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Search Results: 1 - 10 of 289 matches for " Zdenek Chara "
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Drag reduction of dense fine-grained slurries
Pavel Vlasak, Zdenek Chara, Petr Stern
Journal of Hydrology and Hydromechanics , 2010, DOI: 10.2478/v10098-010-0024-y
Abstract: Attractive and repulsive forces acting in the slurry due to different ions absorbed on surface of fine particles, especially colloidal ones, strongly affect the flow behaviour of highly concentrated fine-grained slurries. The attractive forces between the fine-grained solid particles initiate the coagulation process, which gives rise to voluminous aggregates where a large amount of water is fixed. A modification of the physical-chemical environment of the slurry by addition of a peptizing agent produces repulsive forces between particles. They result in destruction of the aggregates, water originally fixed in the aggregates is liberated, the viscous friction can play a larger role in the slurry, which is liquefied. To prove these process three different kaolin-water mixtures were tested with an overpressure capillary viscometer, rotational viscometer, and experimental pipeline loop. The effect of two peptizing agents and their concentration was investigated. It was demonstrated that even very low concentration of peptizing agent results in a significant reduction in the apparent viscosity and in the yield stress.
Numerical model of spherical particle saltation in a channel with a transversely tilted rough bed
Nikolay Lukerchenko, Siarhei Piatsevich, Zdenek Chara, Pavel Vlasak
Journal of Hydrology and Hydromechanics , 2009, DOI: 10.2478/v10098-009-0017-x
Abstract: This paper deals with the numerical simulation of spherical particle saltation in a channel with a rough transversely tilted bed. The numerical model presented is based on the 3D model of spherical particle saltation developed by the authors, which takes into account the translational and rotational particle motion. The stochastic method and the concept of a contact zone were used for the calculation of a particle trajectory and its dependence on the bed lateral slope, particle diameter, and shear velocity. The effect of the bed lateral slope results in a deviation of the particle trajectory from the downstream direction. Some examples of the calculation are presented. The trajectories of the saltating particles starting their movements from one point were calculated and it was shown that they are of random character and together create a bundle or fascicle of trajectories. It was found that the centrelines of the bundles can be approximated by the straight lines for low and moderate values of the bed transverse slope, i.e. slopes less than 20°. The angle of deviation of the centreline from the downstream direction increases when the bed lateral slope and/or the particle diameters increase. However, with increasing shear velocity, the deviation angle decreases. Due to the lateral bed slope the particles are sorted according to their size, and the criteria for sorting particles were defined. An example of the particle sorting was calculated and the separable and non-separable regions were determined.
Cellular Profiles in Peripheral Blood Accompanying Particular Asthmatic Response Types  [PDF]
Zdenek Pelikan
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.36088
Abstract: Background: Patients with allergic bronchial asthma develop various asthmatic response types to bronchial challenge with allergen, such as immediate (IAR), late (LAR), dual late (DLAR) or delayed (DYAR), displaying different clinical, immunologic and pharmacologic features. This study deals with count changes of particular blood cells accompanying the IAR, LAR and DYAR. Methods: In 63 patients developing 22 IAR, 26 LAR and 15 DYAR, the repeated allergen challenges were supplemented with recording of blood cell counts, Th1/Th2 ratio, leukotrines B4 (LTB4) and C4 (LTC4), eosinophil cationic protein (ECP), myeloperoxidase (MPO), and histamine in blood, and intracellular IFN-γ and IL-4 in peripheral blood mononuclear cells. Results: The IAR was accompanied by increased eosinophil and basophil counts, increased serum concentrations of histamine, LTC4 and ECP, decreased Th1/Th2 ratio in favour of Th2 cells, and increased intracellular IL-4. The LAR was associated with increased eosinophil and neutrophil counts, increased serum concentrations of LTC4 and LTB4, unchanged Th1/Th2 ratio, and increased intra-cellular IL-4. The DYAR was accompanied by increased total leukocyte, neutrophil, monocyte, lymphocyte and thrombocyte counts, increased serum concentrations of LTB4 and MPO, increased Th1/Th2 ratio in favour of Th1 cells, and increased intracellular IFN-γ. Conclusions: These results provide evidence for different involvement of particular blood cell types and different hypersensitivity mechanisms in IAR, LAR and DYAR. The monitoring of peripheral blood cell counts seems to be an useful supplementary parameter to the bronchial challenge with allergen.
Cytokines Released from Allergen-Stimulated Blood Cells during the Delayed Asthmatic Response to Allergen Challenge  [PDF]
Zdenek Pelikan
International Journal of Clinical Medicine (IJCM) , 2014, DOI: 10.4236/ijcm.2014.56049

Background: Bronchial asthma patients may develop various asthmatic response types to bronchial challenge with allergen, such as immediate (IAR), late (LAR), dual (DAR) or delayed (DYAR), due to different immunologic mechanisms. The DYAR, beginning between 26-32 hrs and lasting up to 56 hrs after the allergen challenge, differs from the IAR, LAR and DAR in clinical, diagnostic and immunologic aspects. The aim of this study was to investigate the concentrations of the particular intracellular cytokines released by blood cells stimulated with relevant allergens “in vitro”, before and during the DYAR. Methods: In 23 patients, the repeated DYAR (p < 0.001) was supplemented with cytokine determination in the supernatants of the blood cells stimulated with relevant allergens before and up to 72 hours after the bronchial challenge, by means of enzyme-linked immunoassay. Results: The significantly elevated pre-challenge concentrations (p < 0.05) of IL-2, IL-17, IFN-γ and G-CSF released by allergen-stimulated blood cells “in vitro” were recorded in the DYAR patients as compared with healthy controls. The significantly increased post-challenge concentrations (

Preventing Psychosocial Problems and Promoting Health-Related Quality of Life in Children and Adolescents Struggling with Parental Depression  [PDF]
George Giannakopoulos, Chara Tzavara, Gerasimos Kolaitis
Open Journal of Depression (OJD) , 2015, DOI: 10.4236/ojd.2015.42003
Abstract: Parental depression has a devastating impact on family life and children’s social adjustment and mental health and little information exists as to how parental depression is associated with children’s health-related quality of life. The present paper describes the research protocol of a Greek randomized clinical trial, examining the effectiveness of two preventive interventions (a family intervention and a psychoeducational discussion with parents) for families struggling with parental depression. An important question in this research is what factors can better predict the improvement of child outcomes in these families. Another issue of special interest is to explore the association of children’s health-related quality of life with parental mental health symptoms and to examine to what extent each intervention can have a positive impact on this domain. Sixty-two patients diagnosed with depressive disorders and their offspring aged 8 - 16 years old are randomly assigned to the two intervention groups and they complete a series of questionnaires prior to interventions and 4, 10 and 18 months after intervention. This study will offer an evidence base for developing relevant initiatives in a national level and for integrating preventive actions for child mental health in routine clinical practice with adult depressed patients.
La primera botica de los hospitales de la ciudad de lima en el siglo XVI
Rabí Chara, Miguel
Asclepio : Revista de Historia de la Medicina y de la Ciencia , 2000,
Abstract: The first hospitals established in south America, specifically in Lima in 1549, are reviewed by the author, hightlighting the first pharmacy arrived in 1551 for those hospitals, including the complete inventary and values of it's contents. In the same way the contract for its management is described and analyzed. El autor hace una rese a detallada sobre los primeros hospitales establecidos en la Ciudad de los Reyes de Lima, a partir de 1549; y en especial un comentario sobre la primera botica recibida en 1551 para dichos hospitales, junto con el contrato de compa ía para su funcionamiento.
Gentiles! No por dinero, sino por sue o
Juan Alberto Chara Suero
Anthropologica , 1985,
Abstract: El artículo no presenta resumen.
The Picard Fuchs equations for complete hyperelliptic integrals of even order curves, and the actions of the generalized Neumann system
Yuri Fedorov,Chara Pantazi
Mathematics , 2012,
Abstract: We consider a family of genus 2 hyperelliptic curves of even order and obtain explicitly the system of 5 linear ODEs for periods of the corresponding Abelian integrals of first, second, and third kind, as functions of the parameters of the curves. The system is an extention of the well studied Picard--Fuchs equations for periods of complete integrals of first and second kind on odd hyperelliptic curves. The periods we consider are linear combinations of the action variables of several integrable systems, in particular the generalized Neumann system with polynomial separable potentials. Thus the solutions of the extended Picard--Fuchs equations can be used to study various properties of the actions.
Asymptotically bad towers of function fields
M. Chara,R Toledano
Mathematics , 2014,
Abstract: In this paper we study general conditions to prove the infiniteness of the genus of certain towers of function fields over a perfect field. We show that many known examples of towers with infinite genus are particular cases of these conditions.
On cubic Kummer towers of Garcia, Stichtenoth and Thomas type
M. Chara,R Toledano
Mathematics , 2014,
Abstract: In this paper we initiate the study of the class of cubic Kummer type towers considered by Garcia, Stichtenoth and Thomas in 1997 by classifying the asymptotically good ones in this class.
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