Optimization of slice thickness in multispectral MRI tissue classification of brain tissues

In recent years, magnetic resonance imaging has proven to be an important imaging modality for diagnosing and locating pathology. Recent studies have shown that multispectral tissue classification (MTC) may segment pathology from healthy tissues. Several studies have been done to classify brain tissues such as white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) using MTC with slice thicknesses ranging from 5 to 10 mm (Kohn, 1991; Fletcher, 1993; Kao, 1994). In one of the previous studies (Fletcher, 1993) MTC has been used to classify brain tissues such as WM, GM, CSF, adipose tissue (AD), muscle (MS) and skin and meninges (S&M) with a slice thickness of 5 mm. The chosen slice thickness in the above mentioned studies is not quantified. Therefore a question remains as to what is the optimum slice thickness for MTC of brain tissues. The purpose of this research is to evaluate the ability of MTC to segment the brain tissues as a function of slice thickness using spectral regions such as spin-lattice relaxation time (TO, spin-spin relaxation time (T2), and spin density (p). The slice thicknesses used in the study were 3 mm, 5 mm, and 10 mm. Raw spin-echo images were acquired from a 39 year old volunteer at the level of lateral ventricles through the brain on a General Electric (Milwaukee, WI) 1.5 Tesla Signa imager with quadrature bird cage head coil. Ti, and p images were calculated from a set of seven raw spin-echo images using non-linear least square procedure (Gong, 1992) with varying repetition time (TR) and a constant echo time (TE). Similarly T2 images were calculated from a set of eight raw images using linear least square fit algorithm (Li, 1993) with varying TE and constant TR images. The Ti, T2, and p images were calculated for 3, 5, and 10 mm slice thicknesses. The ability to segment tissues WM, GM, CSF, AD, MS, and S&M as a function of slice thickness, was analyzed using optimization parameters such as false positive ratio (FPR), false negative ratio (FNR), true positive ratio (TPR), unclassified pixel ratio (UPR) and signal-to-noise ratio (S/N). The effect of partial voluming and spatial resolution on tissue classification was also evaluated. The optimum slice thickness for six brain tissue classification was determined

Influence of Mechanical and Thermal Boundary Conditions on Stabilizing/Destabilizing Mechanisms in Evaporating Liquid Films

Liquid films, evaporating or non-evaporating, are ubiquitous in nature and technology. The dynamics of evaporating liquid films is a study applicable in several industries such as water recovery, heat exchangers, crystal growth, drug design etc. The theory describing the dynamics of liquid films crosses several fields such as engineering, mathematics, material science, biophysics and volcanology to name a few. Interfacial instabilities typically manifest by the undulation of an interface from a presumed flat state or by the onset of a secondary flow state from a primary quiescent state or both. To study the instabilities affecting liquid films, an evaporating/non-evaporating Newtonian liquid film is subject to a perturbation. Numerical analysis is conducted on configurations of such liquid films being heated on solid surfaces in order to examine the various stabilizing and destabilizing mechanisms that can cause the formation of different convective structures. These convective structures have implications towards heat transfer that occurs via this process. Certain aspects of this research topic have not received attention, as will be obvious from the literature review. Static, horizontal liquid films on solid surfaces are examined for their resistance to long wave type instabilities via linear stability analysis, method of normal modes and finite difference methods. The spatiotemporal evolution equation, available in literature, describing the time evolution of a liquid film heated on a solid surface, is utilized to analyze various stabilizing/destabilizing mechanisms affecting evaporating and non-evaporating liquid films. The impact of these mechanisms on the film stability and structure for both buoyant and non-buoyant films will be examined by the variation of mechanical and thermal boundary conditions. Films evaporating in zero gravity are studied using the evolution equation. It is found that films that are stable to long wave type instabilities in terrestrial gravity are prone to destabilization via long wave instabilities in zero gravity

Effects and management of lactobacilli in yeast-catalyzed ethanol fermentations

This thesis focuses on the effects of lactobacilli and their end-products, lactic acid and acetic acid, on 'Saccharomyces cerevisiae' growth and fermentation, and on antimicrobials used to manage such contaminants. To assess the effects of the bacteria, normal gravity (22-24 g/100 ml dissolved solids) wheat mashes inoculated with yeast at ~106 colony forming units (CFU)/ml were deliberately infected (coinoculated) with each of five industrially important strains of lactobacilli at ~10 5, ~106, ~107, ~10 8, and ~109 CFU/ml. Controls with yeast alone or with bacteria alone (~107 CFU/ml) were included. End-products, yeast growth and fermentation rates were monitored. Results indicated that production of lactic acid by lactobacilli and suspected competition of the bacteria with yeast cells for essential growth factors in the fermenting medium were the major reasons for reductions in yeast growth and decreases in final ethanol yield. A chemically defined minimal medium was used to determine the effects of added acetic and lactic acid, and their mode of action on two strains of ' S. cerevisiae'. The effects of these two acids on yeast intracellular pH (pHi), plasma membrane H+-ATPase activity and on the plasma membrane lipid composition were studied. It was found that the specific growth rates ([mu]) of the two yeast strains decreased exponentially (R2 > 0.9) as the concentrations of acetic or lactic acid were increased. Acetic and lactic acids synergistically reduced the specific growth rate of yeast. Acetic acid caused the yeast cell to expend ATP to pump out excess protons that result from the passive diffusion of the acid into the cell at medium pH (pHe) followed by its dissociation within the cell as a result of higher pHi. Lactic acid (0.5 % w/v) caused intracellular acidification (which could lead to arrest in glycolytic flux) as a result of a significant decrease (P = 0.05) in the plasma membrane H +-ATPase activity. Moreover, the plasma membrane fluidity was reduced due to decrease in unsaturated fatty acyl residues. Among the antimicrobials studied, urea hydrogen peroxide (UHP) was superior compared to stabilized chlorine dioxide and nisin, but its bactericidal activity was greatly affected by the presence of particulate matter. When used near 30 mmoles/L (in unclarified mash), in addition to its bactericidal effect, UHP provided near optimum levels of assimilable nitrogen and oxygen that aided in vigorous yeast fermentation. This process was patented

ANTI-QUORUM SENSING ACTIVITY OF SOME COMMONLY USED TRADITIONAL INDIAN SPICES

Objective: To investigate the total phenolic and flavonoids contents and study the anti-quorum sensing activity of Indian spices. Methods: The methanolic extracts of eight Indian spices were evaluated for phytochemicals and QSI (quorum sensing inhibition). QSI was determined by qualitative and quantitative violacein inhibition using Chromobacterium violaceum12472 as a reporter strain. Biofilm and inhibition of virulence factors viz. EPS (exo poly saccharide production), pyocyanin, proteolytic and swimming motility were assessed against clinically isolated Pseudomonas aeruginosa. Results: The phytochemical screening of methanolic extract of Indian spices revealed the presence of tannins, flavonoids, terpenoids, cardiac glycosides, carbohydrates, alkaloids and phenolic compounds. Among all the spices, the total phenol (35±0.53 mg/GAE/g DW) and flavonoid (18±0.22 mg/QE/g DW) contents were found to be maximum in Sygygium aromaticum. S. aromaticum exhibited highest quorum sensing(57.63±04%) and biofilm inhibition (49.36±1.5%) at 200 mg/ml. S. aromaticum also showed dose dependent inhibition of virulence factors such as EPS production, pyocyanin, proteolytic and swimming motility against clinically isolated Pseudomonas aeruginosa. ATR-IR (Attenuated total reflectance infrared) analysis of S. aromaticum extract showed phyto constituents with hydroxyl, alkynes, anhydrites, alkene, nitro compounds, aromatics, esters, sulfoxide and halogen functional groups. Conclusion: The present study promisingly revealed that S. aromaticum has an effective inhibition of biofilm caused by quorum sensing and virulence factors against clinically isolated P. aeruginosa. Biofilm prevents the entry of antibiotics, thereby developing drug resistance. The quorum quenching phyto compounds inhibit the bacterial communication and make them less virulent might be a novel non-antibiotic therapeutic system for pathogenic bacteria. Further research is necessary to identify the bioactive compound(s) responsible for the activities

Simulating charge transport to understand the spectral response of Swept Charge Devices

Context. Swept Charge Devices (SCD) are novel X-ray detectors optimized for improved spectral performance without any demand for active cooling. The Chandrayaan-1 X-ray Spectrometer (C1XS) experiment onboard the Chandrayaan-1 spacecraft used an array of SCDs to map the global surface elemental abundances on the Moon using the X-ray fluorescence (XRF) technique. The successful demonstration of SCDs in C1XS spurred an enhanced version of the spectrometer on Chandrayaan-2 using the next-generation SCD sensors. Aims. The objective of this paper is to demonstrate validation of a physical model developed to simulate X-ray photon interaction and charge transportation in a SCD. The model helps to understand and identify the origin of individual components that collectively contribute to the energy-dependent spectral response of the SCD. Furthermore, the model provides completeness to various calibration tasks, such as generating spectral response matrices (RMFs - redistribution matrix files), estimating efficiency, optimizing event selection logic, and maximizing event recovery to improve photon-collection efficiency in SCDs. Methods. Charge generation and transportation in the SCD at different layers related to channel stops, field zones, and field-free zones due to photon interaction were computed using standard drift and diffusion equations. Charge collected in the buried channel due to photon interaction in different volumes of the detector was computed by assuming a Gaussian radial profile of the charge cloud. The collected charge was processed further to simulate both diagonal clocking read-out, which is a novel design exclusive for SCDs, and event selection logic to construct the energy spectrum. Results. We compare simulation results of the SCD CCD54 with measurements obtained during the ground calibration of C1XS and clearly demonstrate that our model reproduces all the major spectral features seen in calibration data. We also describe our understanding of interactions at different layers of SCD that contribute to the observed spectrum. Using simulation results, we identify the origin of different spectral features and quantify their contributions

MICROORGANISMS VARIANTS FOR HEALTHCARE-ASSOCIATED INFECTIONS IN A SELECTED TERTIARY CARE HOSPITAL

Objective: Microorganisms are minute and can be only in microscope and these are not visible to naked eyes. Various types of microbe include bacteria, virus, fungi, and protozoa. These microorganisms are subclassified and these are disease causing leading to mortality and morbidity. Healthcare-associated infections (HAIs) arise from different variants of microbes and knowing the category of microbes for treating the diseases with specific antibiotics is important for better patient outcome. Methods: Using secondary data, all the patients who had HAI for 3 years were taken into consideration by considering the different variants of microorganisms. Results: Retrospective data collected for the period of 3 years the inpatients who got admitted for more than 48 h of duration, the data collected included the parameters for various microorganisms such as Bacilli, cocci, Klebsiella, Acinetobacter, and Aures, other micro-organisms such as Escherichia coli, Citrobacter, and Pseudomonas microorganisms. Bacilli group of microorganisms was more common for urinary tract infection, blood stream infection, and ventilator-associated pneumonia. Aures was more common among surgical site infection infections. Conclusions: Most of the patients who had an HAI had two or more different kind of microorganisms which are responsible for spreading infection. There is a need to control microbial flora in the hospital set up as the rate of HAI increases with microbial flora

Microstructure evolution in AZ61 alloy processed by Equal Channel Angular Pressing

Abstract: Magnesium and its alloys have play an strategic role in many applications like aerospace, automobile, nuclear, electrical and structural engineering due to its strength to weight ratio is very low when compared to aluminum, Titanium and steel. In the present work, AZ61 wrought magnesium alloy was processed by using Equal Channel Angular Pressing (ECAP) at three different temperatures of 483 K, 523 K and 573 K using up to four ECAP passes. A microstructural study was conducted by measuring the average grain size after each pass, for the three different processing temperatures. The mechanical properties of the processed samples were noted to improve due to the reduction in the grain size after each ECAP pass. After four ECAP passes, the average grain size of the AZ61 samples was found to be reduced to 85%, 81%, and 70% for the pressing temperatures of 483 K, 523 K and 573 K respectively. The tensile strength of the AZ61 alloy increased with increase in number of ECAP passes for each of the temperatures when compared to as-received alloy. For instances, for the processing temperature of 483 K, 523 K and 573 K, the tensile strength increased to 24%, 10%, and 12% respectively at four ECAP pass. Also, the percentage elongation of the alloy was increased with increase in processing temperatures. Moreover, fracture topographies of the tensile surfaces are illustrated through scanning electron microcopy and reveal ductile fracture than as received alloy for four passes at each ECAP processing temperature