Numerical Modeling of Turbulent Combustion

The work in numerical modeling is focused on the use of the random vortex method to treat turbulent flow fields associated with combustion while flame fronts are considered as interfaces between reactants and products, propagating with the flow and at the same time advancing in the direction normal to themselves at a prescribed burning speed. The latter is associated with the generation of specific volume (the flame front acting, in effect, as the locus of volumetric sources) to account for the expansion of the flow field due to the exothermicity of the combustion process. The model was applied to the flow in a channel equipped with a rearward facing step. The results obtained revealed the mechanism of the formation of large scale turbulent structure in the wake of the step, while it showed the flame to stabilize on the outer edges of these eddies

Modeling Interface Motion Of Combustion (MINOC). A computer code for two-dimensional, unsteady turbulent combustion

A computer code for calculating the flow field and flame propagation in a turbulent combustion tunnel is described. The model used in the analysis is the random vortex model, which allows the turbulent field to evolve as a fundamental solution to the Navier-Stokes equations without averaging or closure modeling. The program was used to study the flow field in a model combustor, formed by a rearward-facing step in a channel, in terms of the vorticity field, the turbulent shear stresses, the flame contours, and the concentration field. Results for the vorticity field reveal the formation of large-scale eddy structures in the turbulent flow downstream from the step. The concentration field contours indicate that most burning occurred around the outer edges of the large eddies of the shear layer

The impact of image dynamic range on texture classification of brain white matter

<p>Abstract</p> <p>Background</p> <p>The Greylevel Cooccurrence Matrix method (COM) is one of the most promising methods used in Texture Analysis of Magnetic Resonance Images. This method provides statistical information about the spatial distribution of greylevels in the image which can be used for classification of different tissue regions. Optimizing the size and complexity of the COM has the potential to enhance the reliability of Texture Analysis results. In this paper we investigate the effect of matrix size and calculation approach on the ability of COM to discriminate between peritumoral white matter and other white matter regions.</p> <p>Method</p> <p>MR images were obtained from patients with histologically confirmed brain glioblastoma using MRI at 3-T giving isotropic resolution of 1 mm³. Three Regions of Interest (ROI) were outlined in visually normal white matter on three image slices based on relative distance from the tumor: one peritumoral white matter region and two distant white matter regions on both hemispheres. Volumes of Interest (VOI) were composed from the three slices. Two different calculation approaches for COM were used: i) Classical approach (CCOM) on each individual ROI, and ii) Three Dimensional approach (3DCOM) calculated on VOIs. For, each calculation approach five dynamic ranges (number of greylevels N) were investigated (N = 16, 32, 64, 128, and 256).</p> <p>Results</p> <p>Classification showed that peritumoral white matter always represents a homogenous class, separate from other white matter, regardless of the value of N or the calculation approach used. The best test measures (sensitivity and specificity) for average CCOM were obtained for N = 128. These measures were also optimal for 3DCOM with N = 128, which additionally showed a balanced tradeoff between the measures.</p> <p>Conclusion</p> <p>We conclude that the dynamic range used for COM calculation significantly influences the classification results for identical samples. In order to obtain more reliable classification results with COM, the dynamic range must be optimized to avoid too small or sparse matrices. Larger dynamic ranges for COM calculations do not necessarily give better texture results; they might increase the computation costs and limit the method performance.</p

Biochemical Parameters in Obese Egyptian Patients as a Non-Invasive Marker for Disease Screening in Early Diagnosis of Non-Alcoholic Fatty Liver Disease

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) has recently been considered as the most public liver problem worldwide and a major clinicopathologic health burden in the developed countries. Biochemical tests are important in verifying a better understanding of many diseases and hence help to have the right decisions for achieving better management. AIM: This study was conducted to assess biochemical markers in NAFLD Egyptian patients. METHODS: Forty obese subjects (32 females and 8 males, mean age was 42.32 ± 9.12 years) (20 with NAFLD and 20 without NAFLD) and 20 normal participants were selected. RESULTS: Body mass index (BMI) was 40.86 ± 5.45 in obese FL versus 22.07 ± 2.10 in control, p &lt; 0.001 and versus 35.83 ± 5.94 in obese non-FL, p = 0.003. Alanine aminotransferase (ALT) was 57.30 ± 46.24 in obese FL versus 25.45 ± 7.12 in control, p = 0.003 and versus 27.35 ± 11.09 in obese non-FL, p = 0.005. Aspartate aminotransferase (AST) (41.40 ± 36.09 in obese FL vs. 21.7 ± 3.81 in control, p = 0.015 and vs. 24.05 ± 7.50 in obese non-FL, p = 0.032). Total bilirubin (T.Bil) (0.62 ± 0.25 in obese FL vs. 0.47 ± 0.15 in control, p = 0.014). Prothrombin time (PT) (86.80 ± 11.32 in obese FL vs. 97.86 ± 4.31 in control, p &lt; 0.001) and International Normalization Ratio (INR) (1.11 ± 0.13 in obese FL vs. 1.01 ± 0.02 in control, p = 0.002). Triglycerides (TGs) (128.20 ± 43.49 in obese FL vs. 88.35 ± 24.26 in control, p &lt; 0.001 and vs. 94.50 ± 31.65 in obese non-FL, p = 0.003). Ferritin (88.21 ± 54.88 in obese FL vs. 47.65 ± 32.07 in obese non-FL, p = 0.006). Alpha-fetoprotein (AFP) (2.42 ± 1.67 in obese FL vs. 1.20 ± 0.75 in control, p = 0.001). Fasting blood sugar (FBS) (119.70 ± 49.11 in obese FL vs. 84.10 ± 7.19 in control, p &lt; 0.001 and vs. 80.50 ± 8.84 in obese non-FL, p &lt; 0.001) and postprandial (P.P) (152.80 ± 82.86 in obese FL vs. 94.35 ± 3.70 in control, p &lt; 0.001 and vs. 93.35 ± 7.77 in obese non-FL, p &lt; 0.001). Serum high-density lipoprotein (HDL) level was significantly lower in NAFLD patients compared to obese non-FL (40.05 ± 5.81 vs. 41.9 ± 4.85, p &lt; 0.001). CONCLUSION: NAFLD is associated with changes in biochemical parameters. Its early assessment can help in modifying the disease course and delaying complications

Optimizing automated characterization of liver fibrosis histological images by investigating color spaces at different resolutions

Texture analysis (TA) of histological images has recently received attention as an automated method of characterizing liver fibrosis. The colored staining methods used to identify different tissue components reveal various patterns that contribute in different ways to the digital texture of the image. A histological digital image can be represented with various color spaces. The approximation processes of pixel values that are carried out while converting between different color spaces can affect image texture and subsequently could influence the performance of TA. Conventional TA is carried out on grey scale images, which are a luminance approximation to the original RGB (Red, Green, and Blue) space. Currently, grey scale is considered sufficient for characterization of fibrosis but this may not be the case for sophisticated assessment of fibrosis or when resolution conditions vary. This paper investigates the accuracy of TA results on three color spaces, conventional grey scale, RGB, and Hue-Saturation-Intensity (HSI), at different resolutions. The results demonstrate that RGB is the most accurate in texture classification of liver images, producing better results, most notably at low resolution. Furthermore, the green channel, which is dominated by collagen fiber deposition, appears to provide most of the features for characterizing fibrosis images. The HSI space demonstrated a high percentage error for the majority of texture methods at all resolutions, suggesting that this space is insufficient for fibrosis characterization. The grey scale space produced good results at high resolution; however, errors increased as resolution decreased

Texture analysis of MR images of patients with Mild Traumatic Brain Injury

<p>Abstract</p> <p>Background</p> <p>Our objective was to study the effect of trauma on texture features in cerebral tissue in mild traumatic brain injury (MTBI). Our hypothesis was that a mild trauma may cause microstructural changes, which are not necessarily perceptible by visual inspection but could be detected with texture analysis (TA).</p> <p>Methods</p> <p>We imaged 42 MTBI patients by using 1.5 T MRI within three weeks of onset of trauma. TA was performed on the area of mesencephalon, cerebral white matter at the levels of mesencephalon, corona radiata and centrum semiovale and in different segments of corpus callosum (CC) which have been found to be sensitive to damage. The same procedure was carried out on a control group of ten healthy volunteers. Patients' TA data was compared with the TA results of the control group comparing the amount of statistically significantly differing TA parameters between the left and right sides of the cerebral tissue and comparing the most discriminative parameters.</p> <p>Results</p> <p>There were statistically significant differences especially in several co-occurrence and run-length matrix based parameters between left and right side in the area of mesencephalon, in cerebral white matter at the level of corona radiata and in the segments of CC in patients. Considerably less difference was observed in the healthy controls.</p> <p>Conclusions</p> <p>TA revealed significant changes in texture parameters of cerebral tissue between hemispheres and CC segments in TBI patients. TA may serve as a novel additional tool for detecting the conventionally invisible changes in cerebral tissue in MTBI and help the clinicians to make an early diagnosis.</p

Synthesis of 2-[(4-amino or 2,4-diaminophenyl)sulfonyl] derivatives of benzimidazole, benzothiazole and 6-methyluracil as potential antimicrobial agents

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Emerging Anthelmintic Resistance in Poultry: Can ethnopharmacological approaches offer a solution?

Limited pharmacological studies have been conducted on plant species used against poultry helminths. The objective of this study was to provide a basis for plant based anthelmintics as possible alternatives against poultry anthelmintic resistance. The study justified the need for alternative anthelmintics. The study places emphasis on the increasing anthelmintic resistance, mechanism of resistance, and preparational protocols for plant anthelmintics and their associated mechanism of action. Pharmaceutical studies on plants as alternative therapies for the control of helminth parasites have not been fully explored especially in several developing countries. Plants from a broad range of species produce a wide variety of compounds that are potential anthelmintics candidates. Important phenolic acids have been found in Brassica rapa L. and Terminalia avicenniodes Guill. and Perri that affect the cell signaling pathways and gene expression. Benzo (c) phenanthridine and isoquinoline alkaloids are neurotoxic to helminths. Steroidal saponins (polyphyllin D and dioscin) interact with helminthic mitochondrial activity, alter cell membrane permeability, vacuolation and membrane damage. Benzyl isothiocyanate glucosinolates interfere with DNA replication and protein expression, while isoflavones from Acacia oxyphylla cause helminth flaccid paralysis, inhibit energy generation, and affect calcium utilization. Condensed tannins have been shown to cause the death of nematodes and paralysis leading to expulsion from the gastro-intestinal tract. Flavonoids from Chenopodium album L and Mangifera indica L act through the action of phosphodiesterase and Ca(2+)-ATPase, and flavonoids and tannins have been shown to act synergistically and are complementary to praziquantel. Artemisinins from Artemisia cina O. Berg are known to disrupt mitochondrial ATP production. Terpenoids from Cucurbita moschata L disrupt neurotransmission leading to paralysis as well as disruption of egg hatching. Yeast particle encapsulated terpenes are effective for the control of albendazole-resistant helminths