Статті в журналах: "Doubly spread channels"

1

Zeng, Wen-Jun, and Xue Jiang. "Time reversal communication over doubly spread channels." Journal of the Acoustical Society of America 132, no. 5 (November 2012): 3200–3212. http://dx.doi.org/10.1121/1.4754524.

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2

Eggen, Trym H., and James C. Preisig. "Underwater acoustic communication over doubly spread channels." Journal of the Acoustical Society of America 101, no. 5 (May 1997): 3157. http://dx.doi.org/10.1121/1.419090.

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3

Zeng, Wen-Jun, and Xue Jiang. "Time reversal communication over doubly spread channels." Journal of the Acoustical Society of America 134, no. 5 (November 2013): 4033. http://dx.doi.org/10.1121/1.4830726.

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4

Zhang, Yang, Qunfei Zhang, Chengbing He, and Chao Long. "Channel estimation for OTFS system over doubly spread sparse acoustic channels." China Communications 20, no. 1 (January 2023): 50–65. http://dx.doi.org/10.23919/jcc.2023.01.005.

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5

Zeng, Wen-Jun, and Wen Xu. "Fast estimation of sparse doubly spread acoustic channels." Journal of the Acoustical Society of America 131, no. 1 (January 2012): 303–17. http://dx.doi.org/10.1121/1.3665992.

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6

Drumheller, David Mark, and Dennis W. Ricker. "Receiver-transmitter optimization for detection in doubly spread channels." Journal of the Acoustical Society of America 89, no. 4 (April 1991): 1714–23. http://dx.doi.org/10.1121/1.401005.

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7

Li, Jie, Fangjiong Chen, Songzuo Liu, Hua Yu, and Fei Ji. "Estimation of Overspread Underwater Acoustic Channel Based on Low-Rank Matrix Recovery." Sensors 19, no. 22 (November 15, 2019): 4976. http://dx.doi.org/10.3390/s19224976.

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In this paper, the estimation of overspread, i.e., doubly spread underwater acoustic (UWA) channels of strong dispersion is considered. We show that although the UWA channel dispersion causes the degeneration of channel sparsity, it leads to a low-rank structure especially when the channel delay-Doppler-spread function is separable in delay and Doppler domain. Therefore, we introduce the low-rank criterion to estimate the UWA channels, which can help to improve the estimation performance in the case of strong dispersion. The estimator is based on the discrete delay-Doppler-spread function representation of channel, and is formulated as a low-rank matrix recovery problem which can be solved by the singular value projection technique. Simulation examples are carried out to demonstrate the effectiveness of the proposed low-rank-based channel estimator.

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8

McDonald, Vincent K., Richard C. Shockley, Joseph A. Rice, and Dale Green. "Probe signals for obtaining impulse response of doubly‐spread channels." Journal of the Acoustical Society of America 102, no. 5 (November 1997): 3118. http://dx.doi.org/10.1121/1.420575.

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9

Bhadouria, Vijay Singh, Monika Agrawal, and Ritesh Kumar. "An unsupervised clustering-based scale-lag receiver design approach for the doubly selective underwater acoustic channel." Journal of the Acoustical Society of America 152, no. 1 (July 2022): 342–53. http://dx.doi.org/10.1121/10.0012349.

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This paper details the architecture of a novel scale-lag rake receiver for the doubly selective underwater acoustic (UWA) channel. The shallow UWA channel is known to have a large Doppler spread. The cause of this is primarily due to the large spread of the angle of arrival of the received signal's paths. The Doppler scale value is dependent on the angle of arrival of the received signal. The Doppler spread is significant, and multiple Doppler scales are present in the UWA channel. Therefore, the receivers operating with only a single Doppler scale compensation perform sub-optimally. The optimal receiver should incorporate all possible Doppler scales for better performance. The receiver needs to have multiple sampling rates to incorporate all Doppler scales. It is usually done by having multiple receive channels, one for each sampling rate. It requires tremendous resources as its complexity increases exuberantly. This paper shows that these Doppler scales are clustered and that an optimal receiver is implemented using fewer receiver channels, each corresponding to one such cluster. It reduces the receiver's complexity. The simulation results demonstrate that using the Doppler scale value associated with the path of the highest magnitude per cluster yields the best performance.

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10

Zeng, Wen-Jun, and Wen Xu. "Low complexity estimation and equalization of doubly spread underwater acoustic channels." Journal of the Acoustical Society of America 131, no. 4 (April 2012): 3275. http://dx.doi.org/10.1121/1.4708244.

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11

Edelson, Geoffrey S., and Luca Cazzanti. "Differential frequency hopping performance in doubly spread underwater acoustic communication channels." Journal of the Acoustical Society of America 140, no. 4 (October 2016): 3230. http://dx.doi.org/10.1121/1.4970209.

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12

Qu, Fengzhong, Xingyang Nie, and Wen Xu. "A Two-Stage Approach for the Estimation of Doubly Spread Acoustic Channels." IEEE Journal of Oceanic Engineering 40, no. 1 (January 2015): 131–43. http://dx.doi.org/10.1109/joe.2014.2307194.

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13

Acklin, Susan E. "Electrical Properties and Anion Permeability of Doubly Rectifying Junctions in the Leech Central Nervous System." Journal of Experimental Biology 137, no. 1 (July 1, 1988): 1–11. http://dx.doi.org/10.1242/jeb.137.1.1.

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A study has been made of the electrical connections between touch sensory (T) neurones in the leech central nervous system (CNS) which display remarkable double rectification: depolarization spreads in both directions although hyperpolarization spreads poorly. Tests were made to determine whether this double rectification was a property of the junctions themselves or whether it resulted from changes in the length constants of processes intervening between the cell body and the junctions. Following trains of action potentials, T cells and their fine processes within the neuropile became hyperpolarized through the activity of an electrogenie sodium pump. When any T cell was hyperpolarized by 25 mV by repetitive stimulation, hyperpolarization failed to spread to the T cells to which it was electrically coupled. Further evidence for double rectification of junctions linking T cells was provided by experiments in which Cl− was injected electrophoretically. Cl− injection into one T cell caused inhibitory potentials recorded in it to become reversed. After a delay, Cl− spread to reverse IPSPs in the coupled T cell. Movement of Cl−, like current flow, was dependent on membrane potential. When the T cell into which Cl− was injected was kept hyperpolarized, Cl− failed to move into the adjacent T cell. Upon release of the hyperpolarization in the injected T cell, Cl− moved and reversed IPSPs in the coupled T cell. Together these results indicate that the gating properties of channels linking T cells are voltage-dependent, such that depolarization of either cell allows channels to open whereas hyperpolarization causes them to close.

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14

Ebihara, Tadashi, and Koichi Mizutani. "Underwater Acoustic Communication With an Orthogonal Signal Division Multiplexing Scheme in Doubly Spread Channels." IEEE Journal of Oceanic Engineering 39, no. 1 (January 2014): 47–58. http://dx.doi.org/10.1109/joe.2013.2245273.

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15

Zhang, Xing, Kang Song, Chunguo Li, and Luxi Yang. "A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform." Applied Sciences 8, no. 1 (January 1, 2018): 38. http://dx.doi.org/10.3390/app8010038.

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16

Zhao, Xiaochuan, Tao Peng, Ming Yang, and Wenbo Wang. "Doppler Spread Estimation by Tracking the Delay-Subspace for OFDM Systems in Doubly Selective Fading Channels." IEEE Signal Processing Letters 16, no. 3 (March 2009): 212–15. http://dx.doi.org/10.1109/lsp.2008.2010812.

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17

Laraway, Stephen Andrew, and Behrouz Farhang-Boroujeny. "Performance Analysis of a Multicarrier Spread Spectrum System in Doubly Dispersive Channels With Emphasis on HF Communications." IEEE Open Journal of the Communications Society 1 (2020): 462–76. http://dx.doi.org/10.1109/ojcoms.2020.2986323.

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18

Gass, J. H., D. L. Noneaker, and M. B. Pursley. "A comparison of slow-frequency-hop and direct-sequence spread-spectrum packet communications over doubly selective fading channels." IEEE Transactions on Communications 50, no. 8 (August 2002): 1236–39. http://dx.doi.org/10.1109/tcomm.2002.801459.

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19

Fan, Wei Wei, Lu Liu, You Wen Zhang, Ji Gang Dong, and Da Jun Sun. "An MMSE Approach to Channel Shorting for Underwater Acoustic FH-FSK Communication." Applied Mechanics and Materials 511-512 (February 2014): 334–41. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.334.

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Underwater acoustic channel is the biggest obstacle which causes the underwater acoustic communication falling behind the wireless communication. Generally speaking, underwater acoustic channel will represent doubly spread, i.e. multipath spread and Doppler spread. Also the multipath spread will be quite long in the underwater acoustic channel. For example, the multipath spread will be several milliseconds in the shallow sea and several seconds in the deep sea. Multipath spread will lead to Inter-Symbol Interference (ISI), and Doppler spread will cause the channel to be rapidly time-varying. Although ISI can be suppressed by channel equalizer, but because of the long multipath spread, it increases the complexity about the design of the equalizer. In this paper, channel shortening will be used to reduce the ISI. We present two methods of channel shorting, which are Time Reversal (TR) filter and the Minimum Mean Squared Error (MMSE) filter. When the two filters are used in FH-FSK, we found that the performance of MMSE filter is better than TR filter. Taking into account the characteristics of sparse underwater acoustic channel, Compressive Sensing (CS) algorithm is used for channel estimation. Finally, We perform a series of numerical simulations and the experiments on the lake to show that MMSE filter outperformances the TR filter under the FH-FSK system using the bit error rate (BER) as an evaluation criterion.

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20

Sun, Dajun, Jie Wu, Xiaoping Hong, Changxin Liu, Hongyu Cui, and Boyu Si. "Iterative double-differential direct-sequence spread spectrum reception in underwater acoustic channel with time-varying Doppler shifts." Journal of the Acoustical Society of America 153, no. 2 (February 2023): 1027–41. http://dx.doi.org/10.1121/10.0017116.

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Conventional double differential phase-shift keying modulation amplifies the phase noise and performs poorly under the time-varying direct-sequence spread-spectrum (DSSS) communication system. Therefore, the authors propose an iterative reception for DSSS communication in time-varying underwater acoustic channels. First, bit-interleaved coded modulation with iterative decoding integrated with multi-symbol differential detection is used. Second, this paper uses cross correlation method to estimate and track the Doppler shift of each symbol. Based on Doppler estimates, a dynamic linear prediction model is proposed to estimate and track the channel phase variation. Third, an algorithm for adaptive selection of reference signals is utilized to recover the magnitude attenuation of correlation peaks. Numerical simulation results demonstrate that the proposed reception achieves around 9 dB gain compared to conventional differential decision reception under constant acceleration of 0.14 [Formula: see text]. During the acoustic communication experiment in Songhua Lake, the proposed reception was tested by using a moving source at a speed of 1–6 knots at 2-m depth and the farthest distance between the transceivers is 2.8 km. The proposed reception achieves only one frame error from a total of 205 frames collected in the lake experiment, and it also achieves error-free communications over 96 frames during a 10 km depth deep-sea experiment.

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21

Lazaropoulos, Athanasios G. "Broadband Transmission and Statistical Performance Properties of Overhead High-Voltage Transmission Networks." Journal of Computer Networks and Communications 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/875632.

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This paper considers broadband signal transmission and statistical performance properties of high-voltage/broadband over power lines (HV/BPL) channels associated with overhead power transmission. The overhead HV/BPL transmission channel is investigated with regard to its spectral behavior, its end-to-end signal attenuation, and its statistical performance metrics. It is found that the above features depend critically on the frequency, the overhead HV power grid type (150 kV, 275 kV, or 400 kV and single- or double-circuit), the coupling scheme applied, the physical properties of the cables used, the MTL configuration, and the type of branches existing along the end-to-end BPL signal propagation. The contribution of this paper is threefold. First, the significant broadband transmission potential of overhead HV lines is revealed. The results demonstrate that, regardless of overhead HV power grid type, the overhead HV grid is a potentially excellent communications medium, offering low-loss characteristics, flat-fading features, and low multipath dispersion over a 25 km repeater span well beyond 100 MHz. Second, regarding the statistical properties of various overhead HV/BPL transmission channels, two fundamental correlations of several wireline systems, for example, coaxial cables and xDSL, are also validated in the case of overhead HV/BPL transmission channels, namely, (i) end-to-end channel attenuation in relation with root-mean-square delay spread (RMS-DS) and (ii) coherence bandwidth (CB) in relation with RMS-DS. Third, fitting the numerical results and other field trial measurements, two regression distributions suitable for each fundamental correlation are proposed.

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22

Sui, Tao, Yongxin Feng, Bo Qian, Fang Liu, Qiang Jiang, and Xiao Li. "Design and Analysis of a Multi−Carrier Orthogonal Double Bit Rate Differential Chaotic Shift Keying Communication System." Electronics 12, no. 8 (April 10, 2023): 1785. http://dx.doi.org/10.3390/electronics12081785.

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A new multi−carrier orthogonal double bit rate differential chaotic shift keying (MC−ODBR−DCSK) communication system is presented in this paper. With two composite signals generated by an orthogonal chaotic signal generator as reference signals, 2M bits of information data are transmitted on M−channel subcarriers, improving transmission speed and energy efficiency. In addition, the receiver does not require a radio frequency (RF) delay circuit to demodulate the received data, which makes the system easier to implement. This paper analyzes Data−energy−to−Bit−energy Ratio (DBR) of the system. The bit error rate performance of the system is simulated to verify the impact of parameters such as chaotic maps, semi-spread spectrum factor, and sub-carrier number. At the same time, the bit error rate performance of the MC−ODBR−DCSK system is compared with traditional DCSK systems in Rician fading and additive Gaussian white noise (AWGN) channels.

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23

LEE, JunHwan, Tomoaki OHTSUKI, and Masao NAKAGAWA. "Turbo Equalized Double Window Cancellation and Combining Robust to Large Delay Spread Channel." IEICE Transactions on Communications E92-B, no. 2 (2009): 517–26. http://dx.doi.org/10.1587/transcom.e92.b.517.

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24

Sun, Zeng You, and Xia Ling. "Time-Varying Channel Multi-Carrier Modulation Technology Research." Applied Mechanics and Materials 513-517 (February 2014): 2680–86. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.2680.

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With frequency selective fading from multi-path characteristic and time selective fading from high speed mobility, double selective channel has become the typical context for the current wireless communication system. To realize high performance transmission in time-varying channel, this paper presents DAFT-OFDM multicarrier modulation scheme. The simulation results show that the scheme is applicable to time-varying fading channel, in which each path experiences independent Doppler spread. The scheme can also reduce ICI effectively.

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25

LEE, J., Y. KISHIYAMA, T. OHTSUKI, and M. NAKAGAWA. "Double Window Cancellation and Combining for OFDM in Time-Invariant Large Delay Spread Channel." IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E90-A, no. 10 (October 1, 2007): 2066–78. http://dx.doi.org/10.1093/ietfec/e90-a.10.2066.

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26

Noneaker, D. L., and M. B. Pursley. "Selection of spreading sequences for direct-sequence spread-spectrum communications over a doubly selective fading channel." IEEE Transactions on Communications 42, no. 12 (1994): 3171–77. http://dx.doi.org/10.1109/26.339838.

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27

Chow, Lun. "Spread of smoke and heat along narrow air cavity in double-skin façade fires." Thermal Science 18, suppl.2 (2014): 405–16. http://dx.doi.org/10.2298/tsci110918094c.

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A scenario on double-skin fa?ade fire was identified earlier for hazard assessment. A flashover room fire occurred next to the fa?ade, broke the interior glass pane and spread to the fa?ade cavity. As observed in experiments, hot gas moved up as a vertical channel flow for narrow fa?ade cavity. Heat and smoke spread along the narrow air cavity of a double-skin fa?ade will be studied in this paper. A simple mathematical model is developed from basic heat transfer theory for studying the vertical air temperature profiles of the hot gas flowing along the cavity. Assuming one-dimensional flow for hot gas moving up the fa?ade cavity, conservation equations on mass and enthalpy were solved. Experimental results on two double-skin fa?ade rigs of height 6 m and 15 m with narrow cavity depth were used to justify the results. A total of 11 tests were carried out. Correlation expressions between cavity air temperature and the height above ceiling of the fire room were derived.

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28

Abenov, R. R., E. V. Rogozhnikov, Ya V. Kryukov, D. A. Pokamestov, and P. A. Abenova. "Experimental Study of a Transmission System Based on FBMC/OQAM." Journal of the Russian Universities. Radioelectronics 24, no. 6 (December 29, 2021): 16–26. http://dx.doi.org/10.32603/1993-8985-2021-24-6-16-26.

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Introduction. This paper investigates a transmission system based on FBMC/OQAM multiplexing. This system is characterized by a high spectral efficiency, thereby attracting interest as an alternative transmission method in future wireless mobile communication standards. However, a disadvantage of the system is the high complexity of signal processing. There are numerous publications that study the FBMC/OQAM system from a theoretical perspective. This paper presents an experimental study of a transmission system based on FBMC/OQAM.Aim. Verification of a transmission system based on FBMC/OQAM multiplexing in a wireless channel.Materials and methods. Computer simulation modeling in Matlab and experimental research using Keysight and Rohde & Schwarz certified measuring instruments.Results. A model of synthesis and signal processing was developed, and a frame structure was proposed. The processing included synchronization, since the study was carried out in a wireless double-dispersive channel. Time synchronization was provided by the method of time-domain correlation. A preamble consisting of two symbols was used for CFO compensation. Channel estimation in FBMC/OQAM was conducted by pilot symbols spread over the time-frequency domain, a method with an auxiliary pilot to compensate for intrinsic interference, as well as Zero Forcing and a linear interpolator. As a result, dependences of the bit error rate on the Eb/N0 in various channels were obtained. An error rate of 10−4 was achieved under the Eb/N0 equal to 13.4 dB, 15.3 dB and 20.9 dB in the first, second and third channel, respectively.Conclusion. A FBMC/OQAM-based transmission system with a linear equalizer can operate without a cyclic prefix in a multipath wireless channel, providing comparable noise immunity to OFDM-CP. Long frames should be used to obtain greater spectral efficiency, due to the presence of a transition zone at the beginning and end of the FBMC/OQAM frame.

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29

Lee, Joohyoung, Jeongha An, Hyung-in Ra, and Kiman Kim. "Long-Range Acoustic Communication Using Differential Chirp Spread Spectrum." Applied Sciences 10, no. 24 (December 10, 2020): 8835. http://dx.doi.org/10.3390/app10248835.

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Here, we propose a new modulation method using chirp spread spectrum (CSS) modulation to indicate the result of long-range acoustic communication (LRAC). CSS modulation had outstanding matched filter characteristics even though the channel was complex. The performance of the matched filter depends on the time–bandwidth product. We studied the method of using the same modulation method while increasing the amount of the time–bandwidth product. When differential encoding is applied, the de-modulation is made using the difference between the current symbol and the previous symbol. If the matched filter is applied using both the current and the previous symbol, such as the use of two symbols, the amount of the time–bandwidth product can be doubled, and this method can make the output of the matched filter larger. The proposed method was verified in lake and sea experiments, in which the experimental environment was analyzed and compared with the result using the channel impulse response (CIR) of the lake and sea. The lake experiment was conducted over a distance of about 100–300 m between the transmitter and receiver and at a depth of ~40 m. As a result of the communication, the conventional method’s bit error rate (BER) was 1.22×10−1, but the proposed method’s BER was 1.98×10−2. The sea experiment was conducted over a distance of ~90 km and at a depth of ~1 km, and the conventional method BER in this experiment was 1.83×10−4, while the proposed method’s BER was 0.

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30

Dyachenko A. A., Blashenkov N. M., Berdnikov A. S., Gall L. N., Samsonova N. S., Semenov A. A., and Gall N. R. "Specialized mass spectrometer for determining the isotopic composition of lithium by ERIAD (electrospray with in source atomization)." Technical Physics Letters 48, no. 7 (2022): 1. http://dx.doi.org/10.21883/tpl.2022.07.54025.18919.

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A specialized isotope mass spectrometer for determining the isotopic ratio of lithium by ERIAD (electrospray with atomization in an ion source) is described. The device uses a Mattuha-Herzog-type mass analyzer with double focusing to use ion beams with a large spread in energy and simultaneous registration of signals of both lithium isotopes (6Li and 7Li), and a two-channel receiver based on a doublet of microchannel plates. The gas-dynamic interface is built according to the Kontorowitz-Gray scheme; from the gas-dynamic point of view, it is "long", that is, the distance between the nozzle and the skimmer is 4 times the size of the "Mach barrel" at the operating pressure (200 Pa). The device is desktop, its weight does not exceed 20 kg. The measurement time is 1000 s, sample replacement time is 100 s, measurement accuracy is ~ 0.1%. Keywords: mass spectrometry, electrospray, ion source, isotopes of lithium.

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31

Soré, Souleymane, Yacouba Sawadogo, Juste Isidore Bonkoungou, Sephora P. Kaboré, Saidou Béogo, Charles Sawadogo, Boubié G. Bationo, et al. "Detection, identification and characterization of extended-spectrum beta-lactamases producing Enterobacteriaceae in wastewater and salads marketed in Ouagadougou, Burkina Faso." International Journal of Biological and Chemical Sciences 14, no. 8 (December 8, 2020): 2746–57. http://dx.doi.org/10.4314/ijbcs.v14i8.8.

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Extended spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) represent a threat for failure of empirical antibiotic therapy and are associated with high mortality, morbidity and expenses. The aims of this study was to determine the prevalence of ESBL-PE and multidrug resistant enterobacteria (MDR), enterobacteria profil, investigate the associated resistance in wastewater and salads. After wastewater and salad sampling, enterobacteria was isoled on (EMB + 4μg / L cefotaxim). The stains of Enterobacteriaceae were identified by using biochemical methods and confirmed as ESBL by double-disc synergy test (amoxicillin/clavulanic acid with cefotaxime 30 μg, ceftazidime 30 μg and ceftriaxone 30 μg). Finally, the associated resistance was investigated by testing the susceptibility of the strains by the disc diffusion method. Global prevalence of ESBL-PE was 53.92% (95% CI: 48,2-59,5) (153/293), 61.11% from wastewater and 42.47% from salads. Major ESBL-E was Escherichia coli (73.44%), followed by Klebsiella pneumoniae (21.88%). Resistance to the aminoglycoside , fluroquinolonones and sulfonamides classes were dominant, observed in 53,83%, 93,86% and 98,95% of the isolates, respectively. The frequence of MDR was hight to channel1 (32,40%) and channel2 (26,26%). This study reports very worrying results. There is an urgent need to develop measures to monitor the spread of these multidrug-resistant strains.Keywords: Wastewater, ESBL-PE, Salads, Ouagadougou.

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32

Zhang, Lan, Xiao Mei Xu, Wei Feng, and You Gan Chen. "Doppler Estimation, Synchronization with HFM Signals for Underwater Acoustic Communications." Applied Mechanics and Materials 198-199 (September 2012): 1638–45. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.1638.

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This paper presents the application of the hyperbolic frequency modulated (HFM) signal to acoustic propagation in order to improve the performance of underwater acoustic (UWA) communications. Due to the large delay spread caused by multipath propagation and the severe Doppler Effect of the channel, we propose the using of double HFM signals as preambles for Doppler estimation, frame synchronization in UWA communications. A theoretical analysis about Doppler-invariability of HFM signals was provided firstly, then some numerical simulations about Doppler estimation were implemented, and experiments on testing performance of double-HFM preambles for frame synchronization in the pool were carried out as well. The simulation and experimental results show that using double-HFM signals as preambles has the capability to take an explicit Doppler estimation and retiming for frame synchronization, demonstrating that it has a good prospect in underwater acoustic communication system, especially for moving platforms.

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33

Ovcharov, A. "Financial Crises and Financial Contagion in Latin America." World Economy and International Relations 67, no. 2 (2023): 104–13. http://dx.doi.org/10.20542/0131-2227-2023-67-2-104-113.

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The article deals with modern financial crises and features of their spread in Latin America. The classification of crises and ways of their identification are presented. The interconnectedness of modern financial crises is emphasized, which leads to the emergence of double and triple crises. Such crises have been repeatedly recorded in Argentina, Mexico, Uruguay and other countries. Over a period of more than fifty years, Latin America experienced 165 financial crises, with the largest share of them occurring in currency crises. The article proposes the indicator “crisis burden on the countries of Latin America” – its calculation for the period 1970–2019 showed that the region is characterized by alternating growth and decrease in the burden from banking and currency crises with a relatively stable load from debt crises. The maximum intensity of financial crises was observed in the 1970–1980, and then it decreased, although there were isolated spikes. The interconnectedness of crises is analyzed in the context of the effects of financial contagion – the transmission of shocks through different channels from one country or region to another country or region. Two main approaches explaining the mechanisms of transmission of crises between countries have been allocated. The results of studies indicating the direction and extent of financial contagion in Latin America were discussed. In particular, it is shown that contagion in the crisis periods of 1990–2000 spread both within the region and from the United States through trade and financial channels. The article presents the results of its own empirical study, which also confirmed the existence of contagion in this region. For the calculations, daily data on the stock indices of 8 Latin American countries over a long period of time were used. With the help of econometric tests for shifts in correlations (Forbes-Rigobon test and coskewness test), it was found that the recipients of contagion that spread through the stock market channels from the United States during the global financial crisis of 2007–2009 were countries such as Argentina, Brazil, Colombia and Mexico. During the crisis caused by the spread of COVID‑19, only Mexico was susceptible to contagion. This made it possible to draw a conclusion about the resilience of Latin American economies to the pandemic shock and the effectiveness of restrictive government measures.

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34

Qian, Sen, Qi Wu, Lishuang Ma, Yao Zhu, Min Yan, Lingfeng Zhang, Shuo Peng, and Zhigang Wang. "Simulation of FPMT with single chip MCP." Journal of Physics: Conference Series 2374, no. 1 (November 1, 2022): 012135. http://dx.doi.org/10.1088/1742-6596/2374/1/012135.

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Micro-channel plate photomultiplier tube (MCP-PMT) is a kind of photosensitive device with single photon detection capability and great time resolution, which is also called Fast-PMT (FPMT). The MCP is the electron multiplier structure and in order to achieve single photon detection, two layers of MCPs are always used together. Due to the new-generation particle accelerators with high energy and luminosity, the time resolution of the detector is more important than single-photon detection capability. The single-chip-FPMT is expected to have a greater time resolution. Based on the CST STUDIO SUITE, the single-chip-FPMT model is built and the time performances including the rise time and transit time spread are compared with the double-chips-FPMT model under the same parameter setting. The results show that the FPMT model with single chip MCP has better time response and resolution than the traditional double-chips-FPMT.

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35

Onderwaater, Jaap, Jan Wams, and Hans Potters. "Geophysics in Oman." GeoArabia 1, no. 2 (April 1, 1996): 299–324. http://dx.doi.org/10.2113/geoarabia0102299.

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ABSTRACT To date Petroleum Development Oman has acquired approximately 200,000 kilometers of 2-D and 20,000 square kilometers of 3-D seismic data. Five 3-D and one 2-D crews are operated by contractors. For 3-D surveys PDO uses 2 vibrator source groups recording a “double zig-zag”. The vibrators have GPS systems. The standard spread consists of 4 receiver lines of 120 active channels, spaced 200 meters apart, with receiver spacing of 50 meters. Bin size is 25 by 25 meters, multiplicity is 60 fold and the active spread is 6 kilometers. Most of the seismic data is processed inhouse by CGG. Additionally PDO uses proprietary software for bench-marking, training and attribute studies. Recent lines recorded with vibroseis, rather than thumper, and long offsets (4 to 6 km compared to 2 km) have improved both shallow (1 to 1.5 second) and deep reflections including sub-salt events (>2.5 second). Improved data quality has better imaged exploration targets (e.g. post-salt Haima and intra-salt Athel) and reservoir geometry (e.g. Alkhlata and Gharif). Proper imaging of the Athel silicilyte may require 3-D pre-stack depth migration. The application of other geophysical techniques including gravity, aeromagnetics, seismic attribute analysis and borehole geophysics has also proven useful, particularly where conventional seismic data quality is poor.

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36

Michaely, Erez. "Type Ia supernovae from wide white dwarfs triples." Monthly Notices of the Royal Astronomical Society 500, no. 4 (November 21, 2020): 5543–51. http://dx.doi.org/10.1093/mnras/staa3623.

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ABSTRACT For ultra-wide systems (with outer orbit >103 au) the galactic field is collisional. Hence, ultra-wide triple white dwarfs (TWDs) can be perturbed, by flyby stars, to sufficiently high outer eccentricity such that the triple becomes dynamically unstable. An unstable triple undergoes multiple binary–single resonant encounters between all three WDs. These encounters might result in a direct collision between any random two WDs and lead to a Type Ia supernova (SN Ia) event. In case where the multiple resonant encounters did not produce a collision a compact binary is formed (while the third WD is ejected), this binary either collides or merges via gravitational wave emission, similar to the classic double-degenerate (DD) channel. In this research study we estimate the galactic rates of SN Ia from the direct collision channel is to be $0.11\!-\!3.76{{\ \rm per\ cent}}$ and primarily $1\!-\!36{{\ \rm per\ cent}}$ from the DD scenario. The spread in the range is due to uncertainty in the underlying population and two types of galaxies, where elliptical galaxies host higher fraction. and primarily $2\!-\!36{{\ \rm per\ cent}}$ from the DD scenario.

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37

Wu, Tao, Xiaofeng Zhang, Yiwen Li, Zhenghong Deng, and Yijie Huang. "On Spatial Smoothing for DOA Estimation of 2D Coherently Distributed Sources with Double Parallel Linear Arrays." Electronics 8, no. 3 (March 23, 2019): 354. http://dx.doi.org/10.3390/electronics8030354.

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Considering coherently-distributed (CD) sources are correlated with each other, a two-dimensional (2D) coherent CD source model is proposed according to the characteristics of an underwater acoustic channel. Under the assumption of small angular spreads, rotational invariance relationships within and between subarrays of double parallel linear arrays are derived. As the covariance matrix of spatial smoothing obtained from receive vectors expressed by rotational invariance relationships is proven to be full rank, decoherence of the 2D coherent CD source is proposed by spatial smoothing of the double parallel linear arrays. A propagator method base on spatial smoothing (SS-PM) and estimation of signal parameters via rotational invariance techniques (ESPRIT) base on spatial smoothing (SS-ESPRIT) method established by covariance matrix of spatial smoothing are proposed. The proposed methods do not require peak-searching, angles matching and information of deterministic angular signal distribution function. Simulations are conducted to verify the effectiveness of the proposed methods.

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38

Deaconu, Adela, and Crina I. Filip. "The economy and accounting sophistication: An overview of Transylvania." Accounting History 22, no. 1 (November 30, 2016): 92–123. http://dx.doi.org/10.1177/1032373216668183.

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Based on historiography and documentary research, this study juxtaposes the economic history of the Principality of Transylvania against the general evolution of accounting practice and thought, and makes comparisons with the general European context. Along with providing evidence for a less-researched area, the discussion on the sophistication of accounting through successive stages – from 1541 to 1918 – is useful for enabling other regional comparative studies. This study argues that there was a delay in the evolution of accounting in Transylvania compared to the development of European accounting, with the gap growing smaller towards the end of World War I. The pace of economic development, initially extremely slow, increased and triggered the emergence of capitalism, hence the development of double-entry bookkeeping and scientific accounting. In this way, Sombart’s ideas and the post-Sombart theses are supported. Imperial (Austro-Hungarian) political domination and the region’s social structure played an important role in this setting. Observing other external channels of the spread of accounting, the study confirms the validity of the diffusionist theory.

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39

Chow, Cheuk Lun. "NUMERICAL STUDIES ON SMOKE SPREAD IN THE CAVITY OF A DOUBLE-SKIN FAÇADE / SKAITINIS DŪMŲ SKLIDIMO DVIGUBO FASADO ERTMĖJE TYRIMAS." Journal of Civil Engineering and Management 17, no. 3 (September 20, 2011): 371–92. http://dx.doi.org/10.3846/13923730.2011.595075.

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Double-skin façade (DSF) is an environmental friendly architectural feature. However, fire hazard is a concern. A scenario of having a flashover room fire adjacent to the façade was identified. Heat and mass would be trapped in the façade cavity. This paper examines air flow driven out of a flashover room fire to the cavity of a DSF by Computational Fluid Dynamics. The software Fire Dynamics Simulator developed at the Building and Fire Research laboratory, National Institute of Standards and Technology, USA was selected as the simulation tool. Three DSF features labeled as DSF1, DSF2 and DSF3 were considered. Detailed simulations were carried out to understand the fire-induced aerodynamics in a 5-level model DSF1 with a fire room at the third level. Hot gas spreading out to the façade cavity was simulated under two heat release rates of 1 MW and 5 MW. Air cavity depths of 0.5 m, 1 m, 1.5 m and 2 m were considered. Three stages of flame spreading out to a DSF with a wide air cavity depth were identified. Results suggested that wider air cavity depths would be more dangerous, with higher risk of the upper interior glass pane's breaking. To study spreading of heat and mass up the façade cavity as vertical channel flow, two taller DSF façade features DSF2 and DSF3 with differing air cavity depths were simulated. Both features were of height 24 m but of differing fire room height. Vertical temperature profiles with and without the DSF feature were compared. Santrauka Dvigubas fasadas yra ekologiškas architektūrinis sprendimas. Tačiau dvigubas fasadas yra problemiškas gaisrinės saugos požiūriu. Nagrinėjamas scenarijus, kai greta dvigubo fasado esančioje patalpoje įvyksta gaisro pliūpsnis. Dvigubo fasado ertmėje gali būti uždaryti karštis ir masė. Taikomi skaitmeninės skysčių dinamikos metodai nustatyti, kaip iš patalpos, kurįoje įvyksta gaisro pliūpsnis, oras ir degimo produktai išstumiami ī dvigubo fasado ertmę. Modeliuoti naudojama kompiuterinė programa, parengta JAV Nacionaliniame standartų ir technologijos institute. Nagrinėjami trys dvigubų fasadų sprendimai. Atliekamas detalus pirmojo sprendimo fasado modeliavimas siekiant suprasti gaisro lemiamą aerodinamiką penkių aukštų fasade, kai gaisras kyla trečiame aukšte. Modeliuojamas karštu dujų sklidimas iš fasado ertmės viršaus teigiant, kad gaisro išskiriama Siluma yra 1 MW ir 5 MW. Ertmės plotis imamas lygiu 0,5 m, 1,5 m ir 2 m. Nustatomi trys liepsnos sklidimo iš dvigubo fasado etapai. Gauti rezultatai leidžia daryti išvadą, kad platesni fasadai yra pavojingesni, nes didina viršutinių stiklo diskų dužimo tikimybę. Aukštesni antro ir trečio sprendimo fasadai naudoti tirti, kaip karštis ir masė juda vertikalia fasado ertme. Skyrėsi šių fasadų ertmės plotis. Abu fasadai buvo 24 m aukščio, tačiau skyrėsi gaisro patalpos aukštis. Buvo palygintas vertikalusis temperatūros pasiskirstymas dvigubo fasado ertmėje.

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40

Godfrey, A., N. C. Krieger Lassen, D. A. Hughes, and D. Juul Jensen. "Investigation of Medium to High Strain Deformation Microstructures Using an Automated Electron Backscattering Pattern (EBSP) System." Microscopy and Microanalysis 4, S2 (July 1998): 280–81. http://dx.doi.org/10.1017/s1431927600021528.

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The speed of automated EBSP orientation gathering has now increased to a point where it is possible to examine large areas of deformed material at a resolution close to the length scale of the dislocation substructures involved (typically <1μm for strains of greater than ∊= l). Investigation of such deformed samples invariably gives rise to diffraction images of low quality and to many double patterns. To assist in a critical selection of the data, it is usual to store a measure of the indexing confidence for each point. Here we describe how deformed samples, which provide the appropriate range of pattern qualities, can be used to calibrate acceptance criteria for unsupervised EBSP measurements on deformation microstructures. An application in the use of such criteria is also described.Two crystals, chosen with orientations that are known to develop a well defined texture spread during deformation, were channel die deformed to a strain of ∊=1.5 (78% reduction).

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41

Schiller, Yitzhak. "Inter-Ictal- and Ictal-Like Epileptic Discharges in the Dendritic Tree of Neocortical Pyramidal Neurons." Journal of Neurophysiology 88, no. 6 (December 1, 2002): 2954–62. http://dx.doi.org/10.1152/jn.00525.2001.

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Dendritic mechanisms have been implied to play a key role in the formation of epileptic discharges. However, presently only a handful of direct dendritic recordings have been reported during epileptic discharges. In this study, I performed simultaneous voltage recordings from the soma and apical dendrite of the same neuron combined with calcium-imaging measurements to investigate inter-ictal- and ictal-like epileptic discharges in dendrites of layer 5 pyramidal neurons. Neocortical brain slices treated with bicuculline (BCC) produced both isolated “inter-ictal” paroxysymal depolarization shift (PDS) responses and electrographic seizures. Concomitant voltage recordings from the soma and apical dendrite revealed that PDS responses developed in both the apical dendrites and soma. However, the two responses differed from one another. In apical dendrites, the PDS was significantly higher in amplitude and shorter in duration compared with the somatic PDS. The PDS response in dendrites had a peak amplitude of 68.9 ± 2.2 (SD) mV, peak voltage value of 9.3 ± 2.7 mV, and half-width of 203.8 ± 38.4 ms. In contrast, the somatic PDS had a peak amplitude of 48.7 ± 2.7 mV, peak voltage value of −11.9 ± 3.1 mV, and half-width of 247.8 ± 57.3 ms ( P < 0.01, n = 18). In addition the apical dendritic PDS always preceded the somatic counterpart in all 18 neurons examined. Concomitant calcium-imaging measurements showed the PDS evoked large calcium influx into the entire dendritic tree including the apical tuft, basal, and oblique dendrites. The PDS evoked [Ca2+]i were not uniform along the dendritic tree, being highest in the oblique dendrites (71.3 ± 14.5 μM) and lowest at the distal tuft branches (9.3 ± 0.7 μM). The PDS responses persisted after blockade of voltage-gated sodium channels by intracellular QX-314 but became narrower (by 69.6 ± 9.7%) following intracellular administration of the voltage-gated calcium channel blocker D600. Electrographic seizures recorded in the soma and apical dendrites were composed of recurrent bursts. The initial bursts represented PDS responses. During the seizure the amplitude of bursts gradually attenuated and reached an average value of 26 ± 13% of the initial ictal PDS burst. Double recordings during electrographic seizures revealed the initial one to four ictal bursts appeared first at the apical dendrite while later ictal bursts were always observed first at the soma. In conclusion, the results of this study show “inter-ictal” PDS responses originated in the apical dendritic tree, were partially mediated by voltage-gated calcium channels and spread throughout the dendritic tree including the fine tuft, basal, and oblique dendrites. During electrographic seizures the origin of epileptic bursts shifted from the apical dendritic tree to the soma-basal region.

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42

So, Min-Kyung, Sholhui Park, Kyunghoon Lee, Soo-Kyung Kim, Hae-Sun Chung, and Miae Lee. "Variant Prediction by Analyzing RdRp/S Gene Double or Low Amplification Pattern in Allplex SARS-CoV-2 Assay." Diagnostics 11, no. 10 (October 8, 2021): 1854. http://dx.doi.org/10.3390/diagnostics11101854.

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The spread of delta variants (B.1.671.2) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a severe global threat. Multiplex real-time PCR is a common method for confirming SARS-CoV-2 infection, however, additional tests, such as whole genomic sequencing, are required to reveal the presence or type of viral mutation. Moreover, applying whole genomic sequencing to all SARS-CoV-2 positive samples is challenging due to time and cost constraints. Here, we report that the double or low amplification curve observed during RNA-dependent RNA polymerase (RdRp) gene/S gene amplification in the Allplex SARS-CoV-2 Assay is related to delta/alpha variants. We analyzed the RdRp/S gene amplification curve using 94 samples confirmed as SARS-CoV-2 infection by the Allplex SARS-CoV-2 Assay from January to August, 2021. These positive samples identified variant types using the Novaplex SARS-CoV-2 Variants I and IV Assays. Overall, 17 samples showing a double curve and 11 samples showing a low amplification pattern were associated with alpha-/delta-type strains with variants in the P681 region. The double or low curve shown in the RdRp gene amplification curve had 100% sensitivity and 100% specificity for diagnosing delta/alpha variants. During the SARS-CoV-2 virus diagnostic RT-PCR test using the Allplex SARS-CoV-2 Assay, we could consider the presence of delta/alpha variants in the samples with double or low amplification curve of the RdRp/S gene channel. This PCR amplification curve abnormality enables rapid and cost-effective variant type prediction during SARS-CoV-2 diagnostic testing in clinical laboratories.

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43

Zhao, Wenhua, Xingliang Xu, Niandu Wu, Xiaodie Zhao, and Jiangfeng Gong. "Dandelion-Like CuCo2O4@ NiMn LDH Core/Shell Nanoflowers for Excellent Battery-Type Supercapacitor." Nanomaterials 13, no. 4 (February 14, 2023): 730. http://dx.doi.org/10.3390/nano13040730.

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Dandelion-like CuCo2O4 nanoflowers (CCO NFs) with ultrathin NiMn layered double hydroxide (LDH) shells were fabricated via a two-step hydrothermal method. The prepared CuCo2O4@NiMn LDH core/shell nanoflowers (CCO@NM LDH NFs) possessed a high specific surface area (~181 m2·g−1) with an average pore size of ~256 nm. Herein, the CCO@NM LDH NFs exhibited the typical battery-type electrode material with a specific capacity of 2156.53 F·g−1 at a current density of 1 A·g−1. With the increase in current density, the rate capability retention was 68.3% at a current density of 10 A·g−1. In particular, the 94.6% capacity of CCO@NM LDH NFs remains after 2500 cycles at 5 A·g−1. An asymmetric supercapacitor (ASC) with CCO@NM LDH NFs//activated carbon (AC) demonstrates a remarkable capacitance of 303.11 F·g−1 at 1 A·g−1 with excellent cycling stability. The coupling and synergistic effects of multi-valence transition metals provide a convenient channel for the electrochemical process, which is beneficial to spread widely within the realm of electrochemical energy storage.

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44

Duan, Yueyan. "How Can Social Media Play a Role in Combating Fake News." Lecture Notes in Education Psychology and Public Media 4, no. 1 (May 17, 2023): 823–28. http://dx.doi.org/10.54254/2753-7048/4/2022438.

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The shift from a mass media culture to a social media culture has allowed people to access information in more diverse ways. The emergence of social media has provided people with a fast and efficient platform to exchange information and has gradually become the main channel for people to share information and get news. However, the double-edged sword effect of social media has gradually become apparent, with a large number of fake news stories mixed in. This paper will examine six different types of fake news through a literature review approach: satire, parody, fabrication, manipulation, advertising and propaganda, and the motives of the purveyors. It also uses the COVID-19 pandemic as a background and selects social media such as Facebook and Twitter to discuss the role they play in combating fake news, misinformation, and disinformation. Facebook has taken the approach of partnering with professional agencies to provide accurate information about the epidemic on its social media platforms; Twitter has also reduced the amount of misinformation spread by adjusting its internal algorithmic pushing mechanism and hashtags.

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45

Yue, Wei, Na Liu, Qiujie Zheng, and H. Holly Wang. "Does the COVID-19 Pandemic Change Consumers’ Food Consumption and Willingness-To-Pay? The Case of China." Foods 10, no. 9 (September 12, 2021): 2156. http://dx.doi.org/10.3390/foods10092156.

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Анотація:

Since COVID-19 was first detected in China in 2019, governments around the world have imposed strict measures to curb the spread of the coronavirus, which substantially impacted people’s life. Consumers’ food consumption behavior has also changed accordingly with reduced grocery shopping frequency, replaced in-person grocery shopping with online shopping, and increased valuation on food. In this paper, we aim to investigate the change in Chinese consumers’ food consumption and their willingness to pay (WTP) for vegetables and meat, using a dataset with 1206 online samples collected between February and March 2020. Consumers’ WTP for vegetables and meat is estimated using a double-bounded dichotomous contingent valuation design, and factors affecting their WTPs are also investigated. Results show that consumers have a higher WTP for these food products during the pandemic, and their WTP is positively affected by their anticipated duration of the COVID-19, their online shopping shares, their direct exposure to infected patients, their gender, and their income. These results imply that the food industry shall try to develop online market channels as consumers are willing to share the costs, while lower-income consumers may not be able to meet their food needs with prices increased beyond their WTP and thus may call for the government’s support.

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46

Ayadi, Raouia, Inès Kammoun, and Mohamed Siala. "Efficient Offline Waveform Design Using Quincunx/Hexagonal Time-Frequency Lattices." Wireless Communications and Mobile Computing 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/9207108.

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Анотація:

Conventional orthogonal frequency division multiplexing (OFDM) may turn to be inappropriate for future wireless cellular systems services, because of extreme natural and artificial impairments they are expected to generate. Natural impairments result from higher Doppler and delay spreads, while artificial impairments result from multisource transmissions and synchronization relaxation for closed-loop signaling overhead reduction. These severe impairments induce a dramatic loss in orthogonality between subcarriers and OFDM symbols and lead to a strong increase in intercarrier interference (ICI) and intersymbol interference (ISI). To fight against these impairments, we propose here an optimization of the transmit/receive waveforms for filter-bank multicarrier (FBMC) systems, with hexagonal time-frequency (TF) lattices, operating over severe doubly dispersive channels. For this, we exploit the Ping-pong Optimized Pulse Shaping (POPS) paradigm, recently applied to rectangular TF lattices, to design waveforms maximizing the signal-to-interference-plus-noise ratio (SINR) for hexagonal TF lattices. We show that FBMC, with hexagonal lattices, offers a strong improvement in SINR with respect to conventional OFDM and an improvement of around 1 dB with respect to POPS-FBMC, with rectangular lattices. Furthermore, we show that hexagonal POPS-FBMC brings more robustness to frequency synchronization errors and offers a 10 dB reduction in out-of-band (OOB) emissions, with respect to rectangular POPS-FBMC.

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47

Jong, D. S., P. C. Pape, S. M. Baylor, and W. K. Chandler. "Calcium inactivation of calcium release in frog cut muscle fibers that contain millimolar EGTA or Fura-2." Journal of General Physiology 106, no. 2 (August 1, 1995): 337–88. http://dx.doi.org/10.1085/jgp.106.2.337.

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Анотація:

Cut muscle fibers from Rana temporaria (sarcomere length, 3.4-4.2 microns) were mounted in a double Vaseline-gap chamber (14-15 degrees C) and equilibrated with end-pool solutions that contained 20 mM EGTA and 1.76 mM Ca. Sarcoplasmic reticulum (SR) Ca release was estimated from changes in pH (Pape, P. C., D.-S. Jong, and W.K. Chandler. 1995. Journal of General Physiology. 106:000-000). Although the amplitude and duration of the [Ca] transient, as well as its spatial spread from the release sites, are reduced by EGTA, SR Ca release elicited by either depolarizing voltage-clamp pulses or action potentials behaved in a manner consistent with Ca inactivation of Ca release. After a step depolarization to -20 or 10 mV, the rate of SR Ca release, corrected for SR Ca depletion, reached a peak value within 5-15 ms and then rapidly decreased to a quasi-steady level that was about half the peak value; the time constant of the last half of the decrease was usually 2-4 ms. Immediately after an action potential or a 10-15 ms prepulse to -20 mV, the peak rate of SR Ca release elicited by a second stimulation, as well as the fractional amount of release, were substantially decreased. The rising phase of the rate of release was also reduced, suggesting that at least 0.9 of the ability of the SR to release Ca had been inactivated by the first stimulation. There was little change in intramembranous charge movement, suggesting that the changes in SR Ca release were not caused by changes in its voltage activation. These effects of a first stimulation on the rate of SR Ca release elicited by a second stimulation recovered during repolarization to -90 mV; the time constant of recovery was approximately 25 ms in the action-potential experiments and approximately 50 ms in the voltage-clamp experiments. Fura-2, which is able to bind Ca more rapidly than EGTA and hence reduce the amplitude of the [Ca] transient and its spatial spread from release sites by a greater amount, did not prevent Ca inactivation of Ca release, even at concentrations as large as 6-8 mM. These effects of Ca inactivation of Ca release can be simulated by the three-state, two-step model proposed by Schneider, M. F., and B. J. Simon (1988, Journal of Physiology. 405:727-745), in which SR Ca channels function as a single uniform population of channels. (ABSTRACT TRUNCATED AT 400 WORDS)

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48

Iroume, Junior Yves-Audrey, Raphaël Onguéné, Francis Djanna Koffi, Antoine Colmet-Daage, Thomas Stieglitz, Willy Essoh Sone, Sakaros Bogning, et al. "The 21st August 2020 Flood in Douala (Cameroon): A Major Urban Flood Investigated with 2D HEC-RAS Modeling." Water 14, no. 11 (May 31, 2022): 1768. http://dx.doi.org/10.3390/w14111768.

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A major flood event occurred on 21 August 2020 in the densely populated Makèpè Missokè neighborhood in the city of Douala (Cameroon, Africa). Nearly 2210 buildings and 12,376 victims spread over 82 hectares were affected. A 2D HEC-RAS model is applied to simulate and characterize this event. A cross analysis of flood depth and flow velocity is used to classify the flood risk and identify areas exposed from low to high hazard. The simulations provide detailed information on the flood characteristics (extent, depth, velocity, arrival time, and duration). The simulated maximum water surface profiles are consistent with the floods marks with differences ranging from 0.02 m to 0.44 m, indicating a good agreement between the observed and simulated water levels at the peak flow (NSE = 0.94, Erel = 0.92, RMSE = 0.21 m). The maximum inundation level is 4.48 m and the flow velocity is globally low at less than 1 m/s. The average flood arrival time and duration are 5 h and 26 h, respectively, for a threshold height of 0.5 m. These results indicate a fast mobilization of the major river channel for the evacuation of this flood. The level of accuracy of the developed model of the 21 August 2020 flood event is appropriate for flood hazard assessment in the city of Douala and is designed to find operational application in future events.

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49

Takase, Shintaro, Kouta Miyagawa, and Hisafumi Ikeda. "Label-Free Detection of Zeptomol miRNA via Peptide Nucleic Acid Hybridization Using Novel Cyclic Voltammetry Method." Sensors 20, no. 3 (February 4, 2020): 836. http://dx.doi.org/10.3390/s20030836.

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Анотація:

To harness the applicability of microribonucleic acid (miRNA) as a cancer biomarker, the detection sensitivity of serum miRNA needs to be improved. This study evaluated the detection sensitivity of miRNA hybridization using cyclic voltammograms (CVs) and microelectrode array chips modified with peptide nucleic acid (PNA) probes and 6-hydroxy-1-hexanethiol. We investigated the PNA probe modification pattern on array chips using fluorescently labeled cDNA. The pattern was not uniformly spread over the working electrode (WE) and had a one-dimensional swirl-like pattern. Accordingly, we established a new ion-channel sensor model wherein the WE is negatively biased through the conductive π–π stacks of the PNA/DNA duplexes. This paper discusses the mechanism underlying the voltage shift in the CV curves based on the electric double-layer capacitance. Additionally, the novel hybridization evaluation parameter ΔE is introduced. Compared to conventional evaluation using oxidation current changes, ΔE was more sensitive. Using ΔE and a new hybridization system for ultrasmall amounts of aqueous solutions (as low as 35 pL), 140 zeptomol label-free miRNA were detected without polymerase chain reaction (PCR) amplification at an adequate sensitivity. Herein, the differences in the target molar amount and molar concentration are elucidated from the viewpoint of hybridization sensitivity.

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50

Kang, Hyun, and Hyoung-Chul Oh. "Current concerns on journal article with preprint: Anesthesia and Pain Medicine perspectives." Anesthesia and Pain Medicine 18, no. 2 (April 30, 2023): 97–103. http://dx.doi.org/10.17085/apm.23036.

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Анотація:

Preprints are preliminary research reports that have not yet been peer-reviewed. They have been widely adopted to promote the timely dissemination of research across many scientific fields. In August 1991, Paul Ginsparg launched an electronic bulletin board intended to serve a few hundred colleagues working in a subfield of theoretical high-energy physics, thus launching arXiv, the first and largest preprint platform. Additional preprint servers have since been implemented in different academic fields, such as BioRxiv (2013, Biology; www.biorxiv.org) and medRxiv (2019, Health Science; www.medrxiv.org). While preprint availability has made valuable research resources accessible to the general public, thus bridging the gap between academic and non-academic audiences, it has also facilitated the spread of unsupported conclusions through various media channels. Issues surrounding the preprint policies of a journal must be addressed, ultimately, by editors and include the acceptance of preprint manuscripts, allowing the citation of preprints, maintaining a double-blind peer review process, changes to the preprint’s content and authors’ list, scoop priorities, commenting on preprints, and preventing the influence of social media. Editors must be able to deal with these issues adequately, to maintain the scientific integrity of their journal. In this review, the history, current status, and strengths and weaknesses of preprints as well as ongoing concerns regarding journal articles with preprints are discussed. An optimal approach to preprints is suggested for editorial board members, authors, and researchers.

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