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Wyszukujesz frazę "Roy, R." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
Mathematical modeling of fluid flow in brain tumor
Autorzy:
Riahi, D. N.
Roy, R.
Powiązania:
https://bibliotekanauki.pl/articles/280794.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
tumor
brain tumor
spherical tumor
drug concentration
fluid flow
Opis:
We consider the problem of fluid flow in a brain tumor. We develop a mathematical model for the one-dimensional fluid flow in a spherical tumor where the spatial variations of the interstitial velocity, interstitial pressure and the drug concentration within the tumor are only with respect to the radial distance from the center of the tumor. The interstitial ve- locity in the radial direction and the interstitial pressure are determined analytically, while the radial variations of two investigated drug concentrations were determined numerically. We calculated these quantities in the tumor, in a corresponding normal tissue and for the concentrations also in the cavity that can exist after the tumor is removed. We determine, in particular, the way the interstitial pressure and velocity vary, which agrees with the expe- riments, as well as the way one drug concentration changes in the presence or absence of a second drug concentration within the tumor. We find that the amount of drug delivery in the tumor can be enhanced in the presence of another drug in the tumor, while the ratio of the amount of one drug in the tumor to its amount in the normal tissue can be reduced in the presence of the second drug in the tumor and the tissue.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 1; 271-279
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-phase flow in a catheterized artery with atherosclerosis
Dwufazowy przepływ krwi w tętnicy ze zmianami miażdżycowymi po wykonanym zabiegu koronarografii
Autorzy:
Ledesma, J. M.
Riahi, D. N.
Roy, R.
Powiązania:
https://bibliotekanauki.pl/articles/281424.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
arterial flow
blood flow
impedance
atherosclerosis
pressure
shear stress
Opis:
We consider the problem of blood flow in a catheterized artery and in the presence of atherosclerosis, which is chosen based on the available experimental data. The atherosclerosis is a condition where an artery wall thickens as a result of fatty materials such as cholesterol. The use of catheter is of immense importance as a standard tool for diagnosis and treatment in a patience whose artery is affected adversely by the presence of atherosclerosis within the artery. The blood flow in the arterial tube is represented by a two-phase model composing a suspension of erythrocytes (red cells) in plasma. The coupled differential equations for both fluid (plasma) and particles (red cells) are solved theoretically subjected to reasonable modeling and approximations. The important quantities such as plasma speed, velocity of red cells, blood pressure force, impedance (blood flow resistance) and the wall shear stress are computed for different values of the catheter size, axial location of atherosclerosis and the hematocrit due to the red cells-plasma combination of the blood flow system.
W pracy omówiono problem przepływu krwi w tętnicy po zabiegu koronarografii w obecności zmian miażdżycowych, opierając się na osiągalnych danych z badań klinicznych. Miażdżycą nazywamy stan, w którym ściana tętnicy pogrubia się do wewnątrz wskutek odkładania się tłuszczy, głownie cholesterolu. W standardowej metodzie leczenia miażdżycy stosuje się zabieg koronarografii polegający na wprowadzeniu cewnika do upośledzonej tętnicy. W pracy opisano przepływ krwi w przekroju tętnicy za pomocą dwufazowego modelu odzwierciedlającego zawiesinę czerwonych ciałek krwi w osoczu. Sprzężone, różniczkowe równania przepływu płynu (osocza) i ruchu cząstek (czerwonych ciałek) rozwiązano analitycznie w stopniu akceptowalnie przybliżonym. Tak istotne wielkości, jak prędkość przepływu osocza, prędkość czerwonych ciałek, ciśnienie krwi, impedancja (opory przepływu) oraz naprężenia ścinające w ścianie tętnicy obliczono dla rożnych rozmiarów cewnika, osiowego rozkładu złogów miażdżycowych oraz hematokrytu wywołanego dwufazową kombinacją czerwone ciałka-osocze w badanym układzie krwionośnym.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 409-418
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The seasonal incidence of parasitic helminth infection among the walking catfish, Clarias batrachus of Tripura, India
Autorzy:
Koiri, R.
Roy, B.
Powiązania:
https://bibliotekanauki.pl/articles/5861.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Parazytologiczne
Opis:
In the present study, a total of 868 walking catfish, Clarias batrachus, were collected during the period of April, 2012 to March, 2015, to evaluate the prevalence of helminth parasites from different parts of Tripura, Northeast India. Of these, 606 fish were found to be infected with one genus of trematode viz., Astiotrema, two genera of cestode viz., Lytocestus and Djombangia and one genus of nematode parasite viz., Anisakis. Of the three groups of parasites recovered, the major group infecting the host were found to be cestodes, followed by nematodes and trematodes. Seasonal studies show that the overall prevalence of the collected helminth parasites was highest during the postmonsoon season, followed by the monsoon and pre-monsoon seasons.
Źródło:
Annals of Parasitology; 2016, 62, 4
0043-5163
Pojawia się w:
Annals of Parasitology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady MHD mixed convection flow of a micropolar fluid over a vertical wedge
Autorzy:
Roy, N. C.
Gorla, R. S. R.
Powiązania:
https://bibliotekanauki.pl/articles/264759.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
micropolar fluid
unsteady flow
radiation
heat generation
płyn mikropolarny
przepływ nieustalony
promieniowanie
wytwarzanie ciepła
Opis:
An analysis is presented to investigate the unsteady magnetohydrodynamic (MHD) mixed convection boundary-layer flow of a micropolar fluid over a vertical wedge in the presence of thermal radiation and heat generation or absorption. The free-stream velocity and surface temperature are assumed to be oscillating in magnitude but not in the direction of the oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the finite difference method for the entire frequency range, and the series solution for low frequency range and the asymptotic series expansion method for the high frequency range. Numerical solutions provide a good agreement with the series solutions. The amplitudes of skin friction and couple stress coefficients are found to be strongly dependent on the Richardson number and the vortex viscosity parameter. The Prandtl number, the conduction-radiation parameter, the surface temperature parameter and the pressure gradient parameter significantly affect the amplitudes of skin friction, couple stress and surface heat transfer rates. However, the amplitudes of skin friction coefficient are considerably affected by the magnetic field parameter, whereas the amplitudes of heat transfer rate are appreciably changed with the heat generation or absorption parameter. In addition, results are presented for the transient skin friction, couple stress and heat transfer rate with the variations of the Richardson number, the vortex viscosity parameter, the pressure gradient parameter and the magnetic field parameter.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 2; 363-391
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Power High-Speed Double Gate 1-bit Full Adder Cell
Autorzy:
Kumar, R.
Roy, S.
Bhunia, C. T.
Powiązania:
https://bibliotekanauki.pl/articles/226653.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
low-power full-adder
low-power CMOS design
multiplexer based full-adder design
multi-threshold voltage based full-adder design
pass transmission logic
Opis:
In this paper, we proposed an efficient full adder circuit using 16 transistors. The proposed high-speed adder circuit is able to operate at very low voltage and maintain the proper output voltage swing and also balance the power consumption and speed. Proposed design is based on CMOS mixed threshold voltage logic (MTVL) and implemented in 180nm CMOS technology. In the proposed technique the most time-consuming and power consuming XOR gates and multiplexer are designed using MTVL scheme. The maximum average power consumed by the proposed circuit is 6.94μW at 1.8V supply voltage and frequency of 500 MHz, which is less than other conventional methods. Power, delay, and area are optimized by using pass transistor logic and verified using the SPICE simulation tool at desired broad frequency range. It is also observed that the proposed design may be successfully utilized in many cases, especially whenever the lowest power consumption and delay are aimed.
Źródło:
International Journal of Electronics and Telecommunications; 2016, 62, 4; 329-334
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modeling to optimize the product in enzyme kinetics
Autorzy:
Nandi, S.
Ghosh, M. K.
Bhattacharya, R.
Roy, P. K.
Powiązania:
https://bibliotekanauki.pl/articles/206501.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
enzyme kinetics
optimization
optimal control approach
reversible reaction
Opis:
Optimization of product in enzyme kinetics is successful by the showers of mathematical analysis with control measures. Enzymes are an important functional aspects of all biochemical processes, as they catalyze numerous reaction taking place within living organisms. With this view, optimization and quantification of product is stressed upon and in such a context, optimal control approaches have been applied in our study. In this article, we have formulated a mathematical model of enzymatic system Dynamics with control measures with a view to optimize the product as well as process conditions. Here, Pontryagin Minimum Principle is used for determination of optimal control with the help of Hamiltonian. We discuss the relevant numerical solutions for the concentration of substrate, enzyme, complex and product with respect to a specified time interval by varying control factors.
Źródło:
Control and Cybernetics; 2013, 42, 2; 431-442
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sequence of post-moult exoskeleton hardening preserved in a trilobite mass moult assemblage from the Lower Ordovician Fezouata Konservat-Lagerstätte, Morocco
Autorzy:
Drage, H.B.
Vandenbroucke, T.R.A.
Van Roy, P.
Daley, A.C.
Powiązania:
https://bibliotekanauki.pl/articles/20934.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Euarthropods have a tough exoskeleton that provides crucial protection from predation and parasitism. However, this is restrictive to growth and must be periodically moulted. The moulting sequence is well-known from extant arthropods, consisting of: (i) the long inter-moult stage, in which no changes occur to the hardened exoskeleton; (ii) the pre-moult stage where the old exoskeleton is detached and the new one secreted; (iii) exuviation, when the old exoskeleton is moulted; and (iv) the post-moult stage during which the new exoskeleton starts as soft, thin, and partially compressed and gradually hardens to the robust exoskeleton of the inter-moult stage. Trilobite fossils typically consist of inter-moult carcasses or moulted exuviae, but specimens preserving the post-moult stage are rare. Here we describe nine specimens assigned to Symphysurus ebbestadi representing the first group of contemporaneous fossils collected that preserve all key stages of the moulting process in one taxon, including the post-moult stage. They were collected from a single lens in the Tremadocian part of the Fezouata Shale Formation, Morocco. Based on cephalic displacement and comparison to other trilobite moults, one specimen appears to represent a moulted exoskeleton. Four specimens are typical inter-moult carcasses. Four others are wrinkled and flattened, with thin exoskeletons compared to inter-moult specimens, and are considered post-moult individuals. These S. ebbestadi specimens illuminate the preservation and morphology of the post-moulting stage, characterised by strong anterior-posterior exoskeleton wrinkling, as well as overall body flattening and reduced visibility of thoracic articulations. Being found in the same lens, these specimens likely represent the first preserved in-the-act mass moulting event. The displayed sequence of moulting suggests the moulting process in trilobites was comparable to modern arthropods, and conserved within euarthropod evolutionary history.
Źródło:
Acta Palaeontologica Polonica; 2019, 64, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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