Simulation of Blood Flow through Stenosed Artery

Atherosclerosis is a life-threatening disease of the human circulatory system. It can lead to blockage of arteries leading to heart attacks. It is characterized by plaque formation at the walls of the artery lumen. The progression of plaque formation can lead to complete blockage of the artery. The diagnosis of atherosclerosis is very important. So, the study of parameters affecting atherosclerosis is important. We study the effect of percentage blockage and non-Newtonian nature of blood on hydrodynamic factors in an artery that is partially blocked by atherosclerotic plaque. ANSYS Fluent software is used to study these cases. We obtain the velocity profile and wall shear stress profile for 10%, 25%, 50%, and 75% blockage. We also study the effect of various blood models like Newtonian, Power law, Carreau, and Cross models on the fluid dynamic factors. Results show that the percentage of stenosis affects the wall shear stress (WSS) the most. WSS is minimum for 10% stenosis, and maximum for 75% stenosis. The fluctuation of WSS, downstream of the stenosis, is also maximum for the case of 75% stenosis and minimum for the case of 10% stenosis. There is formation of a recirculation zone, downstream of the stenosis, for all models at 50% stenosis

Concept Drift Detection in Data Stream Mining: The Review of Contemporary Literature

Mining process such as classification, clustering of progressive or dynamic data is a critical objective of the information retrieval and knowledge discovery; in particular, it is more sensitive in data stream mining models due to the possibility of significant change in the type and dimensionality of the data over a period. The influence of these changes over the mining process termed as concept drift. The concept drift that depict often in streaming data causes unbalanced performance of the mining models adapted. Hence, it is obvious to boost the mining models to predict and analyse the concept drift to achieve the performance at par best. The contemporary literature evinced significant contributions to handle the concept drift, which fall in to supervised, unsupervised learning, and statistical assessment approaches. This manuscript contributes the detailed review of the contemporary concept-drift detection models depicted in recent literature. The contribution of the manuscript includes the nomenclature of the concept drift models and their impact of imbalanced data tuples

Near Field Lenses in Two Dimensions

It has been shown that a slab of materials with refractive index = -1 behaves like a perfect lens focussing all light to an exact electromagnetic copy of an object. The original lens is limited to producing images the same size as the object, but here we generalise the concept so that images can be magnified. For two dimensional systems, over distances much shorter than the free space wavelength, we apply conformal transformations to the original parallel sided slab generating a variety of new lenses. Although the new lenses are not `perfect' they are able to magnify two dimensional objects. The results apply equally to imaging of electric or magnetic sub wavelength objects in two dimensions. The concepts have potential applications ranging from microwave frequencies to the visible.Comment: PDF fil

Probiotic-induced changes in the intestinal epithelium: Implications in gastrointestinal disease

There is resurgent interest in the use of probiotics to maintain gastrointestinal and systemic health, driven by recent advances in knowledge of bacterial interactions with the epithelium and innate immune system of the intestine. The effects of probiotic bacteria on the intestinal epithelium and their downstream consequences are reviewed. Probiotics prevent pathogen adherence and invasion of the epithelium, partly by blocking adherence sites but also by upregulating gene expression of MUC2 and of antimicrobial peptides. Metabolic effects of probiotics on the intestinal epithelium include production of short chain fatty acids which influence epithelial cell metabolism, turnover and apoptosis. Bacterial metabolism of unabsorbed dietary constituents with production of free radicals and phenolic metabolites can lead to DNA damage and cancer; probiotics restore eubiosis and potentially prevent this. Probiotics alter expression and redistribution of tight junction proteins and reduce intestinal permeability limiting absorption of noxious molecules from the gut lumen. Most studied are the effects of probiotics on epithelial cells which are the first line of innate immune-capable cells that encounter luminal flora. Probiotics, through secreted molecules, influence the innate inflammatory response of epithelial cells to stimuli from the gut lumen, and reduce mucosal inflammation. Through effects on dendritic, and possibly epithelial, cells they influence naïve T cells in the lamina propria of the gut and thus influence adaptive immunity. These varied effects of probiotics have implications for the treatment of several gastrointestinal diseases including antibiotic-associated colitis, acute gastroenteritis, inflammatory bowel disease, colon cancer, and irritable bowel syndrome

Aircraft interior noise reduction by alternate resonance tuning

Existing interior noise reduction techniques for aircraft fuselages perform reasonably well at higher frequencies, but are inadequate at lower frequencies, particularly with respect to the low blade passage harmonics with high forcing levels found in propeller aircraft. A method is being studied which considers aircraft fuselage lined with panels alternately tuned to frequencies above and below the frequency that must be attenuated. Adjacent panels would oscillate at equal amplitude, to give equal source strength, but with opposite phase. Provided these adjacent panels are acoustically compact, the resulting cancellation causes the interior acoustic modes to become cutoff, and therefore be non-propagating and evanescent. This interior noise reduction method, called Alternate Resonance Tuning (ART), is currently being investigated both theoretically and experimentally. This new concept has potential application to reducing interior noise due to the propellers in advanced turboprop aircraft as well as for existing aircraft configurations

On the refractive index for a nonmagnetic two-component medium: resolution of a controversy

The refractive index of a dielectric medium comprising both passive and inverted components in its permittivity was determined using two methods: (i) in the time domain, a finite-difference algorithm to compute the frequency-domain reflectance from reflection data for a pulsed plane wave that is normally incident on a dielectric half-space, and (ii) in the frequency domain, the deflection of an obliquely incident Gaussian beam on transmission through a dielectric slab. The dielectric medium was found to be an active medium with a negative real part for its refractive index. Thereby, a recent controversy in the scientific literature was resolved.Comment: manuscript submitted to Optics Communication

Power spectrum of mass and activity fluctuations in a sandpile

We consider a directed abelian sandpile on a strip of size $2\times n$, driven by adding a grain randomly at the left boundary after every $T$ time-steps. We establish the exact equivalence of the problem of mass fluctuations in the steady state and the number of zeroes in the ternary-base representation of the position of a random walker on a ring of size $3^n$. We find that while the fluctuations of mass have a power spectrum that varies as $1/f$ for frequencies in the range $3^{-2n} \ll f \ll 1/T$, the activity fluctuations in the same frequency range have a power spectrum that is linear in $f$.Comment: 8 pages, 10 figure

Redesign of a Master\u27s in Information Systems Curriculum: The Influence of Global Sourcing

We present a case study of a successful response to outsourcing, and IS job and enrollment declines through an IS curriculum redevelopment in a business school. First, we examine literature on outsourcing/offshoring phenomenon and on IS curricular redesign. A conceptual framework is presented that is useful in understanding the role of global collaborative group projects for learning about outsourcing in the IS graduate curriculum. A case study of one approach to an IS graduate curriculum redesign is then presented. The case examines the results of a survey of IT executives that informed the design of the curriculum. The case study curriculum is compared to the MSIS 2006 national model, and results are interpreted from prior literature and workforce trends