450 research outputs found
Bayesian and Frequentist Two-Sample Predictions of the Inverse Weibull Model Based on Generalized Order Statistics
2000 Mathematics Subject Classification: 62E16,62F15, 62H12, 62M20.This paper is concerned with the problem of deriving Bayesian prediction bounds for the future observations (two-sample prediction) from the inverse Weibull distribution based on generalized order statistics (GOS). Study the two side interval Bayesian prediction, point prediction under symmetric and asymmetric loss functions and the maximum likelihood (ML) prediction using "plug-in" procedure for future observations from the inverse Weibull distribution based on GOS. Study the problem of predicting future records based on observed progressive type II censored data and observed order statistics from the inverse Weibull distribution. Finally, a numerical example using real data are used to illustrate the procedure
Bayesian Prediction of Weibull Distribution Based on Fixed and Random Sample Size
2000 Mathematics Subject Classification: 62E16, 65C05, 65C20.We consider the problem of predictive interval for future observations from Weibull distribution. We consider two cases they are: (i) fixed sample size (FSS), (ii) random sample size (RSS). Further, we derive the predictive function for both FSS and RSS in closed forms. Next, the upper and lower 1%, 2.5%, 5% and 10% critical points for the predictive functions are calculated. To show the usefulness of our results, we present some simulation examples. Finally, we apply our results to some real data set in life testing given in Lawless [16]
Involvement of Oxidative Stress in Cardiovascular Diseases
Many research studies support the evidence that free radicals stress is involved in the pathogenesis of many diseases in human and animals. The current review aimed to throw the light on sources of free radicals in the cardiovascular system, involvement of oxidative stress in cardiovascular diseases and the role of the antioxidants in alleviating the damage produced by oxidative stress
The Role of Liver Biopsy in Detection of Hepatic Oxidative Stress
The goal of the current paper is to explore the role of liver biopsy as a tool in detection of hepatic oxidative stress, with brief notes on different types of free radicals, antioxidants, hepatic and blood oxidative stress, and lipid peroxidation. Hepatic oxidative stress was investigated for many years in human and animals, but most of the studies performed in animals were concerned with studying oxidative status in the liver tissues after slaughtering or euthanasia. However, in human medicine, a large number of studies were implemented to investigate the status of antioxidants in liver biopsy specimens. Similar studies are required in animals, as the changes in hepatic antioxidants and formation of lipid peroxide give a good idea about the condition of the liver. On the other hand, hepatic disease may present without significant effect on blood oxidative status, and, consequently, the best way to detect the status of hepatic oxidants and antioxidants is through measuring in liver biopsy. Measuring antioxidants status directly in the liver tissues gives an accurate estimation about the condition of the liver, permits the diagnosis of hepatic dysfunction, and helps to determine the degree of deterioration in the hepatic cells
Oxidant and Antioxidants During the Transition Period in Dairy Cows: https://doi.org/10.5281/zenodo.8224852
The transition from pregnancy to parturition is associated with metabolic and physiological changes. Oxidative stress is increased in late pregnancy and continue to be higher after parturition, which represent a challenge for the dairy cows to defend the increased free radicals by using the available antioxidants. This review discussed the process of free radical release, the development of oxidative stress and evaluation of the animal health during the transition period and threw the light on different methods used to assess oxidative stress and antioxidants therapy
Sonoelastography of the Common Flexor Tendon of the Elbow with Histologic Agreement: A Cadaveric Study.
Purpose To determine the correlation of the results of conventional B-mode ultrasonography (US) and compression sonoelastography with histologic results in common flexor tendons of the elbow in human cadavers. Materials and Methods Twenty-five common flexor tendons were evaluated in 16 fresh, unembalmed cadavers of 11 women with a median age of 85 years (range, 71-101 years) and five men with a median age of 78 years (range, 70-88 years). Informed consent was provided according to the last will of the donors. B-mode US results were classified as grade 1, normal tendon with homogeneous fibrillar pattern; grade 2, tendon thickening or hypoechoic areas and/or calcifications in less than 30% of the tendon; or grade 3, hypoechoic areas and/or calcifications greater than 30% of the tendon. Sonoelastographic results were grade 1, blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). The intraclass correlation coefficient was calculated to determine agreement with histologic findings for each B-mode US, sonoelastographic, and combined B-mode US and sonoelastographic examination. Histologic results were grade 1, normal, with parallel fibrillar pattern; grade 2, mild tendinopathy, with cellular infiltration, angiogenesis, or fatty vacuoles; or grade 3, severe tendinopathy, with loss of parallel collagen structure and necrosis. Results Histologic alterations were detected in 44% (11 of 25) of biopsy specimens. Intraclass correlation with histologic results was 0.57 for B-mode US, 0.68 for sonoelastography, and 0.84 for the combination of the two approaches. Conclusion The addition of sonoelastography to B-mode US provided statistically significant improvement in correlation with histologic results compared with the use of B-mode US alone (P \u3c .02). (©) RSNA, 2016 Online supplemental material is available for this article
Hybrid Transparent Conductive Oxide Nanostructured Materials for Photovoltaic Applications
In Ontario, there are great incentives to invest in solar cell research through the Feed-In Tariff program, which has successfully increased the total connected capacity of solar power in Ontario to well over 215 MW. Extensive studies have been conducted on fabrication of efficient solar cells, with the most mature technology being silicon-based solar cells. However, other types of solar cells have been introduced as alternatives to silicon based solar cells due to their laborious work, energy consumption, and high cost of production. Different inorganic and organic photovoltaic systems including dye-sensitized, organic/polymer, quantum-dot, and hybrid nanocrystal/polymer hetero-junctions solar cells have been proposed to provide comparable efficiencies.
Transparent conductive oxides are usually the main component in any solar system because of its role as an electrode photoanode, acting as a diffusion barrier and an open-circuit voltage attenuator. These are due to their high electrical conductivity, wide optical transmittance, and relatively ease of synthesis. As a result, a rich amount of studies on their synthesis, modification, and application as photo-catalytic electrodes, gas sensors, photonic crystals, and solar cell photoanodes exists in the literature. Their use in photovoltaics as thin film materials has since evolved into nanostructured films, as numerous studies have showed that the material morphology is an important parameter in improving solar cell performance. Many nanostructured transparent conductive oxide films have been extensively investigated for use as an n-type semiconductor in a p-n junction solar cell system or as a photoanode in a dye-sensitized solar cell (DSSC). Thus far these applications have proven challenging in terms of achieving high device efficiencies, particularly by taking advantage of their inherently higher surface area-to-volume ratio, better photon harvesting, and enhanced interparticle charge transport with shorter diffusion lengths across the device structure.
With a large direct band gap (3.37 eV), a large exciton binding energy (60 m eV), and high electron mobility (120 cm2 V-1 s-1), zinc oxide (ZnO) is considered an excellent candidate as an (n-type) transparent semiconducting material at room temperature for photovoltaic application. In the present work, two different ZnO nanostructural morphologies are prepared by controlling the electrolyte conductivity using a direct, catalyst- and seed-layer free electrodeposition method. The effect of deposition time and temperature on the growth of the high-specific-surface-area ZnO nanotubes electrodeposited is studied. Furthermore, the morphology, crystallinity, and chemical composition of the resulting ZnO nanotubes and nanorods are fully characterized with a proposed model of their growth mechanism. These one-dimensional ZnO nanostructures are then employed as an n-type semiconductor, along with a p-type Cu2O thin film, to fabricate an inorganic p-n junction solar cell. As an important step to improve device performance, the electrical and optical properties of the p-type Cu2O film are optimized by simple annealing. Two different device structures, consisting of the electrodeposited ZnO nanorods and nanotubes grown on the top of a thick n-type ZnO seed layer (500 nm) covered by an optimized (2.5µm) p-type Cu2O layer (in order to provide the full built-in potential across the junction area), are fabricated. The relations of structural morphology (i.e. nanotube vs nanorod) and characteristic solar cell parameters are investigated. The new device architecture is found to offer minimum leakage path and reduced recombination loss expected in a typical nanostructure-based solar cell. A photon-to-electron conversion efficiency (PCE) of 0.8 % is obtained for ZnO nanotubes compared to other traditional one-dimensional nanostructures (i.e. nanorods or nanowires) that is due to the increased junction area and the better charge collection. These results illustrate the advantage of single-step electrodeposition of ZnO nanotubes, which provide a larger interfacial area and a much lower defect density than previously reported nanotubes obtained by etching ZnO nanorods.
Taking advantage of their higher electron dynamics than the classical TiO2, ZnO and SnO2 are employed as photoanode materials to fabricate an organic DSSC system. To further improve the optical absorption, the effects of surface modification using gold nanoparticles to ZnO nanotubes are investigated. Different gold electrolyte concentrations are used to manipulate the plasmonic nanoparticle size while deposition time is used to control the aerial density. These studies lead to a significant increase in the PCE for DSSC based on ZnO nanotubes with gold nanoparticle modification (6%) when compared to that with pristine ZnO nanotubes (4.7%). Surface decoration with plasmonic gold nanoparticles therefore provides an efficient approach to creating not only high surface area for superior loading of dye molecules but also enhanced absorption specifically in the visible range by taking advantage of their surface plasmon resonance effect.
Hierarchical one-dimensional SnO2 nanostructures are also employed as photoanode material for DSSC application. With a band gap of 3.8 eV, low UV degradation characteristic and generally high thermal and chemical stability, SnO2 is also an excellent photoanode alternative to TiO2. Almost 10-fold enhancement of PCE (3.6%) when compared with pristine SnO2 nanobelts with (0.48%) is obtained for these hierarchical SnO2 nanostructures. This significant improvement is in part due to better dye loading of highly branched nanostructures. Additional surface passivation has also been performed on the as-deposited hierarchical SnO2 nanostructures by dip-coating with an MgO passivation layer of appropriately optimized thickness. Such an insulating layer is found to effectively reduce the recombination loss process caused by the higher electron mobility of SnO2 photoanode nanostructures. This MgO-passivation treatment further enhances the PCE to (4.14%).
The present work therefore shows that one-dimensional ZnO and SnO2 nanostructures provide a viable, powerful platform for developing the next-generation photovoltaic devices. This study further demonstrates the novel techniques used to significantly enhance the PCEs for both inorganic p-n junction solar cell and organic DSSC.4 month
Motion of Bishop Frenet Offsets of Ruled Surfaces in E
The main goal of this paper is to study the motion of two associated ruled surfaces in Euclidean 3-space E3. In particular, the motion of Bishop Frenet offsets of ruled surfaces is investigated. Additionally, the characteristic properties for such ruled surfaces are given. Finally, an application is presented and plotted using computer aided geometric design
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