Numerical Simulations of Some Real-Life Problems Governed by ODEs

In this chapter, some real-life model problems that can be formulated as ordinary differential equations (ODEs) are introduced and numerically studied. These models are the variable-order fractional Hodgkin–Huxley model of neuronal excitation (VOFHHM) and other models with the variable-order fractional (VOF) time delay, such as the 4-year life cycle of a population of lemmings model, the enzyme kinetics with an inhibitor molecule model, and the Chen system model. A class of numerical methods is used to study the above-mentioned models such as non-standard finite difference (NSFD) and Adams-Bashforth-Moulton (ABM) methods. Numerical test examples are presented

Test-taking Strategies on Reading Comprehension Tests: A Review of Major Research Themes

There is a growing body of thought and research on strategy use on tests of reading comprehension. Nevertheless, there have been few research reviews that have treated major themes involved in thought and research on test-taking strategies, specifically in the context of reading comprehension. Hence, this paper reviews the themes that are central to the discussion of strategy choice and use on reading comprehension tests. Research themes that form the foci of the paper include discussion of test-taking strategies as they relate to the process of reading test-taking, formats of reading tests, validation of reading tests, level of language proficiency, and performance on tests of reading comprehension

A clinical and ultrastructural investigation of the cornea in keratoconus

Keratoconus is a non-inflammatory corneal disease that progressively causes topographical alteration of the cornea as a result of thinning, and consequently leads to impaired vision. In this thesis, the clinical studies are showed that the incidence rate and severity of keratoconus in Asir province, Saudi Arabia is high with an early onset and more rapid progress to the severe disease stage at a young age compared to other countries. The result also showed that the disease required different contact lens designs to be available in the clinics and the selection of initial back optic zone radius for multiple contact lens designs should be based in the steepest keratometric reading in early stage, and on average keratometric reading on moderate and advanced stages. However, regardless of the stage of disease, tricurve contact lens design should be selected based on average keratometric reading. Ultrastructure investigation of the anterior surface of Bowman's layer using different microscopes revealed that the changes are not limited to the apical cone only, but extend to the periphery of the cornea especially in the advances stage of keratoconus. Also, although the topographical map is usually used in trephination, it was found that the topographical features alone failed to indicate the full extent of the progress of keratoconus towards the corneal periphery. Data from transmission electron microscopy and high-angle X-ray diffraction suggest that the structural abnormalities in the stromal fibrillar matrix might be influential underlying reasons for topographic changes in the keratoconic-like changes of SPARC-null and JKC mice.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Fungal dysbiosis predicts the diagnosis of pediatric Crohn's disease

AIM: To investigate the accuracy of fungal dysbiosis in mucosa and stool for predicting the diagnosis of Crohn’s disease (CD). METHODS: Children were prospectively enrolled in two medical centers: one university hospital and one private gastroenterology clinic in the city of Riyadh, Kingdom of Saudi Arabia. The children with confirmed diagnosis of CD by standard guidelines were considered cases, and the others were considered non-inflammatory bowel disease controls. Mucosal and stool samples were sequenced utilizing Illumina MiSeq chemistry following the manufacturer’s protocols, and abundance and diversity of fungal taxa in mucosa and stool were analyzed. Sparse logistic regression was used to predict the diagnosis of CD. The accuracy of the classifier was tested by computing the receiver operating characteristic curves with 5-fold stratified cross-validation under 100 permutations of the training data partition and the mean area under the curve (AUC) was calculated. RESULTS: All the children were Saudi nationals. There were 15 children with CD and 20 controls. The mean age was 13.9 (range: 6.7-17.8) years for CD children and 13.9 (3.25-18.6) years for controls, and 10/15 (67%) of the CD and 13/20 (65%) of the control subjects were boys. CD locations at diagnosis were ileal (L1) in 4 and colonic (L3) in 11 children, while CD behavior was non-stricturing and non-penetrating (B1) in 12 and stricturing (B2) in 3 children. The mean AUC for the fungal dysbiosis classifier was significantly higher in stools (AUC = 0.85 ± 0.057) than in mucosa (AUC = 0.71 ± 0.067) (P < 0.001). Most fungal species were significantly more depleted in stools than mucosal samples, except for Saccharomyces cerevisiae and S. bayanus, which were significantly more abundant. Diversity was significantly more reduced in stools than in mucosa. CONCLUSION: We found high AUC of fungal dysbiosis in fecal samples of children with CD, suggesting high accuracy in predicting diagnosis of CD. Key Words: Fungiome, Mycobiome, Crohn’s disease, Inflammation, Saudi children Core tip: We found high accuracy of fungal dysbiosis in predicting diagnosis of Crohn’s disease (CD), a finding similar to bacterial dysbiosis. However, the higher area under the curve for the fungal dysbiosis classifier in stool (0.85 ± 0.057) than in mucosa (0.71 ± 0.067) (P < 0.001), contrasts with bacterial studies, suggesting higher accuracy of stool samples. Although the clinical application of this finding is limited at present by the high cost of fungal analysis, such information is important from a scientific viewpoint, to increase the understanding of the role of fungal flora in CD and to stimulate further studies.The authors extend their appreciations to the Deanship of Scientific Research at King Saud University in Riyadh, Kingdom of Saudi Arabia for funding this work through Research Group No [RGP-1436-007]. This work was also supported by a grant from the Simons Foundation [No. 409704] to Kirill Korolev) and by the startup fund from Boston University to Kirill Korolev. Simulations were carried out on Shared Computing Cluster at Boston University. Rajita Menon was partially supported by a Hariri Graduate Fellowship from Boston University. Harland Winter, MD received support from Martin Schlaff and the Diane and Dorothy Brooks Foundation. (RGP-1436-007 - King Saud University in Riyadh, Kingdom of Saudi Arabia; 409704 - Simons Foundation; Boston University; Hariri Graduate Fellowship from Boston University; Diane and Dorothy Brooks Foundation)Published versio

Effect of stabilizer on optical band gap of ZnO and their performance in dye-sensitized solar cells

ABSTRACT. In dye-sensitized solar cells, transparent metal oxide working electrodes play a vital role in defining the power conversion efficiency. It was found that the size of nanoparticles influences the electrical, optical properties of these electrodes. Herein, we describe the synthesis of ZnO with zinc acetate dihydrate and different stabilizers (diethylamine and triethylamine) by using a modified solvothermal process. The obtained materials were characterized by XRD, SEM, EDX, TEM, HRTEM, UV-visible, FTIR, and Raman methods. The crystallite sizes for ZnO-1 and ZnO-2 samples were indexed as 39.0 and 40.5 nm for the highest peak intensity with diethylamine and triethylamine stabilizer, respectively. We examine the effect of stabilizers on the morphology, optical band gap, and photovoltaic performance of the prepared ZnO. We found that ZnO prepared using diethylamine stabilizer exhibiting significant efficiency of 1.45%, open-circuit voltage 0.454 V, short-circuit current density 2.128 mA/cm2, and 0.66 fill factor were achieved under 44 mW/cm2 illumination powers with dye-3. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; KEY WORDS: Dye-sensitized solar cells, ZnO, Band gap, Photovoltaic performance &nbsp; Bull. Chem. Soc. Ethiop. 2022, 36(1), 209-222.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; DOI: https://dx.doi.org/10.4314/bcse.v36i1.17 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp

Antécédents culturaux et identification de quelques pratiques paysannes en replantation cacaoyère en Côte d'Ivoire

La Côte d’Ivoire est le premier producteur mondial de cacao, avec plus de 1700 000 tonnes. Cette performance a été atteinte, principalement, par l’accroissement des superficies cultivées aux dépends de la forêt. L’enquête a concerné les parcelles de cacaoyers de moins de 5 ans (0-5 ans) et chaque producteur a été enquêté individuellement, chacun sur sa parcelle, afin de confronter les réponses aux observations de terrain. Les résultats des enquêtes effectuées, entre 2002 et 2003, par le projet PIC-CACAO, montrent que trois types d’antécédents culturaux sont actuellement utilisés pour la culture du cacaoyer en Côte d’Ivoire. Il s’agit des vieilles cacaoyères, des vieilles caféières et des jachères, moins favorables à la culture du cacaoyer. Face aux contraintes rencontrées au cours du renouvellement du verger cacaoyer sur ces antécédents, les producteurs ont, soit adopté des techniques proposées par la recherche, soit adapté certaines de leurs pratiques endogènes aux nouvelles conditions écologiques et naturelles du milieu. Les adoptions ont concernés l’utilisation de matériel végétal amélioré, issu des pépinières, sur les jachères. Quant aux adaptations, elles se sont traduites par la pratique de fortes densités de plantation de jeunes cacaoyers et par la densification de l’ombrage.Mots clés: Cacaoyer, antécédents culturaux, adoptions, adaptations, Côte d’IvoireEnglish Title: Cropping history and identification of some farmer pratices in cocoa replanting in Côte d’IvoireEnglish AbstractCôte d’Ivoire is the first producer of cocoa worldwide with more than 1700 000 tons. This performance was reached, mainly, by the increase of acreages at the expense of the forest. The investigation concerned the cocoa plots under 5 years (0-5 years) and each producer was investigated individually, each on his plot in order to compare his responses with field observations. The results of the investigations carried out, between 2002 and 2003, by PIC-cacao project, show that three types of antecedents are currently used for the culture of the cocoa-tree. They are the old cocoa plantations, the old coffee plantations and the fallow, less favourable of the cultivation of cocoa. Faced with the constraints during the renewal of the cocoaorchard on these antecedents, producers adopted techniques proposed by research or adapted some endogenous practices to the new ecological and natural conditions of the environment. The adoptions related to the use of vegetable material improved and nurseries on the fallow. As for the adaptations, they resulted in the use of high densities of plantation of young cocoa-trees and to the thickening of the shade.Keywords: Cocoa-orchard (Theobroma cacao L.), farming antecedents, adoptions, adaptations, Côte d’Ivoir

Nanocrystalline Na0.1V2O5.nH2Oxerogel Thin Film for Gas Sensing

Nanocrystalline thin film of Na0.1V2O5.nH2O xerogel obtained by sol-gel synthesis was used as a gas sensor. Gas sensing properties of different gases such as hydrogen, petroleum and humidity were investigated. Applying XRD and TEM the size of the nanocrystals is found to be 7.5 nm. SEM shows a highly porous structure with submicron meter-sized voids present throughout the sample. FTIR measurement shows different chemical groups identifying the obtained series of gels. The sample was n-type semiconductor according to the thermoelectric power and electrical conductivity. It can be seen that the sensor response curves from 130°C to 150°C show a rapid increase in sensitivity for all types of gas injection, low response values for heating period and the rapid high response values for cooling period. This result may suggest that this material is able to act as gas sensor during the heating and cooling process

Nanocrystalline Na0.1V2O5.nH2Oxerogel Thin Film for Gas Sensing

Nanocrystalline thin film of Na0.1V2O5.nH2O xerogel obtained by sol-gel synthesis was used as a gas sensor. Gas sensing properties of different gases such as hydrogen, petroleum and humidity were investigated. Applying XRD and TEM the size of the nanocrystals is found to be 7.5 nm. SEM shows a highly porous structure with submicron meter-sized voids present throughout the sample. FTIR measurement shows different chemical groups identifying the obtained series of gels. The sample was n-type semiconductor according to the thermoelectric power and electrical conductivity. It can be seen that the sensor response curves from 130°C to 150°C show a rapid increase in sensitivity for all types of gas injection, low response values for heating period and the rapid high response values for cooling period. This result may suggest that this material is able to act as gas sensor during the heating and cooling process

Diagnostic importance of platelet parameters in patients with acute coronary syndrome admitted to a tertiary care hospital in southwest region, Saudi Arabia

AbstractObjectiveIdentifying risk factors for acute coronary syndrome (ACS) is important for both diagnostic and prognostic purposes. Abnormal platelet parameters, mainly platelet count (PC), mean platelet volume (MPV) and platelet distribution width (PDW) are thought to be among these risk factors. In this study, the associations between PC, MPV and PDW and ACS were investigated in patients admitted to the tertiary care hospital in the south west region of Saudi Arabia.Materials and methodsA retrospective cohort of 212 patients with the diagnosis of ACS admitted to Aseer Central Hospital during the period extending from February 1, 2008 to October 31, 2008 were included. The control group consisted of 49 matched subjects who were admitted for chest pain investigation and subsequently found to be non-cardiac chest pain after performing relevant investigations. Blood samples were taken at the time of admission for platelet parameters. Statistical analysis was made using SPSS software and P-values were considered significant if <0.05.ResultsA total of 212 patients with acute coronary syndrome (80 patients with MI and 132 patients with UA) and 49 matched controls were studied. The PC was not statistically different among the three groups (283.3±94.8×109L−1 for MI cases, 262±60.8×109L−1 for UA cases and 275.8±58.9×109L−1 for controls). The MPV was significantly larger in MI cases compared to controls (8.99±1.5fl vs. 8.38±0.51fl, respectively, P<0.009), similarly, the MPV was significantly larger in UA cases compared to controls (9.23±1.19fl vs. 8.38±0.51fl, respectively, P<0.001). The PDW was significantly higher in MI cases compared to controls (15.88±1.5fl vs. 11.96±1.8fl, respectively, P<0.001), similarly, the PDW as also significantly larger in UA cases compared to controls (18.1±18fl vs. 11.96±1.8fl, respectively, P<0.019).ConclusionPlatelet parameters mainly MPV and PDW are readily available and relatively simple and inexpensive laboratory tests which we detected to be significantly raised in patients who have suffered an acute coronary syndrome compared with controls

Efficacy of self-designed intraoral appliances in prevention of cheek, lip and tongue bite after local anesthesia administration in pediatric patients

The occurrence of self-inflicted soft tissue injuries following administration of local anesthesia in pediatric patients who have received dental treatment has been reported. Aim: To evaluate the attitudes and knowledge regarding cheek, lip, and tongue bite post administration of local anesthesia among dental practitioners in Saudi Arabia. Additionally, the efficacies of three types of intraoral appliances on the prevention of self-harm were evaluated in pediatric patients. A total of 301 practitioners were provided with a questionnaire consisting of 9 items. In addition, three types of intraoral appliances made of polyethylene terephthalate were designed as follows: design 1 (consisted of an anterior extension with numerous perforations); design 2 (had a buccal flap extension); and design 3 (comprised of serrated borders). The appliances were placed in the oral cavities of 45 children (age, 3?15 years) immediately after the completion of the dental procedure. The patient was asked to retain the appliance for 3 h. After 24 h, both parents and children were required to respond to a checklist to evaluate the effectiveness the appliances. Almost half of the dental practitioners had never encountered self-inflicted soft tissue injury in children after local anesthesia administration. About 60% of the dentists were of the opinion that provision of adequate instructions after treatment could prevent the occurrence of lip, cheek, and tongue biting. Furthermore, among the three appliances used, design 1 was most well accepted. Intraoral appliances used in this study may be considered for use to prevent self-inflicted soft tissue trauma in children following administration of local anesthesia