Unsteady two-layered blood flow through a w-shape stenosed artery using the generalized oldroyd-b fluid model

A theoretical study of unsteady two-layered blood flow through a stenosed artery is presented in this article. The geometry of rigid stenosed artery is assumed to be w-shaped. The flow regime is assumed to be laminar, unsteady and uni-directional. The characteristics of blood are modeled by the generalized Oldroyd-B non-Newtonian fluid model in the core region and a Newtonian fluid in the periphery region. The governing partial differential are derived for each region by using mass and momentum conservation equations. In order to facilitate numerical solutions, the derived differential equations are non-dimensionalized. A well-tested explicit finite difference scheme (FDM) which is forward in time and central in space is employed for the solution of nonlinear initial-boundary value problem corresponding to each region. Validation of the FDM computations is achieved with a variational finite element method (FEM) algorithm. The influence of the emerging geometric and rheological parameters on axial velocity, resistance impedance and wall shear stress are displayed graphically. The instantaneous patterns of streamlines are also presented to illustrate the global behavior of blood flow. The simulations are relevant to hemodynamics of small blood vessels and capillary transport wherein rheological effects are dominant

Numerical simulation of time-dependent non-Newtonian nano-pharmacodynamic transport phenomena in a tapered overlapping stenosed artery

Nanofluids are becoming increasingly popular in novel hematological treatments and also advanced nanoscale biomedical devices. Motivated by recent developments in this area, a theoretical and numerical study is described for unsteady pulsatile flow, heat and mass transport through a tapered stenosed artery in the presence of nanoparticles. An appropriate geometric expression is employed to simulate the overlapping stenosed arterial segment. The Sisko non-Newtonian model is employed for hemodynamic rheology. Buongiorno’s formulation is employed to model nanoscale effects. The two-dimensional non-linear, coupled equations are simplified for the case of mild stenosis. An explicit forward time central space (FTCS) finite difference scheme is employed to obtain a numerical solution of these equations. Validation of the computations is achieved with another numerical method, namely the variational finite element method (FEM). The effects of various emerging rheological, nanoscale and thermofluid parameters on flow and heat/mass characteristics of blood are shown via several plots and discussed in detail. The circulating regions inside the flow field are also investigated through instantaneous patterns of streamlines. The work is relevant to nanopharmacological transport phenomena, a new and exciting area of modern medical fluid dynamics which integrates coupled diffusion, viscous flow and nanoscale drug delivery mechanisms

Gastrointestinal helminthiasis presenting with acute diarrhoea and constipation: report of two cases with a second pathology.

Gastrointestinal helminthiasis in developing countries contributes to malnutrition and anemia. Diagnosis and treatment of helminthiasis, especially with low worm load is an unmet public health need in such settings. The infection may sometimes become manifest when a second pathology leads to purgation of the gastrointestinal tract. Two cases of helminthiasis are presented in which the infections only became amenable to diagnosis due to acute diarrhoea caused by giardiasis and lactulose administration. In the first case, acute giardiasis revealed Ascaris lumbricoides infestation, and in the second case primary helminthiasis (strongyloidiasis) was revealed by lactulose, and also led to Vibrio cholera bacteremia. These cases highlight the need to diagnose helminth infestations especially with low worm burdens by means of public health surveillance programmes. These cases highlight the need to diagnose helminth infestations especially with low worm burdens by means of public health surveillance programmes

Peristaltic Transport of a Couple Stress Fluid: Some Applications to Hemodynamics

The present paper deals with a theoretical investigation of the peristaltic transport of a couple stress fluid in a porous channel. The study is motivated towards the physiological flow of blood in the micro-circulatory system, by taking account of the particle size effect. The velocity, pressure gradient, stream function and frictional force of blood are investigated, when the Reynolds number is small and the wavelength is large, by using appropriate analytical and numerical methods. Effects of different physical parameters reflecting porosity, Darcy number, couple stress parameter as well as amplitude ratio on velocity profiles, pumping action and frictional force, streamlines pattern and trapping of blood are studied with particular emphasis. The computational results are presented in graphical form. The results are found to be in good agreement with those of Shapiro et. al \cite{r25} that was carried out for a non-porous channel in the absence of couple stress effect. The present study puts forward an important observation that for peristaltic transport of a couple stress fluid during free pumping when the couple stress effect of the fluid/Darcy permeability of the medium, flow reversal can be controlled to a considerable extent. Also by reducing the permeability it is possible to avoid the occurrence of trapping phenomenon

Methotrexate in rheumatoid arthritis: a 2 year experience at a university hospital in Pakistan

In this study we report our two years experience of methotrexate (MTX) in the management of rheumatoid arthritis (RA) at the Aga Khan University Hospital, Karachi. We studied the clinical course of 124 RA patients. The mean age was 44 +/- 11 years (range 19-72) and mean duration of RA was 5 +/- 4 years (range 0.3-25). Female to male ratio was 10:2.4 (100F:24M). All of them were diagnosed according to the criteria set by American Rheumatism Association. The mean value of ESR was 60 +/- 30 (Range 3-128). Fifty one percent had severe disease (\u3e 10 joints involved and evidence of erosions and deformities). Twenty-one patients had extra-articular manifestations. None of them had received MTX previously. Their kidney and liver functions were assessed to be normal. Patients were divided into two groups. One group (n = 92) received MTX (7.5-10 mg/week) as initial treatment, while the other group (n = 32) was given other disease modifying anti-rheumatic drugs (penicillamine, salazopyrin, gold, or chloroquine) followed by MTX. Assessment of the treatment outcome and development of any adverse reactions was carried out at 3-month interval over an average period of 1 year. Assessment of the treatment outcome in the group which received MTX as initial drug revealed the response to be excellent in 13%, good in 70%, fair in 11% and variable in 4%. In the group which received MTX as second-line of therapy, 59% of the patients had the response from good to excellent, while 25% of the patients exhibited poor to fair response. Regarding side-effects of MTX treatment, 57% exhibited none, while 35% had nausea and vomiting. Alopecia was the next common toxicity in these patients. Two individuals had abnormal liver function tests (value twice more than normal), while one developed lung fibrosis. MTX despite its adverse effects in some of the patients is still an effective, well tolerated and inexpensive disease modifying drug in RA

Limits on the Dipole Moments of the τ\tau-Lepton via the Process $e^{+}e^{-}\to \tau^+ \tau^- \gamma in a Left-Right Symmetric Model

Limits on the anomalous magnetic moment and the electric dipole moment of the $\tau$ lepton are calculated through the reaction $e^{+}e^{-}\to \tau^+ \tau^- \gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\phi$, the effect of this angle on the dipole moments is quite small.Comment: 15 pages, 3 figure

Biological interactions between carreau fluid and micro-swimmers in a complex wavy canal with MHD effects

The efficient magnetic swimming of actual or mechanically designed micro-swimmers within bounded regions is reliant on several factors. Few of which are: the actuation of these swimmers via magnetic field, rheology of surrounding liquid (with dominant viscous forces), nature of medium (either porous or non-porous), position (either straight, inclined or declined) and state (either active or passive) of the narrow passage. To witness these interactions, we utilize Carreau fluid with Taylor swimming sheet model under magnetic and porous effects. Moreover, the cervical canal is approximated as a two-dimensional complex wavy channel inclined at certain angle with the horizontal. The momentum equations are reduced by means of lubrication assumption, which finally leads to a fourth order differential equation. MATLAB's built-in bvp4c function is employed to solve the resulting boundary value problem (BVP). The solution obtained via bvp4c is further verified by finite difference method (FDM). In both these methods, the refined values of flow rate and cell speed are computed by utilizing modified Newton-Raphson method. These realistic pairs are further utilized, to calculate the energy delivered by the micro-swimmer. The numerical results are plotted and discussed at the end of the article. Our study explains that the optimum speed of the micro-organism can be achieved by means of exploiting the fluid rheology and with the suitable application of the magnetic field. The peristaltic nature of the channel walls and porous medium may also serve as alternative factors to control the speed of the propeller