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151.
152.
Ju Hwan Kim Kyung Hwun Chung Yeong Ran Hwang Hye Ran Park Hee Jung Kim Hyung-Gun Kim Hak Rim Kim 《International journal of molecular sciences》2021,22(10)
Exposure to radiofrequency electromagnetic fields (RF-EMFs) has increased rapidly in children, but information on the effects of RF-EMF exposure to the central nervous system in children is limited. In this study, pups and dams were exposed to whole-body RF-EMF at 4.0 W/kg specific absorption rate (SAR) for 5 h per day for 4 weeks (from postnatal day (P) 1 to P28). The effects of RF-EMF exposure on neurons were evaluated by using both pups’ hippocampus and primary cultured hippocampal neurons. The total number of dendritic spines showed statistically significant decreases in the dentate gyrus (DG) but was not altered in the cornu ammonis (CA1) in hippocampal neurons. In particular, the number of mushroom-type dendritic spines showed statistically significant decreases in the CA1 and DG. The expression of glutamate receptors was decreased in mushroom-type dendritic spines in the CA1 and DG of hippocampal neurons following RF-EMF exposure. The expression of brain-derived neurotrophic factor (BDNF) in the CA1 and DG was significantly lower statistically in RF-EMF-exposed mice. The number of post-synaptic density protein 95 (PSD95) puncta gradually increased over time but was significantly decreased statistically at days in vitro (DIV) 5, 7, and 9 following RF-EMF exposure. Decreased BDNF expression was restricted to the soma and was not observed in neurites of hippocampal neurons following RF-EMF exposure. The length of neurite outgrowth and number of branches showed statistically significant decreases, but no changes in the soma size of hippocampal neurons were observed. Further, the memory index showed statistically significant decreases in RF-EMF-exposed mice, suggesting that decreased synaptic density following RF-EMF exposure at early developmental stages may affect memory function. Collectively, these data suggest that hindered neuronal outgrowth following RF-EMF exposure may decrease overall synaptic density during early neurite development of hippocampal neurons. 相似文献
153.
Minjoong Rim 《Wireless Personal Communications》2012,64(4):619-623
One way to mitigate interference in Orthogonal Frequency Division Multiplexing systems is to use a reduced number of subcarriers
instead of full resources. Assuming there is no information on the positions of used subcarriers of interferers, this paper
discusses the optimal number of used subcarriers to maximize the system performance. If the noise level is negligible compared
to the interference amount, the number of used subcarriers needs to be decreased inversely proportional to the number of users. 相似文献
154.
Sahbi Ouertani Ahmed Koubaa Soufien Azzouz Rim Bahar Lamine Hassini Ali Belghith 《Holz als Roh- und Werkstoff》2018,76(4):1101-1111
The aims of this study were to determine (1) the effects of microwave irradiation on the drying kinetics of jack pine wood, (2) the phytosanitary efficacy, and (3) the processing energy consumption and mechanical strength of the dried product. Microwave drying experiments were performed at 2.45 GHz frequency and at microwave powers ranging from 300 to 1000 W. Results indicate that higher microwave power and initial wood temperature and lower sample thickness increases the internal sample temperature, improves the drying rate, and reduces both drying time and energy consumption. The microwave irradiation efficacy to sanitize jack pine wood boards was determined in terms of temperature/time combinations based on actual drying kinetics according to standards for phytosanitary measures. The energy required to dry 12 mm thick wood board samples at microwave power ranging from 300 to 1000 W was in the range of 36.4–12.3 MJ/kg of water, respectively, for up to 65% energy consumption savings. The impact of microwave power on the mechanical properties was not statistically significant, although mechanical properties tended to decrease with increasing power. 相似文献
155.
The paper presents a new review of parallel Kalman filtering for nonlinear channel equalization. A Network of Extended Kalman Filters (nekf) has already been suggested for this purpose. This equalizer gives recursively a minimum mean squared error (mmse) estimation of a sequence of transmitted symbols according to a state formulation of a digital communication scheme. It is essentially based on two mechanisms: the approximation of the non Gaussiana posteriori probability density function (pdf) of the symbol sequence by a Weighted Gaussian Sum (wgs); and the local linearization of the nonlinear channel function for each branch of the network. Since the linearization, bearing on scattered symbol states, is one of the major limitations of thenekf, a new Kalman filtering approach, the Unscented Kalman Filter (ukf) suggested by Julier and Uhlman is considered in this paper for an interesting adaptation to the equalization context. Theukf algorithm is based on the equations of a Kalman filter, as the optimal linear minimum variance estimator, and on determining conditional expectations based on a kind of deterministic Monte-Carlo simulations. The new equalizer referred to as the Network ofukf (nukf), thus combines density approximation by awgs and the Unscented Transformation (ut) principle to circumvent the linearization brought within eachekf and is shown to perform better than thenekf based equalizer for severe nonlinear channels. Also, an adaptive version of thenukf is developed using the k-means clustering algorithm for noise-free channel output identification, since thenukf-based algorithm does not require the knowledge of the channel nonlinearity model. 相似文献
156.
Minkyoung Sung Soo-Eun Sung Kyung-Ku Kang Joo-Hee Choi Sijoon Lee KilSoo Kim Ju-Hyeon Lim Gun Woo Lee Hyo-Deog Rim Byung-Soo Kim Seunghee Won Kyungmin Kim Seoyoung Jang Min-Soo Seo Jungmin Woo 《International journal of molecular sciences》2021,22(18)
Stress is the physical and psychological tension felt by an individual while adapting to difficult situations. Stress is known to alter the expression of stress hormones and cause neuroinflammation in the brain. In this study, miRNAs in serum-derived neuronal exosomes (nEVs) were analyzed to determine whether differentially expressed miRNAs could be used as biomarkers of acute stress. Specifically, acute severe stress was induced in Sprague-Dawley rats via electric foot-shock treatment. In this acute severe-stress model, time-dependent changes in the expression levels of stress hormones and neuroinflammation-related markers were analyzed. In addition, nEVs were isolated from the serum of control mice and stressed mice at various time points to determine when brain damage was most prominent; this was found to be 7 days after foot shock. Next-generation sequencing was performed to compare neuronal exosomal miRNA at day 7 with the neuronal exosomal miRNA of the control group. From this analysis, 13 upregulated and 11 downregulated miRNAs were detected. These results show that specific miRNAs are differentially expressed in nEVs from an acute severe-stress animal model. Thus, this study provides novel insights into potential stress-related biomarkers. 相似文献
157.
In Sung Song Soo Won Heo Jun Hee Lee Jung Rim Haw Doo Kyung Moon 《Journal of Industrial and Engineering Chemistry》2012,18(1):312-316
A polymer light emitting diodes (PLEDs) was fabricated using the wet processable antimony tin oxide (ATO) as the transparent electrode by spin coating method. PLED were fabricated with ATO (or ITO)/PEDOT:PSS/polymer/BaF2/Ba/Al configurations. Electrical and optical properties of ATO transparent electrode were measured. Transmittance of ATO thin film was more than 90% in the visible region, sheet resistance was 30 Ω/□ and had a strong solvent resistance. The maximum brightness and maximum efficiency of PLED device using an ATO transparent electrode was 3637 cd/m2 and 1.03 cd/A, respectively. 相似文献
158.
159.
Ragnarsson L.-A. Guha S. Bojarczuk N.A. Cartier E. Fischetti M.V. Rim K. Karasinski J. 《Electron Device Letters, IEEE》2001,22(10):490-492
High-effective mobilities are demonstrated in Al2O3 based n-channel MOSFETs with Al gates. The Al2O3 was grown in ultra-high vacuum using a reactive atomic beam deposition system. The mobility with maximum values at approximately 270 cm2/Vs, is found to approach that of SiO 2 based MOSFETs at higher fields 相似文献
160.
“How Negative Becomes Less Negative”: Understanding the Effects of Comment Valence and Response Sidedness in Social Media 下载免费PDF全文
This study explores the influence of the public's negative comments regarding a corporate social responsibility (CSR) campaign in social media and how to best respond to them. It examined the interaction effects of comment valence and the company's response sidedness on the public's attitudes as mediated by the perceived negativity and perceived altruism. Results revealed that 2‐sided CSR responses are more effective than 1‐sided responses in enhancing altruistic motives for CSR, reducing perceived negativity in the public's comments, and eliciting favorable attitudes, especially when comments were negative. The effects of message sidedness disappeared when the public's comments were positive. Results also showed that perceived altruism and negativity mediate the effects of message strategies on the public's attitudes toward the company. 相似文献