3,070 research outputs found

    Chronic rhinosinusitis with nasal polyps in older adults : clinical presentation, pathophysiology, and comorbidity

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    Purpose of Review Chronic rhinosinusitis and nasal polyps (CRSwNP) is a common condition that significantly affects patients' life. This work aims to provide an up-to-date overview of CRSwNP in older adults, focusing on its aging-related clinical presentations, pathophysiology, and comorbidity associations including asthma. Recent Findings Recent large population-based studies using nasal endoscopy have shown that CRSwNP is a mostly late-onset disease. Age-related changes in physiologic functions, including nasal epithelial barrier dysfunction, may underlie the incidence and different clinical presentations of CRSwNP in older adults. However, there is still a paucity of evidence on the effect of aging on phenotypes and endotypes of CRSwNP. Meanwhile, late-onset asthma is a major comorbid condition in patients with CRSwNP; they frequently present with type 2 inflammatory signatures that are refractory to conventional treatments when they are comorbid. However, as they are more commonly non-atopic, causative factors other than classical atopic sensitization, such as Staphylococcus aureus specific IgE sensitization, are suggested to drive the type 2 inflammation. There are additional comorbidity associations in older patients with CRSwNP, including those with chronic otitis media and head and neck malignancy. Age is a major determinant for the incidence and clinical presentations of CRSwNP. Given the heterogeneity in phenotypes and endotypes, longitudinal investigations are warranted to elucidate the effects of aging on CRSwNP

    Hull-form optimization of a 66,000 dwt bulk carrier in irregular wave condition

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    This paper deploys optimization techniques to obtain the optimum hull form of a 66,000 DWT bulk carrier in calm water and in irregular head waves at sea state 6. Parametric modification functions for the bow hull-form variation are SAC shape, section shape (U-V type, DLWL type). Multi-objective functions are applied to minimize the values of wave-making resistance in calm water and mean added resistance in waves. WAVIS version 1.3 is used to obtain wave-making resistance in calm water condition. The modified Fujii and Takahashi's formula is applied to obtain the added resistance in short waves. The added resistance in long wave is obtained from the potential-flow solver based on the 3-D panel method. And the mean added resistance in irregular head waves is obtained by linear superposition of the wave spectrum and the response function. The PSO (Particle swarm optimization) algorithm is employed for the optimization technique. The resistance and motion characteristics in calm water, in regular head waves and in irregular head waves of the two hull forms are compared. It has been shown that the optimal brings 6.8% reduction in the mean added resistance at sea state 6

    The Effect of Feedback Types on Academic Achievement in Learning with Computerized Tests

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    An earlier version of this article was presented at the Pacific Rim Objective Measurement Symposium (PROMS 2006), The Hong Kong Institute of Education, Tai Po, Hong Kong, June 27th-29th, 2006The purpose of this study was to show the effect of back types (standardized type vs. differentiated type) on academic achievement in learning with computerized tests. For this study, two computerized learning programs with different feedback types were developed with HTML, PHP, and SQL computer languages, and a science achievement test was developed by two high school science teachers. The science achievement tests content and face validity were examined by 5 high school science teachers and its Cronbach's alpha coefficient was 0.82. The research subjects were 137 10th graders from 4 classrooms within 2 high schools in Korea. They were divided into two groups. One group took a 3-weeks learning program with computerized a test using standardized type feedbacks. The other group also took a 3-week learning program with a computerized test using differentiated type feedbacks. After learning with computerized tests was implemented, a science achievement test was administered to all students belonging to both groups. The result of data analysis with ANCOVA was that differentiated type feedback was more effective than the standardized type feedback for learning with computerized test (F=8.98, p<0.01)

    Experimental Study on Coordinated Heading Control of Four Vessels Moored Side by Side

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    A floating type liquefied natural gas (LNG) bunkering terminal has been under development in Korea since 2014; the terminal is designed to receive LNG from an LNG carrier (LNGC) and transfer it to two other LNG bunkering shuttles (LNGBS) simultaneously. The operational feasibility of the LNG loading and unloading processes has been confirmed. When four vessels are moored side by side with mooring ropes and fenders, their positions must be maintained within the designed allowable criteria. In addition, the floating bunkering terminal (FLBT) has its own mooring system, an internal turret with catenary mooring lines and stern tunnel thrusters to maintain its own position and control the vessel heading. In this study, we investigated the operational feasibility of the FLBT during the LNG loading and unloading operations with four vessel mooring configurations and heading controls. A series of model tests was done in the ocean engineering basin of the Korea Research Institute of Ships and Ocean engineering. The motion responses of the four vessels were determined using an optical measurement system, and the tensile loads on ship-to-ship mooring ropes and the compressive loads on ship-to-ship fenders were measured using one-axis load cells. A white noise test was done and the results were compared with the numerical results for the purpose of validation. Then, four combined environmental conditions were presented both without heading control and with several heading control cases. Finally, we determined the available safe bunkering heading ranges taking into account the tensile loads on the mooring ropes

    Thermoelectric properties of graphene incorporated thermoelectric materials

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    Thermoelectric materials, which can change the waste heat into the usable electricity, are interested in various field of applications such as vehicle, ship, power plane, and so on. To enhance the thermoelectric properties, high electrical conductivity, high Seebeck coefficient, and low thermal conductivity should be conducted, however, the trade-off relation between electronic property and thermal property in terms of carrier concentration could be the bottle-neck on the enhancement of thermoelectric properties of the materials. In this presentation, we discuss with the graphene incorporation in the conventional thermoelectric materials, which could lead to independently control electric and thermal properties

    Point Mutation of Hoxd12 in Mice

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    Purpose: Genes of the HoxD cluster play a major role in vertebrate limb development, and changes that modify the Hoxd12 locus affect other genes also, suggesting that HoxD function is coordinated by a control mechanism involving multiple genes during limb morphogenesis. In this study, mutant phenotypes were produced by treatment of mice with chemical mutagen, N-ethyl-N-nitrosourea (ENU). We analyzed mutant mice exhibiting the specific microdactyly phenotype and examined the genes affected. Materials and Methods: We focused on phenotype characteristics including size, bone formation, and digit morphology of ENU-induced microdactyly mice. The expressions of several molecules were analyzed by genome-wide screening and quantitative real-time PCR to define the affected genes. Results: We report on limb phenotypes of an ENU-induced A-to-C mutation in the Hoxd12 gene, resulting in alanine-to-serine conversion. Microdactyly mice exhibited growth defects in the zeugopod and autopod, shortening of digits, a missing tip of digit I, limb growth affected, and dramatic increases in the expressions of Fgf4 and Lmx1b. However, the expression level of Shh was not changed Hoxd12 point mutated mice. Conclusion: These results suggest that point mutation rather than the entire deletion of Hoxd12, such as in knockout and transgenic mice, causes the abnormal limb phenotype in microdactyly mice. The precise nature of the spectrum of differences requires further investigation.link_to_subscribed_fulltex

    The role of Pd-Pt Interactions in the Oxidation and Sulfur Resistance of Bimetallic Pd-Pt/γ-Al2O3Diesel Oxidation Catalysts

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    Diesel oxidation catalysts (DOC) were investigated for oxidation activity, NO conversion stability, and sulfur poisoning/regeneration on Pd/Al2O3, Pt/Al2O3, and Pd-Pt/Al2O3 catalysts. The Pd/Al2O3 catalyst was more active for CO and hydrocarbon (C3H6 and C3H8) oxidation, while the Pt/Al2O3 catalyst efficiently oxidized NO. The formation of a Pd-Pt alloy in the Pd-Pt/Al2O3 catalyst maintained Pd in a more reduced phase, resulting in the superior activity of this catalyst for the oxidation of CO, C3H6, and NO in comparison with its monometallic counterparts. The Pd-Pt alloy not only provided more low-temperature activity but also retained the stability of NO oxidation. The Pd-Pt alloy also favored the spillover of SO2 to the alumina support, resulting in significantly higher adsorption capacity of the Pd-Pt/Al2O3 catalyst, extensively prolonging its lifetime. However, the stable sulfates on Pd-Pt/Al2O3 made it difficult to completely regenerate the catalyst. The bimetallic sample showed higher activity for CO, C3H8, and C3H6 after sulfur poisoning and regeneration
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