110 research outputs found

    The impact of Arctic sea ice loss on mid-Holocene climate.

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    Mid-Holocene climate was characterized by strong summer solar heating that decreased Arctic sea ice cover. Motivated by recent studies identifying Arctic sea ice loss as a key driver of future climate change, we separate the influences of Arctic sea ice loss on mid-Holocene climate. By performing idealized climate model perturbation experiments, we show that Arctic sea ice loss causes zonally asymmetric surface temperature responses especially in winter: sea ice loss warms North America and the North Pacific, which would otherwise be much colder due to weaker winter insolation. In contrast, over East Asia, sea ice loss slightly decreases the temperature in early winter. These temperature responses are associated with the weakening of mid-high latitude westerlies and polar stratospheric warming. Sea ice loss also weakens the Atlantic meridional overturning circulation, although this weakening signal diminishes after 150-200 years of model integration. These results suggest that mid-Holocene climate changes should be interpreted in terms of both Arctic sea ice cover and insolation forcing

    Vision-Inspection System for Residue Monitoring of Ready-Mixed Concrete Trucks

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    The objective of this study is to propose a vision-inspection system that improves the quality management for ready-mixed concrete (RMC). The proposed system can serve as an alternative to the current visual inspection method for the detection of residues in agitator drum of RMC truck. To propose the system, concept development and the system-level design should be executed. The design considerations of the system are derived from the hardware properties of RMC truck and the conditions of RMC factory, and then 6 major components of the system are selected in the stage of system level design. The prototype of system was applied to a real RMC plant and tested for verification of its utility and efficiency. It is expected that the proposed system can be employed as a practical means to increase the efficiency of quality management for RMC

    Quantitative Analysis of Aortic Atherosclerosis in Korean Female: A Necropsy Study

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    To assess the regional difference and influence of the biological variables on atherosclerosis in female, we analyzed 7 segments of aorta (2 ascending, 3 thoracic, and 2 abdominal) from 90 superficially healthy Korean women (39±14 yr of age) who died from external causes. Tissue specimens were macroscopically examined and histopathologically divided into 7 grades for scoring (ATHERO, from 0=intact, to 6=thrombi formation). Lumen diameter (LD), wall thickness (WT), intima thickness (INT), and media thickness (MED) were obtained by computed morphometry. Atherosclerosis was common in the distal infrarenal (C2), proximal thoracic (B1), and proximal ascending (A1) segments. Total 95.6% of all subjects had atherosclerosis of variable degree in one or more segments, but an aneurysmal change was not found. The number of atherosclerotic segments and atherosclerosis score in the 7 segments increased with aging. However, the body size did not affect the aortic size and ATHERO. With aging, LD and INT of the A1, B1 and C2 increased (p<.00001); WT of the B1 and C2 increased (p<.01); and MED of C2 decreased (p<.01). LD and WT of the B1 and C2 (p<.05), INT of the A1, B1 and C2 (p<.00001) increased, and MED of C2 decreased (p<.01) with ATHERO. These data suggest that age is simple but a reliable parameter for estimating the progression of atherosclerosis

    Prophylactic Hypogastric Artery Ballooning in a Patient with Complete Placenta Previa and Increta

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    Abnormal attachment of the placenta (Placenta accreta, increta, and percreta) is an uncommon but potentially lethal cause of maternal mortality from massive postpartum hemorrhage. A 33-yr-old woman, who had been diagnosed with a placenta previa, was referred at 30 weeks gestation. On ultrasound, a complete type of placenta previa and multiple intraplacental lacunae, suggestive of placenta accreta, were noted. For further evaluation of the placenta, pelvis MRI was performed and revealed findings suspicious of a placenta increta. An elective cesarean delivery and subsequent hysterectomy were planned for the patient at 38 weeks gestation. On the day of delivery, endovascular catheters for balloon occlusion were placed within the hypogastric arteries, prior to the cesarean section. In the operating room, immediately after the delivery of the baby, bilateral hypogastric arteries were occluded by inflation of the balloons in the catheters previously placed within. With the placenta retained within the uterus, a total hysterectomy was performed in the usual fashion. The occluding balloons were deflated after closure of the vaginal cuff with hemostasis. The patient had stable vital signs and normal laboratory findings during the recovery period; she was discharged six days after delivery without complications. The final pathology confirmed a placenta increta

    Rapid access to polycyclic N-heteroarenes from unactivated, simple azines via a base-promoted Minisci-type annulation

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    Conventional synthetic methods to yield polycyclic heteroarenes have largely relied on metal-mediated arylation reactions requiring pre-functionalised substrates. However, the functionalisation of unactivated azines has been restricted because of their intrinsic low reactivity. Herein, we report a transition-metal-free, radical relay pi-extension approach to produce N-doped polycyclic aromatic compounds directly from simple azines and cyclic iodonium salts. Mechanistic and electron paramagnetic resonance studies provide evidence for the in situ generation of organic electron donors, while chemical trapping and electrochemical experiments implicate an iodanyl radical intermediate serving as a formal biaryl radical equivalent. This intermediate, formed by one-electron reduction of the cyclic iodonium salt, acts as the key intermediate driving the Minisci-type arylation reaction. The synthetic utility of this radical-based annulative pi-extension method is highlighted by the preparation of an N-doped heptacyclic nanographene fragment through fourfold C-H arylation. The functionalisation of unactivated azines has been restricted because of their intrinsic low reactivity. Here the authors show a transition-metal-free, radical relay pi-extension approach to produce N-doped polycyclic aromatic compounds directly from simple azines and cyclic iodonium salts

    The expression and localization of inhibin isotypes in mouse testis during postnatal development

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    Inhibin, which is important for normal gonadal function, acts on the pituitary gonadotropins to suppress follicle-stimulating hormone (FSH) secretion. The level and cellular localization of the inhibin isotypes, α, βA and βB, in the testis of mice were examined during postnatal development in order to determine if inhibin expression is related to testicular maturation. Mouse testes were sampled on postnatal days (PNDs) 1, 3, 6, 18, 48 and 120, and analyzed by Western blotting and immunofluorescence. Western blot analysis showed very low levels of inhibin α, βA and βB expression in the testes at days 1 to 6 after birth. The levels then increased gradually from PND 18 to 48-120, and there were significant peaks at PND 48. Inhibin α, βA and βB were detected in testicular cells during postnatal development using immunohistochemistry. The immunoreactivity of inhibin α was rarely observed in testicular cells during PND 1 to 6, or in the cytoplasmic process of Sertoli cells surrounding the germ cells and interstitial cells during PND 18 to 120. Inhibin βA and βB immunoreactivity was rarely observed in the testis from PND 1 to 6. On the other hand, it was observed in some spermatogonial cells, as well as in the interstitial space between PND 48 and PND 120. We conclude that the expression of inhibin isotypes increases progressively in the testis of mice with increasing postnatal age, suggesting that inhibin is associated with a negative feedback signal for FSH in testicular maturation
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