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철분 결핍성 빈혈이 어린이의 인지도 및 신경계 발달에 끼치는 영향
Walter, Thomas 대한영양사협회 1999 대한영양사협회 학술지 Vol.5 No.2
When iron deficiency anemia ensues during the first 2 years of life it has been associated with delayed psychomotor development and changes in behavior. These effects have been shown to persist after several months of iron therapy, despite complete correction of iron nutritional measures. Moreover, it is still uncertain whether or to what extent they are reversible after a extended period of observation, since the long term prospective follow-up studies reported to date, show the persistence of cognitive deficits at 5~6 and at 10 years of age in those who during infancy had anemia. The inherent difficulties of identifying intervening variables in the complex field of mental development, coupled in some cases with suboptimal design have prevented significant progress in the investigation of iron deficiency. However, two studies, one conducted in Costa Rica (Lozoff et al, 1987) and the other in Santiago, Chile (Walter, et al 1989), taking into careful consideration the potential pitfalls confirm conclusions arising from previous work. The Santiago study was performed in association with a field trial of fortified infant foods. One hundred ninety-six healthy, full-term infants were assessed with the Bayley scales of infant development(Bayley, 1969) at 12, 121/2 and 15 months of age. The Costa Rica study enrolled 191 12 to 23 month-old otherwise healthy infants with diverse iron status. The infants were divided into groups ranging from most to least iron deficient.
Walter W Chan,Hiroshi Mashimo 대한소화기 기능성질환∙운동학회 2013 Journal of Neurogastroenterology and Motility (JNM Vol.19 No.3
Background/Aims Lubiprostone, a chloride channel type 2 (ClC-2) activator, was thought to treat constipation by enhancing intestinal secretion. It has been associated with increased intestinal transit and delayed gastric emptying. Structurally similar to prostones with up to 54% prostaglandin E2 activity on prostaglandin E receptor 1 (EP1), lubiprostone may also exert EP1-mediated procontractile effect on intestinal smooth muscles. We investigated lubiprostone’s effects on intestinal smooth muscle contractions and pyloric sphincter tone. Methods Isolated murine small intestinal (longitudinal and circular) and pyloric tissues were mounted in organ baths with modified Krebs solution for isometric recording. Basal muscle tension and response to electrical field stimulation (EFS; 2 ms pulses/10 V/6 Hz/30 sec train) were measured with lubiprostone (10-10-10-5 M) ± EP1 antagonist. Significance was established using Student t test and P < 0.05. Results Lubiprostone had no effect on the basal tension or EFS-induced contractions of longitudinal muscles. With circular muscles, lubiprostone caused a dose-dependent increase in EFS-induced contractions (2.11 ± 0.88 to 4.43 ± 1.38 N/g, P = 0.020) that was inhibited by pretreatment with EP1 antagonist (1.69 ± 0.70 vs. 4.43 ± 1.38 N/g, P = 0.030). Lubiprostone had no effect on circular muscle basal tension, but it induced a dose-dependent increase in pyloric basal tone (1.07 ± 0.01 to 1.97 ± 0.86 fold increase, P < 0.05) that was inhibited by EP1 antagonist. Conclusions In mice, lubiprostone caused a dose-dependent and EP1-mediated increase in contractility of circular but not longitudinal small intestinal smooth muscles, and in basal tone of the pylorus. These findings suggest another mechanism for lubiprostone’s observed clinical effects on gastrointestinal motility.
Structural response of composite concrete filled plastic tubes in compression
Walter O. Oyawa,Naftary K. Gathimba,Geoffrey N. Mang’uriu 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3
Kenya has recently experienced worrying collapse of buildings during construction largely attributable to the poor quality of in-situ concrete and poor workmanship. The situation in the country is further compounded by rapid deterioration of infrastructure, hence necessitating the development of alternative structural systems such as concrete filled unplasticized poly vinyl chloride (UPVC) tubes as columns. The work herein adds on to the very limited and scanty work on use of UPVC tubes in construction. This study presents the findings of experimental and analytical work which investigated the structural response of composite concrete filled UPVC tubes under compressive load regime. UPVC pipes are cheaper than steel tubes and can be used as formwork during construction and thereafter as an integral part of column. Key variables in this study included the strength of infill concrete, the length to diameter ratio (L/D) of the plastic tube, as well as the diameter to thickness ratio (D/2t) of the plastic tube. Plastic tubes having varying diameters and heights were used to confine concrete of different strengths. Results obtained in the study clearly demonstrate the effectiveness of UPVC tubes as a confining medium for infill concrete, attributable to enhanced composite interaction between the UPVC tube and infill concrete medium. It was determined that compressive strength of the composite column specimens increased with increased concrete strength while the same decreased with increased column height, albeit by a small margin since all the columns considered were short columns. Most importantly, the experimental confined concrete strength increased significantly when compared to unconfined concrete strength; the strength increased between 1.18 to 3.65 times the unconfined strength. It was noted that lower strength infill concrete had the highest confined strength possibly due to enhanced composite interaction with the confining UPVC tube. The study further proposes an analytical model for the determination of confined strength of concrete.
Walters, K. The Korean Society of Rheology 1999 Korea-Australia rheology journal Vol.11 No.4
The main events in the historical development of Rheology are traced and particular attention is paid to the leading players, the controversies, the priority disputes and the nomenclature disagreements. Some of the lessons to be learned from the past are then highlighted and a positive assessment is given of the prospects for rheological research in the next millennium