbers between the scatterer and the background medium, the orthogonality relations for Mathieu functions do not hold, leading to more complicated systems, compared to those of normal incidence, which should be solved in order to obtain the solution for the scattered or induced fields. The validation of the results reveals the high accuracy of the implementation, even for electrically large scatterers. Both polarizations are considered and numerical results are given for various values of the parameters. The method is exact and can be used for reference as an alternative validation for future methods involving scattering problems. 相似文献
82.
Papathanasiou G White KN Walton R Boult S 《The Science of the total environment》2011,409(24):5277-5283
Extension of the conditions under which Al toxicity is tested is required. Environmentally representative preparation of waters is used in investigating roles of alginate (AA) and humic acids (HA) in partitioning of Al (0.5 mg L− 1), subsequent uptake and accumulation by and toxicity to Lymnaea stagnalis. HA and AA did not alter precipitation of Al(OH)3, but altered subsequent behaviour of Al. High (40 mg L− 1) HA concentrations, and to a lesser extent AA, prevented settling and availability for benthic grazing but made deposited Al more likely to be ingested. HA detoxified but AA increased toxicity relative to Al alone. Low concentration (4 mg L− 1) AA and HA do not change partitioning but increase uptake; they both detoxify, but AA less than HA. The study shows OC:Al ratio is critical in predicting Al behaviour in natural waters, also uptake is mediated by snail behaviour, not solely a function of concentration and form of Al. Therefore, predicting Al behaviour will be subject to errors in determining relevant water composition and response of biota to the new speciation. However, with respect to toxicity, rather than other aspects of Al behaviour, different ratios of HA and Al are insignificant compared to whether AA is present rather than HA. 相似文献
83.
Christos Vallilas Panagiotis Sarantis Anastasios Kyriazoglou Evangelos Koustas Stamatios Theocharis Athanasios G. Papavassiliou Michalis V. Karamouzis 《International journal of molecular sciences》2021,22(2)
Gastrointestinal stromal tumors (GISTs) are the most common types of malignant mesenchymal tumors in the gastrointestinal tract, with an estimated incidence of 1.5/100.000 per year and 1–2% of gastrointestinal neoplasms. About 75–80% of patients have mutations in the KIT gene in exons 9, 11, 13, 14, 17, and 5–10% of patients have mutations in the platelet-derived growth factor receptor a (PDGFRA) gene in exons 12, 14, 18. Moreover, 10–15% of patients have no mutations and are classified as wild type GIST. The treatment for metastatic or unresectable GISTs includes imatinib, sunitinib, and regorafenib. So far, GIST therapies have raised great expectations and offered patients a better quality of life, but increased pharmacological resistance to tyrosine kinase inhibitors is often observed. New treatment options have emerged, with ripretinib, avapritinib, and cabozantinib getting approvals for these tumors. Nowadays, immune checkpoint inhibitors form a new landscape in cancer therapeutics and have already shown remarkable responses in various tumors. Studies in melanoma, non-small-cell lung cancer, and renal cell carcinoma are very encouraging as these inhibitors have increased survival rates. The purpose of this review is to present alternative approaches for the treatment of the GIST patients, such as combinations of immunotherapy and novel inhibitors with traditional therapies (tyrosine kinase inhibitors). 相似文献
84.
Artemisia Spanaki Dionysia Kolokotsa Theocharis Tsoutsos Ilias Zacharopoulos 《Solar Energy》2012,86(11):3331-3344
The present study focuses on the research of a new passive roof cooling technique, based on the combination of low emissivity materials and water. A novel roof pond is chosen as the most advantageous in terms of both energy efficiency and less maintenance or functional demands. The pond – referred as “Roof Pond with Gunny Bag” (RPWGB) – is covered by a cloth floating on water level, encouraging evaporative heat losses. A mathematical model describing the energy flux through the RPWGB is developed. The following sensitivity analysis marks the parameters that reduce bottom pond temperature thus improving the efficiency of the system. The experimental study analyses alternative ways to reduce bottom pond temperature. For this purpose, the low emissivity material is placed in different positions, above, below and floating on water level. Heat dissipation occurs by means of radiation losses and water evaporation. 相似文献
85.
Sotiris Nikoletseas Grigorios Prasinos Paul Spirakis Christos
Zaroliagis 《Theory of Computing Systems》2003,36(5):553-574
A new model for intrusion and its propagation through
various attack schemes in networks is
considered. The model is characterized by the number of
network nodes n, and two parameters f and g.
Parameter f represents the probability of failure of an attack
to a node and is a gross measure of the level of security of the attacked
system and perhaps of the intruder’s skills; g represents a limit on the
number of attacks that the intrusion software can ever try, due to the danger
of being discovered, when it issues them from a particular (broken) network node.
The success of the attack scheme is characterized
by two factors: the number of nodes captured (the spread factor)
and the number of virtual links that a defense mechanism has to
trace from any node where the attack is active to the origin
of the intrusion (the traceability factor).
The goal of an intruder is to maximize both factors.
In our model we present four different ways (attack schemes) by
which an intruder can organize his attacks. Using analytic
and experimental methods, we first show that for any 0 < f < 1,
there exists a constant g for which any of
our attack schemes can achieve a Θ(n) spread and traceability factor
with high probability, given sufficient propagation time. We also show
for three of our attack schemes that the spread and the traceability
factors are, with high probability, linearly related
during the whole duration of the attack propagation. This implies that
it will not be easy for a detection mechanism to trace the
origin of the intrusion, since it will have to trace a number
of links proportional to the nodes captured. 相似文献
86.
S. E. Papadakis J. B. Theocharis 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2006,10(9):805-824
This paper proposes a genetic-based algorithm for generating simple and well-defined Takagi-Sugeno-Kang (TSK) models. The method handles several attributes simultaneously, such as the input partition, feature selection and estimation of the consequent parameters. The model building process comprises three stages. In stage one, structure learning is formulated as an objective weighting optimization problem. Apart from the mean square error (MSE) and the number of rules, three additional criteria are introduced in the fitness function for measuring the quality of the partitions. Optimization of these measures leads to models with representative rules, small overlapping and efficient data cover. To obtain models with good local interpretation, the consequent parameters are determined using a local MSE function while the overall model is evaluated on the basis of a global MSE function. The initial model is simplified at stage two using a rule base simplification routine. Similar fuzzy sets are merged and the “don’t care” premises are recognized. Finally, the simplified models are fine-tuned at stage three to improve the model performance. The suggested method is used to generate TSK models with crisp and polynomial consequents for two benchmark classification problems, the iris and the wine data. Simulation results reveal the effectiveness of our method. The resulting models exhibit simple structure, interpretability and superior recognition rates compared to other methods of the literature. 相似文献
87.
Paris A Mastorocostas John B Theocharis 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(2):242-254
A novel learning algorithm, the Recurrent Neural Network Constrained Optimization Method (RENNCOM) is suggested in this paper, for training block-diagonal recurrent neural networks. The training task is formulated as a constrained optimization problem, whose objective is twofold: (1) minimization of an error measure, leading to successful approximation of the input/output mapping and (2) optimization of an additional functional, the payoff function, which aims at ensuring network stability throughout the learning process. Having assured the network and training stability conditions, the payoff function is switched to an alternative form with the scope to accelerate learning. Simulation results on a benchmark identification problem demonstrate that, compared to other learning schemes with stabilizing attributes, the RENNCOM algorithm has enhanced qualities, including, improved speed of convergence, accuracy and robustness. The proposed algorithm is also applied to the problem of the analysis of lung sounds. Particularly, a filter based on block-diagonal recurrent neural networks is developed, trained with the RENNCOM method. Extensive experimental results are given and performance comparisons with a series of other models are conducted, underlining the effectiveness of the proposed filter. 相似文献
88.
Due to the competitiveness the importance of reducing cost and the growing sensitivity to environmental factors in the hotel design, is leading to the introduction of environmental friendly elements; if will be added the considerable increase in the cost of fossil fuel, it is obvious that all these factors create conditions favorable to the optimization of energy resources. 相似文献
89.
Ioannis Pashalidis Charis R. Theocharis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1998,71(3):223-226
The surface properties of commercial grade calcium hydroxide were studied by nitrogen adsorption isotherm analysis, FTIR spectroscopy (KBr transmission and reflectance) and TGA analysis before and after toluene adsorption. Experimental results show that the surface texture of calcium hydroxide is little affected despite the relatively high amounts of adsorbed toluene and that the organic molecules are strongly bonded onto the solid, and on internal surfaces which are accessible through slit-shaped openings. © 1998 SCI 相似文献
90.
Dimitrios Goutas Alexandros Pergaris Nikolaos Goutas Stamatios Theocharis 《International journal of molecular sciences》2022,23(7)
Exosomes are cell-secreted nanoparticles containing various molecules including small vesicles, microRNAs (miRNAs), messenger RNAs or bioactive proteins which are thought to be of paramount importance for intercellular communication. The unique effects of exosomes in terms of cell penetration capacity, decreased immunogenicity and inherent stability, along with their key role in mediating information exchange among tumor cells and their surrounding tumor microenvironment (TME), render them a promising platform for drug targeted delivery. Compared to synthetic drugs, exosomes boast a plethora of advantages, including higher biocompatibility, lower toxicity and increased ability of tissue infiltration. Nevertheless, the use of artificial exosomes can be limited in practice, partly due to their poor targeting ability and partly due to their limited efficacy. Therefore, efforts have been made to engineer stem cell-derived exosomes in order to increase selectiveness and effectivity, which can then become loaded with various active substances depending on the therapeutic approach followed. Erythropoietin-producing human hepatocellular receptors (EPHs), along with their ligands, the EPH family receptor interacting proteins (ephrins), have been extensively investigated for their key roles in both physiology and cancer pathogenesis. EPHs/ephrins exhibit both tumorigenic and tumor suppressing properties, with their targeting representing a promising, novel therapeutic approach in cancer patients’ management. In our review, the use of ephrin-loaded exosomes as a potential therapeutic targeted delivery system in cancer will be discussed. 相似文献