1,029 research outputs found

    Refining Historical earthquake Data Through Modeling and Scale Model Tests

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    This study was performed for the reevaluation of historical earthquake records which occurred in Korea through tests and numerical analyses. For the scale model tests, static and cyclic lateral load tests on wooden frames that constitute a Korean ancient commoner’s house were conducted. Full-scale models of two types of frames were used for testing. Two 1:4 scale models were tested for rock and soil foundation conditions. Scaled real earthquake time histories were inputted for the tests. The peak ground acceleration (PGA) at the collapse of the house at the soil site was 0.25g, whereas PGA for moderate damage at the rock site was 0.6g. The intensity of major historical earthquake records related with house collapses was reevaluated based on the results of these scale mode1 tests. The magnitudes of historical earthquake records related with house collapses were estimated considering the magnitude, epicentral distance, soil condition and aging of the house. Eighteen artificial time histories for magnitudes 6-8, epicentral distances 5 km - 350 km and hard and soft soil condition were generated. The aging effects of the house was modeled as the lateral loading capacity of wooden frames represented by hysteretic stiffness decreased linearly with time

    Remifentanil Prevents Withdrawal Movements Caused by Intravenous Injection of Rocuronium

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    PURPOSE: The incidence of pain induced withdrawal movement following intravenous injection of rocuronium is high. This randomized, double-blind, placebo-controlled study was designed to evaluate the effect of pretreatment of remifentanil on the withdrawal movements due to intravenous injection of rocuronium during anesthetic induction. MATERIALS AND METHODS: Ninety adult female patients undergoing thyroidectomy were randomly allocated to three groups. Each patient intravenously received one of three solutions of equal volume (4 mL): normal saline (Group I, n=30), 0.5 microg/kg remifentanil (Group II, n=30) or 1 microg/kg remifentanil (Group III, n=30). Thirty seconds after remifentanil administration, anesthesia was induced with 5 mg/kg IV thiopental. Twenty seconds after thiopental injection, 0.6 mg/kg IV rocuronium was administered (injection rate of 0.5 mL/sec) and patients' withdrawal movements were assessed. Mean arterial pressure (MAP) and heart rate were assessed on arrival in the operation room, before the tracheal intubation and immediately, 1 and 2 min after the tracheal intubation. RESULTS: The incidence of withdrawal movements was significantly lower in both of the remifentanil groups (3 and 0% in Group II and III, respectively) than in the saline group (70%). Remifentanil attenuated the increase of heart rate and MAP immediately and 1 min after the tracheal intubation. CONCLUSION: The pretreatment with 0.5 and 1.0 microg/kg remifentanil of bolus doses prevented the withdrawal movements caused by rocuronium injection, and effectively blunted cardiovascular activation following tracheal intubationope

    Factors Affecting User Acceptance in Overuse of Smartphones in Mobile Health Services: An Empirical Study Testing a Modified Integrated Model in South Korea

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    Smartphones have become crucial in people's everyday lives, including in the medical field. However, as people become close to their smartphones, this leads easily to overuse. Overuse leads to fatigue due to lack of sleep, depressive symptoms, and social relationship failure, and in the case of adolescents, it hinders academic achievement. Self-control solutions are needed, and effective tools can be developed through behavioral analysis. Therefore, the aim of this study was to investigate the determinants of users' intentions to use m-Health for smartphone overuse interventions. A research model was based on TAM and UTAUT, which were modified to be applied to the case of smartphone overuse. The studied population consisted of 400 randomly selected smartphone users aged from 19 to 60 years in South Korea. Structural equation modeling was conducted between variables to test the hypotheses using a 95% confidence interval. Perceived ease of use had a very strong direct positive association with perceived usefulness, and perceived usefulness had a very strong direct positive association with behavioral intention to use. Resistance to change had a direct positive association with behavioral intention to use and, lastly, social norm had a very strong direct positive association with behavioral intention to use. The findings that perceived ease of use influenced perceived usefulness, that perceived usefulness influenced behavioral intention to use, and social norm influenced behavioral intention to use were in accordance with prior related research. Other results that were not consistent with previous research imply that these are unique behavioral findings regarding smartphone overuse. This research identifies the critical factors that need to be considered when implementing systems or solutions in the future for tackling the issue of smartphone overuse

    DRDT: Distributed and Reliable Data Transmission with Cooperative Nodes for Lossy Wireless Sensor Networks

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    Recent studies have shown that in realistic wireless sensor network environments links are extremely unreliable. To recover from corrupted packets, most routing schemes with an assumption of ideal radio environments use a retransmission mechanism, which may cause unnecessary retransmissions. Therefore, guaranteeing energy-efficient reliable data transmission is a fundamental routing issue in wireless sensor networks. However, it is not encouraged to propose a new reliable routing scheme in the sense that every existing routing scheme cannot be replaced with the new one. This paper proposes a Distributed and Reliable Data Transmission (DRDT) scheme with a goal to efficiently guarantee reliable data transmission. In particular, this is based on a pluggable modular approach so that it can be extended to existing routing schemes. DRDT offers reliable data transmission using neighbor nodes, i.e., helper nodes. A helper node is selected among the neighbor nodes of the receiver node which overhear the data packet in a distributed manner. DRDT effectively reduces the number of retransmissions by delegating the retransmission task from the sender node to the helper node that has higher link quality to the receiver node when the data packet reception fails due to the low link quality between the sender and the receiver nodes. Comprehensive simulation results show that DRDT improves end-to-end transmission cost by up to about 45% and reduces its delay by about 40% compared to existing schemes

    EFFECTS OF 10 WEEKS TRAINING PROGRAM ON LOWER EXTREMITY STRENGTH AND VERTICAL REACTION FORCE DURING SIT-TO-STAND IN CHRONIC STROKE PATIENTS

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    The purpose of this study was to investigate the effects of 10 weeks training program on lower extremity strength and' vertical reaction force during sit-to-stand movement in chronic stroke patients. Maximum vertical ground reaction force, difference of vertical ground reaction force between left and right foot, COP in anteriorposterior and mediolateral direction did not show any significant time main effect. However, the difference of body weight distribution between the left and right foot was decreased in experimental group after training. The peak torque generated by the flexors of the paretic limb at 60o /sec and 180o/sec in experimental group changed from baseline, an increases of 30.23% and 24.09%, respectively. These results appear that 10 weeks training program improves sit-to-stand movement and lower extremity strength in chronic stroke patients

    Oxygen-deficient triple perovskites as highly active and durable bifunctional electrocatalysts for oxygen electrode reactions

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    Highly active and durable bifunctional oxygen electrocatalysts have been of pivotal importance for renewable energy conversion and storage devices, such as unitized regenerative fuel cells and metal-air batteries. Perovskite-based oxygen electrocatalysts have emerged as promising nonprecious metal bifunctional electrocatalysts, yet their catalytic activity and stability still remain to be improved. We report a high-performance oxygen electrocatalyst based on a triple perovskite, Nd1.5Ba1.5CoFeMnO9-delta (NBCFM), which shows superior activity and durability for oxygen electrode reactions to single and double perovskites. When hybridized with nitrogen-doped reduced graphene oxide (N-rGO), the resulting NBCFM/N-rGO catalyst shows further boosted bifunctional oxygen electrode activity (0.698 V), which surpasses that of Pt/C (0.801 V) and Ir/C (0.769 V) catalysts and which, among the perovskite-based electrocatalysts, is the best activity reported to date. The superior catalytic performances of NBCFM could be correlated to its oxygen defect rich structure, lower charge transfer resistance, and smaller hybridization strength between O 2p and Co 3d orbitals

    Gene expression profiling of cancer stem cell in human lung adenocarcinoma A549 cells

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    <p>Abstract</p> <p>Background</p> <p>The studies on cancer-stem-cells (CSCs) have attracted so much attention in recent years as possible therapeutic implications. This study was carried out to investigate the gene expression profile of CSCs in human lung adenocarcinoma A549 cells.</p> <p>Results</p> <p>We isolated CSCs from A549 cell line of which side population (SP) phenotype revealed several stem cell properties. After staining the cell line with Hoechst 33342 dye, the SP and non-side population (non-SP) cells were sorted using flow cytometric analysis. The mRNA expression profiles were measured using an Affymetrix GeneChip<sup>® </sup>oligonucleotide array. Among the sixty one differentially expressed genes, the twelve genes inclusive three poor prognostic genes; Aldo-keto reductase family 1, member C1/C2 (AKR1C1/C2), Transmembrane 4 L six family member 1 nuclear receptor (TM4SF1), and Nuclear receptor subfamily 0, group B, member 1 (NR0B1) were significantly up-regulated in SP compared to non-SP cells.</p> <p>Conclusion</p> <p>This is the first report indicating the differences of gene expression pattern between SP and non-SP cells in A549 cells. We suggest that the up-regulations of the genes AKR1C1/C2, TM4SF1 and NR0B1 in SP of human adenocarcinoma A549 cells could be a target of poor prognosis in anti-cancer therapy.</p

    Wedging graphite into graphene and graphene-like platelets by dendritic macromolecules

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    We report in situ &apos;direct&apos; grafting of dendritic macromolecular wedges to the edges of &apos;pristine&apos; graphite. Because of the three-dimensional molecular architectures, the solubility of dendritic macromolecules is profoundly improved compared with that of their linear analogues. As a result, the resultant macromolecular wedge grafted graphite disperses well in common solvents. On the basis of results from wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM), HPEK is selectively grafted at the edges of graphite. For the efficient delamination of graphite into graphene and graphene-like platelets, the dendritic macromolecules with numerous polar periphery groups not only acts as macromolecular wedges but provides chemical affinity to solvents.close7
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