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Soriano, Jonathan y Sarah Marzen. "How Well Can We Infer Selection Benefits and Mutation Rates from Allele Frequencies?" Entropy 25, n.º 4 (4 de abril de 2023): 615. http://dx.doi.org/10.3390/e25040615.
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Experimentalists observe allele frequency distributions and try to infer mutation rates and selection coefficients. How easy is this? We calculate limits to their ability in the context of the Wright-Fisher model by first finding the maximal amount of information that can be acquired using allele frequencies about the mutation rate and selection coefficient– at least 2 bits per allele– and then by finding how the organisms would have shaped their mutation rates and selection coefficients so as to maximize the information transfer.
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Ma, Debiao, Junteng Zheng y Lizhi Peng. "Performance Evaluation of Epileptic Seizure Prediction Using Time, Frequency, and Time–Frequency Domain Measures". Processes 9, n.º 4 (13 de abril de 2021): 682. http://dx.doi.org/10.3390/pr9040682.
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The prediction of epileptic seizures is crucial to aid patients in gaining early warning and taking effective intervention. Several features have been explored to predict the onset via electroencephalography signals, which are typically non-stationary, dynamic, and varying from person-to-person. In the former literature, features applied in the classification have shared similar contributions to all patients. Therefore, in this paper, we analyze the impact of the specific combination of feature and channel from time, frequency, and time–frequency domains on prediction performance of disparate patients. Based on the minimal-redundancy-maximal-relevance criterion, the proposed framework uses a sequential forward selection approach to individually find the optimal features and channels. Trained models could discriminate the pre-ictal and inter-ictal electroencephalography with a sensitivity of 90.2% and a false prediction rate of 0.096/h. We also present the comparison between the classification accuracy obtained by the optimal features, several features summarized from optimal features, and the complete set of features from three domains. The results indicate that various patient interpretations have a certain specificity in the selection of feature-channel. Furthermore, the detailed list of optimal features and summarized features are proffered for reference to those who research the corresponding database.
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Luhanga, Matthew L. "Packet Error Probability for Diversity Systems in Slow Rayleigh Fading and Gaussian Noise". International Journal of Electrical Engineering & Education 23, n.º 3 (julio de 1986): 239–44. http://dx.doi.org/10.1177/002072098602300309.
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Analytical results on packet error probability for noncoherent frequency-shift-keying (NCFSK) and differential phase-shift-keying (DPSK) systems with diversity reception operating over slow Rayleigh fading channels with Gaussian noise are derived. Expressions obtained are applicable to two linear combining schemes: selection combining and maximal-ratio combining.
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Kuroha, Akihiro, Chang-Jun Ahn, Tatsuya Omori y Ken-ya Hashimoto. "Multiuser Diversity OFDMA using Power Priority Selection and Adaptive Clipping". International Journal of Distributed Systems and Technologies 5, n.º 4 (octubre de 2014): 18–30. http://dx.doi.org/10.4018/ijdst.2014100102.
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In recent, orthogonal frequency division multiple access (OFDMA) has been used for a multiuser wireless communication. In a wireless network, the transmitted signal of each user has independent channel fluctuation characteristic. By using this characteristic, OFDMA can achieve the multiuser diversity (MUDiv). Until this time, to achieve a low complexity and performance improvement, the adaptive subcarrier block (ASB) and frequency symbol spreading (FSS) methods have been proposed. However, the system performance in a low Eb/N0 is worse than that of maximal sum capacity (MSC) and peak to average power ratio (PAPR) does not decrease greatly. To solve these problems, in this paper, we propose the subcarrier allocation with the power priority selection (PSS) and the adaptive clipping (AC) with the peak reduction signal to improve the system and PAPR performance.
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Trinh, Le-Huy y Fabien Ferrero. "Multiband Frequency Tuneable Antennas for Selection Combining Strategy in White Space Applications". Applied Sciences 12, n.º 21 (1 de noviembre de 2022): 11062. http://dx.doi.org/10.3390/app122111062.
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This article presents a reconfigurable antenna using digitally tuneable capacitors (DTCs). Mounted on a 120 × 200 mm2 ground plane, the radiating element has very compact dimensions of 0.06λg × 0.016λg × 0.0016λg (with λg being the wavelength at 585 MHz). The proposed structure could be operated in the white-space frequency band from 470 to 700 MHz. The antenna system is composed of two radiated elements that are placed at the corner of the board. The active components were soldered onto the antennas and controlled by an embedded microcontroller via the I2C interface. Antenna impedances were simulated and evaluated by measurement with an impedance-matching bandwidth of 39.32% (470–700 MHz) for an S11 less than −6 dB. Furthermore, the numerical results show a realized maximal gain ranging from −2.2 dBi at 470 MHz to 1.87 dBi at 700 MHz. Lastly, the diversity gains based on the radiation pattern of two resonators were calculated. The results show envelope correlation coefficient (ECC) values lower than 0.5 for the different configurations.
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Marden, J. H., M. R. Wolf y K. E. Weber. "Aerial performance of Drosophila melanogaster from populations selected for upwind flight ability." Journal of Experimental Biology 200, n.º 21 (1 de noviembre de 1997): 2747–55. http://dx.doi.org/10.1242/jeb.200.21.2747.
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A computerized system for three-dimensional tracking of large numbers of individual free-flying insects was used to assess the performance of Drosophila melanogaster from populations that had undergone 160 generations of selection for upwind flight ability. Compared with control lines, the selected lines showed significant increases in mean flight velocity, decreases in angular trajectory and a significant change in the interaction between velocity and angular trajectory. Maximal flight velocity was apparent as a sharply defined upper boundary of the distribution of horizontal and vertical velocity as a function of angular trajectory; this upper bound (0.85 ms-1) differed little between the selected and control lines, although individuals from the selected lines attained maximal performance levels much more frequently. Maximum induced power output was calculated directly from the product of maximum vertical velocity and body weight. This measure (28 W kg-1 muscle) was closely predicted by a scaling relationship derived from the load-lifting limits of larger insects and vertebrates, as well as tethered D. melanogaster stimulated via their optomotor reflex to produce maximal lift. These results indicate that selection for flight performance can readily alter the relative effort and/or the frequency of phenotypes capable of attaining population-wise maximal performance levels, but shows little ability to increase population-wise maximal performance.
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Bendelac, A., P. Matzinger, R. A. Seder, W. E. Paul y R. H. Schwartz. "Activation events during thymic selection." Journal of Experimental Medicine 175, n.º 3 (1 de marzo de 1992): 731–42. http://dx.doi.org/10.1084/jem.175.3.731.
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During their differentiation in the mouse thymus, CD4+8- cells undergo several of the sequential changes observed upon normal activation of mature, peripheral CD4+ lymphocytes. Expression of CD69, an early activation marker, is first observed on a minority of cells at the T cell receptor (TCR)lo/med double-positive stage, is maximal (50-90%) on heat-stable antigen (HSA)hi TCRhi double-positive, HSAhi TCRmed CD4+8lo, and HSAhi TCRhi CD4+8- cells, and is downmodulated at the mature HSAlo CD4+8- stage. In contrast, CD44, a late activation marker, is selectively expressed at the HSAlo stage. The set of lymphokines that CD4+8- thymocytes can produce upon stimulation also characteristically expands from mainly interleukin 2 (IL-2) at the HSAhi stage, to IL-2 and very large amounts of IL-4, IL-5, IL-10, and interferon gamma (IFN-gamma) at the HSAlo stage. 1 in 30 HSAlo CD4+8- adult thymocytes secrete IL-4 upon stimulation through their TCR. This frequency is 25% of the frequency of IL-2 producers, about 100-fold above that of peripheral (mainly resting) CD4+ T cells. With time after their generation in organ culture, CD4+8- thymocytes lose their capacity to secrete IL-4, IL-5, and IFN-gamma, but not IL-2. Similarly, the frequency of IL-4, but not of IL-2, producers progressively decreases after emigration to the periphery as judged by direct comparison between thymic and splenic CD4+ cells in newborns, or by following the fate of intrathymically labeled CD4+8- cells in adults after their migration to the spleen. This sequence suggests that thymic selection results from an activation process rather than a simple rescue from death at the double-positive stage, and shows that the functional changes induced after intrathymic activation, although transient, are still evident after export to the periphery.
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GRYLLIAS, KONSTANTINOS C. y IOANNIS ANTONIADIS. "A PEAK ENERGY CRITERION (P. E.) FOR THE SELECTION OF RESONANCE BANDS IN COMPLEX SHIFTED MORLET WAVELET (CSMW) BASED DEMODULATION OF DEFECTIVE ROLLING ELEMENT BEARINGS VIBRATION RESPONSE". International Journal of Wavelets, Multiresolution and Information Processing 07, n.º 04 (julio de 2009): 387–410. http://dx.doi.org/10.1142/s0219691309002982.
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Complex Shifted Morlet Wavelets (CSMW) present a number of advantages when used for the demodulation of the vibration response of defective rolling element bearings: (A) They present the optimally located window simultaneously in the time and in the frequency domains; (B) They allow for the maximal time-frequency resolution; (C) The magnitudes of the complex wavelet coefficients in the time domain lead directly to the required envelope; (D) They allow for the optimal selection of both the center frequency and the bandwidth of the requested filter. A Peak Energy criterion (P. E.) is proposed in this paper for the simultaneous automatic selection of both the center frequency and the bandwidth of the relevant wavelet window to be used. As shown in a number of application cases, this criterion presents a more effective behavior than other criteria used (Crest Factor, Kurtosis, Smoothness Index, Number of Peaks), since it combines the advantages of energy based criteria, with criteria characterizing the spikiness of the response.
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Moiseev, A. A. "Model-based estimation of radio parameters". Radio industry 28, n.º 3 (29 de agosto de 2018): 31–45. http://dx.doi.org/10.21778/2413-9599-2018-28-3-31-45.
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It’s proposed to use model-based approach for evaluation of radiation parameters observed by passive location facilities. This method is based on model parameters adjustment and interpretation of correspondent parameters values as experimental parameters evaluations. Evaluation adequacy criterion in this case is maximal probability of overlapping of experimental and model ranges of parameters. Preliminary objects selection can be based on frequency or/end directional characteristics of received signals. A possible selection criterion is based on discrimination conditions of frequency and time ranges. The appropriate analysis is performed on the basis of the extremal analysis enabling to select ranges corresponding to observed objects. Selected ranges are transformed into time functions to be analyzed by model-based method. Therewith the frequency analysis is performed on the assumption of linear frequency modulation of the signal observed. In its turn, the amplitude analysis is based on the passive location model. Parameters are selected either by Monte-Carlo method or by direct processing of equidistant grid nodes.
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Smerlak, M. "Neutral quasispecies evolution and the maximal entropy random walk". Science Advances 7, n.º 16 (abril de 2021): eabb2376. http://dx.doi.org/10.1126/sciadv.abb2376.
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Even if they have no impact on phenotype, neutral mutations are not equivalent in the eyes of evolution: A robust neutral variant—one which remains functional after further mutations—is more likely to spread in a large, diverse population than a fragile one. Quasispecies theory shows that the equilibrium frequency of a genotype is proportional to its eigenvector centrality in the neutral network. This paper explores the link between the selection for mutational robustness and the navigability of neutral networks. I show that sequences of neutral mutations follow a “maximal entropy random walk,” a canonical Markov chain on graphs with nonlocal, nondiffusive dynamics. I revisit M. Smith’s word-game model of evolution in this light, finding that the likelihood of certain sequences of substitutions can decrease with the population size. These counterintuitive results underscore the fertility of the interface between evolutionary dynamics, information theory, and physics.
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Pinho, João Pedro, Bruno Mezêncio, Desidério Cano Porras, Julio Cerca Serrão y Alberto Carlos Amadio. "Relationship Between Knee Extensors Power Output and Vastus Lateralis EMG Activation in Elderly Women: Influence of Mother Wavelet Selection". Open Sports Sciences Journal 10, n.º 1 (29 de diciembre de 2017): 263–71. http://dx.doi.org/10.2174/1875399x01710010263.
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Purpose:The main objective of this study was to compare frequency parameters produced by six mother wavelets pinpointing the most feasible to investigate electromyographic (EMG) parameters while producing knee extension power in elderly women. The influence of different load conditions in mother wavelet selection and power output were also analyzed.Methods:Thirteen sedentary elderly women (69.3 ± 4.1 years) took part in the study. Participants executed 6 repetitions of 3 load condition (30%, 50% and 70% of the maximal) with the concentric phase of the knee extension movement as quickly as possible. Kinematic data obtained by video analysis, an anthropometric model and Newtonian mechanics were used to calculate knee extensors’ power. A continuous wavelet analysis was used as a time-frequency transformation strategy of vastus lateralis and biceps femoris EMG data and six different mother wavelets were selected: Morlet; 4th, 8th and 44th order Daubechie, 4th order Coiflet and 5th order Symlet.Results:44th order Daubechie showed the highest maximal cross correlation value and no differences were seen between different mother wavelets and cross correlation at zero lag and in the lag variable. Although increased knee extensors peak power at higher loads were seen, no differences in vastus lateralis or biceps femoris root mean square values were obtained.Conclusion:44th order Daubechie mother wavelet was pinpointed as the most suitable to obtain EMG time-frequency parameters. We have also seen that different load conditions do not seem to have an influence on mother wavelet selection.
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Moiseev, A. A. "Improved rank selection algorithm". Radio industry (Russia) 31, n.º 1 (7 de abril de 2021): 37–44. http://dx.doi.org/10.21778/2413-9599-2021-31-1-37-44.
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Problem statement. A rank algorithm for selecting radio emission modes for operation in conditions of heterogeneity of sources and complex interference conditions, including the possible presence of mutual interference, is synthesized.Objective. The synthesis purpose is to ensure the independence of mode recognition from particular features of radio emission observation. Algorithm input is the primary signal processing result that includes such estimations as pulses durability, frequency and amplitude dynamics, and absolute variations. Primary decision statistics are formed using these values: observable signal base and relation variations of frequency and amplitude. Secondary statistics are formed based on primary ones using median and recursive or maximum and recursive smoothing. Each of the decision statistics in the multi-threshold procedure is transformed into a row of ranks, the size of which corresponds to the number of recognized modes. In aggregate, these lines form a ranking table (matrix) with colons representing recognized modes’ discrete descriptions. Fluent observation processing includes rank formation for used decision statistics. Mode recognition is performed either following a ranking table or using an additional voting procedure 2/3. An alternative approach consists of constructing the Manhattan mismatch metric of the current and reference ranks and making a decision on the criterion of the minimum mismatch metric.Results. Mode recognition performed on results of this comparison using unbalance metrics minimum criterion. Thresholds in frames of the ranking procedure are formed heuristically at ranking table formation. They are then used at fluent rank formation for observable modes. The performed numerical experiment shows that maximal and recursive filtration provides an errorless selection of all observable modes. This filtration represents the composition of maximum selection in sliding window and subsequent recursive first-order filtration. An additional advantage of this filtration is a simpler maximum selection in comparison with the median one. In perspective, it can provide increased operating speed.Practical implications. Performed consideration shows that rank selection is worthwhile at the observation of heterogeneous irradiation sources. Algorithm strength is decision simplicity in a complex situation. Additional algorithm advantage is the possibility of extending alternative irradiation modes and, hence, for more representative data sets.
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Gorbachova, Liudmyla O., Viktoria S. Prykhodkina y Borys F. Khrystiuk. "Spring flood frequency analysis in the Southern Buh River Basin, Ukraine". Journal of Geology, Geography and Geoecology 30, n.º 2 (17 de julio de 2021): 250–60. http://dx.doi.org/10.15421/112122.
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The river floods are among the most dangerous natural disasters in the world. Each year, the spring floods cause the significant material damage in the different countries, including Ukraine. Knowledge of trends in such floods, as well as their probabilistic forecast, is of great scientific and practical importance. In last decades, the decreasing phase of cyclical fluctuations of the maximum runoff of spring floods has been observed on the plain rivers of Ukraine, including the Southern Bug River. In addition, there is an increase in air temperature. So, the actual task is the determine the modern probable maximum discharges estimates of spring floods in the Southern Buh River Basin as well as their comparison with the estimates that were computed earlier. It gives an opportunity to reveal possible changes of the statistical characteristics and values of the probable maximum discharges, to analyze and to discuss the reasons for these changes. For the investigation, we used the time series of the maximum discharges of spring floods for 21 gauging stations in the Southern Buh River Basin since the beginning of the observations and till 2015. The method of the regression on the variable that is based on the data of analogues rivers was used to bringing up the duration of the time series and restoration of the gaps. In the study, the hydro-genetic methods for estimation of the homogeneity and stationarity of hydrological series, namely the mass curve, the residual mass curve and the combined graphs. The distributions of Kritskyi & Menkel and Pearson type III for the frequency analysis were used. It has been shown in this study that the maximum discharges of spring floods of time series are quasi-homogeneous and quasi-stationary. It is explained the presence in the observation series of only increasing and decreasing phases of cyclical fluctuations, their considerable duration, as well as the significant variability of the maximal flow. The series of maximal runoff of spring floods are very asymmetric, which significantly complicates the selection of analytical distribution curves. The updated current parameters of the maximal spring flood runoff have not changed significantly. It can be assumed that such characteristics have already become stable over time, as the series of maximal runoff of spring floods already have phases of increasing and decreasing of long-term cyclic fluctuations.
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Camporeale, Carlo y Peter J. Schmid. "Parametric resonance in unsteady watertable flow". Journal of Fluid Mechanics 768 (12 de marzo de 2015): 524–48. http://dx.doi.org/10.1017/jfm.2015.105.
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The stability of unsteady open-channel flow down an inclined plane is studied using an iterative approach based on the direct and adjoint stability equations combined with a physically justified energy measure. An efficient parametric resonance mechanism has been identified between the exogenous base-flow oscillations and the intrinsic frequencies of streamwise disturbance vortices. This resonance results in strong amplification over a substantial range of the governing parameters, favouring streamwise elongated structures. The optimal frequency for a maximal disturbance response can be efficiently approximated from simpler steady calculations; two frequency-selection criteria are given for this purpose. The analysis generalizes earlier work on steady watertable flow and provides an effective framework and starting point for further work on pattern formation in harmonically forced open-channel flows.
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LIU, HAN-BING y YU-BO JIAO. "APPLICATION OF GENETIC ALGORITHM-SUPPORT VECTOR MACHINE (GA-SVM) FOR DAMAGE IDENTIFICATION OF BRIDGE". International Journal of Computational Intelligence and Applications 10, n.º 04 (diciembre de 2011): 383–97. http://dx.doi.org/10.1142/s1469026811003215.
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A support vector machine (SVM) optimized by genetic algorithm (GA)-based damage identification method is proposed in this paper. The best kernel parameters are obtained by GA from selection, crossover and mutation, and utilized as the model parameters of SVM. The combined vector of mode shape ratio and frequency rate is used as the input variable. A numerical example for a simply supported bridge with five girders is provided to verify the feasibility of the method. Numerical simulation shows that the maximal relative errors of GA-SVM for the damage identification of single, two and three suspicious damaged elements is 1.84%. Meanwhile, comparative analyzes between GA-SVM and radical basis function (RBF), back propagation networks optimized by GA (GA-BP) were conducted, the maximal relative errors of RBF and GA-BP are 6.91% and 5.52%, respectively. It indicates that GA-SVM can assess the damage conditions with better accuracy.
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Pozuelo-Carrascosa, Diana P., Juan Manuel Carmona-Torres, José Alberto Laredo-Aguilera, Pedro Ángel Latorre-Román, Juan Antonio Párraga-Montilla y Ana Isabel Cobo-Cuenca. "Effectiveness of Respiratory Muscle Training for Pulmonary Function and Walking Ability in Patients with Stroke: A Systematic Review with Meta-Analysis". International Journal of Environmental Research and Public Health 17, n.º 15 (24 de julio de 2020): 5356. http://dx.doi.org/10.3390/ijerph17155356.
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Background: Neurological dysfunction due to stroke affects not only the extremities and trunk muscles but also the respiratory muscles. Aim: to synthesise the evidence available about the effectiveness of respiratory muscle training (RMT) to improve respiratory function parameters and functional capacity in poststroke patients. Methods: a systematic electronic search was performed in the MEDLINE, EMBASE, SPORTDiscus, PEDro and Web of Science databases, from inception to May 2020. Study selection and data extraction: randomised controlled trials (RCTs) that examined the effects of RMT versus non-RMT or sham RMT in poststroke patients. We extracted data about respiratory function, respiratory muscle strength and functional capacity (walking ability, dyspnea, balance, activities of daily life), characteristics of studies and features of RMT interventions (a type of RMT exercise, frequency, intensity and duration). Two reviewers performed study selection and data extraction independently. Results: nineteen RCTs met the study criteria. RMT improved the first second forced expiratory volume (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP) and walking ability (6 min walking test), but not Barthel index, Berg balance scale, and dyspnea. Conclusions: RMT interventions are effective to improve respiratory function and walking ability in poststroke patients.
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Chen, Xueliang, Baojia Chen y Zhengkun Chen. "Research on Fault Feature Extraction of Rolling Bearing Based on dFIF". Journal of Physics: Conference Series 2181, n.º 1 (1 de enero de 2022): 012044. http://dx.doi.org/10.1088/1742-6596/2181/1/012044.
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Abstract Aiming at the problems that the traditional adaptive mode decomposition method has low decomposition efficiency, poor ability of anti-mode mixing and decomposition accuracy, a rolling bearing fault feature recognition method based on direct fast iterative filtering (dFIF) and the crest factor of envelope spectrum is proposed. dFIF first decomposes the raw rolling bearing vibration signal into a set of intrinsic mode function (IMFs), then the optimal component is chosen based on the maximal crest factor of envelope spectrum, and finally the bearing fault characteristic frequency and its frequency multiplication are extracted using envelope demodulation analysis. It is demonstrated by relevant experimental data that the proposed method has efficient decomposition speed, accurate decomposition accuracy, and the accurate selection of effective components, and can effectively realize rolling bearing fault detection.
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Salh, Adeeb, Lukman Audah, Nor Shahida M Shah y Shipun A. Hamzah. "Adaptive Antenna Selection and Power Allocation in Downlink Massive MIMO Systems". International Journal of Electrical and Computer Engineering (IJECE) 7, n.º 6 (1 de diciembre de 2017): 3521. http://dx.doi.org/10.11591/ijece.v7i6.pp3521-3528.
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Massive multi-input, multi-output (MIMO) systems are an exciting area of study and an important technique for fifth-generation (5G) wireless networks that support high data rate traffic. An increased number of antenna arrays at the base station (BS) consumes more power due to a higher number of radio frequency (RF) chains, which cannot be neglected and becomes a technical challenge. In this paper, we investigated how to obtain the maximal data rate by deriving the optimal number of RF chains from a large number of available antenna arrays at the BS when there is equal power allocation among users. Meanwhile, to mitigate inter-user-interference and to compute transmit power allocation, we used the precoding scheme zero forcing beamforming (ZFBF). The achievable data rate is increased because the algorithm of ZFBF enables the choosing of the maximum power in relation to the optimal antenna selection. We conclude that the transmit power allocation allows the use of less number of RF chains which provides the maximum achievable data rate depending on the optimal RF chain at the BS.
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Yadnya, Made sutha, Suthami Ariessaputra y Natasya Dewi Astuti. "CHANNEL SELECTION SIMULATION WITH RAIN CONDITIONS WITH COMPARISON OF SIGNAL STRENGTH OF RECEIVER EXISTING 5G NETWORK FREQUENCY 2.3 GHZ". DIELEKTRIKA 10, n.º 2 (31 de agosto de 2023): 189–94. http://dx.doi.org/10.29303/dielektrika.v10i2.347.
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The 5G network has been used in Grand Prix 1 (GP-1) in Indonesia. In accordance with the permission granted by the Ministry of Communication and Information with a working frequency of below 900 MHZ, mid 2.3 GHz, and high 28 GHz. One of the advantages of 5G is that the download speed reaches 20 Gpbs per user using high frequencies. This study simulates by analyzing the effect of 5G network performance when there is rain attenuation which can reduce signal quality. Then a centralized RAN (C-RAN) architectural scenario is created when the BTS is dampened by rain for each of its links. Then calculating the rainfall data to become rain attenuation with ITU-R recommendations, the SNR values are obtained from 3 dBm to 20 dBm, the SNR values are used as input using the Maximal Ratio Combining method in order to reduce signal interference that occurs due to rain.
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Szulborski, Michał, Sebastian Łapczyński, Łukasz Kolimas, Łukasz Kozarek y Desire Dauphin Rasolomampionona. "Calculations of Electrodynamic Forces in Three-Phase Asymmetric Busbar System with the Use of FEM". Energies 13, n.º 20 (20 de octubre de 2020): 5477. http://dx.doi.org/10.3390/en13205477.
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Proper busbar selection based on analytical calculations is of great importance in terms of power grid functioning and its safe usage. Experimental tests concerning busbars are very expensive and difficult to be executed. Therefore, the great advantage for setting the valid parameters for busbar systems components are analytical calculations supported by FEM (finite element method) modelling and analysis. Determining electrodynamic forces in busbar systems tends to be crucial with regard to subsidiary, dependent parameters. In this paper analytical calculations of asymmetric three-phase busbar system were carried out. Key parameters, like maximal electrodynamic forces value, mechanical strength value, busbar natural frequency, etc., were calculated. Calculations were conducted with an ANSYS model of a parallel asymmetric busbar system, which confirmed the obtained results. Moreover, showing that a model based on finite elements tends to be very helpful in the selection of unusually-shaped busbars in various electrotechnical applications, like switchgear.
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Lou, Hao, Monicque M. Lorist y Karin S. Pilz. "Variability in the temporal dynamics of object-based attentional selection". PLOS ONE 18, n.º 11 (17 de noviembre de 2023): e0294252. http://dx.doi.org/10.1371/journal.pone.0294252.
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Our attention can be directed to specific locations in our visual field (space-based attention), or to specific objects (object-based attention). However, object-based attention tends to be less pronounced than space-based attention and can vary greatly between individuals. Here we investigated whether the low prevalence of object-based effects is related to variability in the temporal dynamics of attentional selection. We manipulated cue-to-target intervals from 50 to 600 ms in a two-rectangle discrimination task. Space- and object-based effects were measured at the group level and for individual participants. We used bootstrapping to highlight cue-to-target intervals with maximal space- and object-based effects, and fast Fourier transform (FFT) to investigate rhythmic sampling of locations within and between objects. Whereas overall, space-based effects were robust and stable across all cue-to-target intervals for most participants, object-based effects were small and were only found for a small subset of participants in the different cue-to-target intervals. In the frequency domain, only a small number of participants exhibited significant periodicities, prompting the need for further investigation and consideration. Overall, our study suggests variability in the temporal dynamics of object-based effects underlying their low prevalence, a finding that needs to be further investigated in future studies.
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Luo, Yu Feng, Yuan Shan Li y Xu Chen. "Analysis of Multiple Degrees of Freedom Vibration Isolation System Using the State Space Method". Advanced Materials Research 338 (septiembre de 2011): 431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.338.431.
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This papers deals with fast solving method of natural frequency and vibration isolation coefficient of multiple degrees of freedom vibration isolation system. In the foundation of a mathematical model of vibration motion differential equation, a new state space method is derived and presented. Through transforming the vibration isolation differential equations into the state space equations, it is convenient to facilitate the solution of vibration isolation coefficient of vibration isolation system of multiple degrees of freedom with damping, by using the state space method and the MATLAB/Simulink module. Simulation results showed the result is consistent with the theory result. Simulation results also showed that with the help of damping, the maximal vibration isolation coefficient of x direction is lowered from 90 to 3.2 in the 5.31Hz, which eliminate the resonance phenomenon. In y and z direction, the maximal vibration isolation coefficient is also decreased from 78 to 2.4 and from 210 to 2.35. The state space method can find further applications on the selection of vibration isolation system and the evaluation of vibration isolation efficiency.
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Zhou, Yuqing y Wei Xue. "A Multisensor Fusion Method for Tool Condition Monitoring in Milling". Sensors 18, n.º 11 (10 de noviembre de 2018): 3866. http://dx.doi.org/10.3390/s18113866.
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Tool fault diagnosis in numerical control (NC) machines plays a significant role in ensuring manufacturing quality. Tool condition monitoring (TCM) based on multisensors can provide more information related to tool condition, but it can also increase the risk that effective information is overwhelmed by redundant information. Thus, the method of obtaining the most effective feature information from multisensor signals is currently a hot topic. However, most of the current feature selection methods take into account the correlation between the feature parameters and the tool state and do not analyze the influence of feature parameters on prediction accuracy. In this paper, a multisensor global feature extraction method for TCM in the milling process is researched. Several statistical parameters in the time, frequency, and time–frequency (Wavelet packet transform) domains of multiple sensors are selected as an alternative parameter set. The monitoring model is executed by a Kernel-based extreme learning Machine (KELM), and a modified genetic algorithm (GA) is applied in order to search the optimal parameter combinations in a two-objective optimization model to achieve the highest prediction precision. The experimental results show that the proposed method outperforms the Pearson’s correlation coefficient (PCC) based, minimal redundancy and maximal relevance (mRMR) based, and Principal component analysis (PCA)-based feature selection methods.
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Alejos, Ana Vazquez, Manuel Garcia Sanchez y Iñigo Cuiñas. "Performance Analysis of Polarization Diversity for Indoor Scenarios at 41.4 GHz and 61.5 GHz". International Journal of Antennas and Propagation 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/681820.
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We present the radio channel experiments conducted in indoor scenarios to test the performance of a dual orthogonal polarization scheme in the single-branch receiver end of a mobile system with a centre frequency of 41.4 GHz and 61.5 GHz. The diversity gain has been obtained according to three main combination methods for an outage probability of 1%: signal selection, equal gain combining, and maximal ratio combining. Diversity gain calculated ranges from 0.25 to 4.5 dB, depending on the combination technique used, the radiation pattern, the scenario, and the frequency band. The spatial variation of the cross-polar discrimination factor (XPD) has been estimated. The XPD ranges from 31 dB to 34 dB at 41.4 GHz and between 26 dB and 29 dB for the 61.5 GHz band. From the gain and discrimination results, we evaluated the performance of this scheme to conclude its suitability as either a diversity technique for reducing signal fading, as the 41.4 GHz, or as a method for increasing the link capacity in the 61.5 GHz case.
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Xue, Han, Weicheng Zhang, Chao Ni y Xiping Lu. "Cross Product and Partitioned Filtering-Based Graham Convex Hull for Buoy Drifting Area Demarcating". Scientific Programming 2021 (29 de noviembre de 2021): 1–9. http://dx.doi.org/10.1155/2021/7713884.
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An improved Graham scan convex hull algorithm is designed using the convex hull region shrinkage algorithm and the sample selection decision algorithm. In the sorting of Graham scan convex hull algorithm, the cross-multiplication method is used instead of the operation of finding the polar angle, which avoids the high computational complexity of finding the inverse trigonometric function. When the polar angles are the same, that is, the two points are collinear, the points close to each other are deleted directly. Select the maximal horizontal ordinate point, minimal horizontal ordinate point, maximal longitudinal coordinate point, and minimal longitudinal coordinate point. Connect these points and obtain lines. The whole plane is divided into different regions. The points that are not on the convex hull are deleted, and the redundant points are removed. This can speed up the calculation of approximate convex hull boundary and shorten the time of convex hull calculation. The proposed algorithm is used for buoy drifting area demarcating. The offsets of the geometric center of the high-frequency position point and the distance from geometric center of high-frequency position of buoy to sinking stone are calculated. The experimental results show that the new algorithm can effectively accelerate the convex hull calculation. We use the convex hull process to compute the area of the drifting buoy position and discover that the drift area of the port hand buoy is similar. The drift area of the port hand buoys is similar. The drift area of the port hand buoy is greater than that of the port hand buoy.
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Dumont-Lagacé, Maude, Albert Feghaly, Gabrielle Thauvette, Marie-Christine Meunier, William Lemieux, Diane Fournier, Lucie Richard, Sébastien Lemieux, Guy Sauvageau y Sandra Cohen. "Abstract 25 ECTmatch: Optimizing Small-Scale Cord Blood Banking Through HLA Analysis". Stem Cells Translational Medicine 11, Supplement_1 (1 de septiembre de 2022): S30. http://dx.doi.org/10.1093/stcltm/szac057.025.
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Abstract Introduction Cord blood (CB) banks have had to rely on large inventories of CB units to try to serve the largest possible proportion of the population, all the while prioritizing collection of non-Caucasian ethnic groups. However, due to the high linkage disequilibrium of HLA genes and the high frequency of several HLA alleles in the population, CB banks contain hundreds of CB units that could be matched to the same patients, making the inventory somewhat redundant from a clinical standpoint. Objective ExCellThera developed ECTmatch, an algorithm dedicated to optimizing the selection of CB units based on in-depth HLA analysis in order to maximize the efficiency of the bank to suitably match the largest proportion of subjects within a small pool of donors. Methods The performance of ECTmatch was evaluated in a simulation aiming to select 100 CB units from the Héma-Québec CB bank that satisfied an arbitrary minimal cell content criteria of 120 × 107 TNC and 6 × 106 CD34+ cells (n = 2,987). Selection was performed to optimize matching for the Quebec population, with a minimal HLA-match of 5/8 for HLA-A, -B, -C, and -DRB1. Results ECTmatch provides a suitably matched donor for 71.5% of the Quebec population, compared with only 45.0% (±2.4%) with random selection. Because patients who require a CB transplant tend to have rarer HLAs, the performance of ECTmatch was evaluated for this specific subset of patients (n = 62). Again, ECTmatch outperformed random selection, by providing a donor for 54.8% of patients, compared with only 29.9% with random selection. Finally, while ECTmatch was developed to optimize CB selection specifically for the Quebec population, it still outperformed random selection for subjects from the other Canadian provinces or the USA. Discussion By selecting CB units based on HLA profiles, ECTmatch allows the creation of a highly useful inventory with a very low number of CB units. This approach to small-scale CB banking can be adapted to different population subsets and could be used to select a subset of CB units for pre-release for immediate clinical availability or for the creation of a pre-expanded CB inventory with maximal population coverage.
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Weber, Kaye, Sherry E. Courtney, Kee H. Pyon, Gordon Y. Chang, Paresh B. Pandit y Robert H. Habib. "Detecting lung overdistention in newborns treated with high-frequency oscillatory ventilation". Journal of Applied Physiology 89, n.º 1 (1 de julio de 2000): 364–72. http://dx.doi.org/10.1152/jappl.2000.89.1.364.
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Positive airway pressure (Paw) during high-frequency oscillatory ventilation (HFOV) increases lung volume and can lead to lung overdistention with potentially serious adverse effects. To date, no method is available to monitor changes in lung volume (ΔVl) in HFOV-treated infants to avoid overdistention. In five newborn piglets (6–15 days old, 2.2–4.2 kg), we investigated the use of direct current-coupled respiratory inductive plethysmography (RIP) for this purpose by evaluating it against whole body plethysmography. Animals were instrumented, fitted with RIP bands, paralyzed, sedated, and placed in the plethysmograph. RIP and plethysmography were simultaneously calibrated, and HFOV was instituted at varying Paw settings before (6–14 cmH2O) and after (10–24 cmH2O) repeated warm saline lung lavage to induce experimental surfactant deficiency. Estimates of ΔVl from both methods were in good agreement, both transiently and in the steady state. Maximal changes in lung volume (ΔVl max) from all piglets were highly correlated with ΔVl measured by RIP (in ml) = 1.01 × changes measured by whole body plethysmography − 0.35; r 2 = 0.95. Accuracy of RIP was unchanged after lavage. Effective respiratory system compliance (Ceff) decreased after lavage, yet it exhibited similar sigmoidal dependence on ΔVl max pre- and postlavage. A decrease in Ceff (relative to the previous Paw setting) as ΔVl max was methodically increased from low to high Paw provided a quantitative method for detecting lung overdistention. We conclude that RIP offers a noninvasive and clinically applicable method for accurately estimating lung recruitment during HFOV. Consequently, RIP allows the detection of lung overdistention and selection of optimal HFOV from derived Ceff data.
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Jürgens, Tim P., Jean Schoenen, Jørgen Rostgaard, Søren Hillerup, Miguel JA Láinez, Alexandre T. Assaf, Arne May y Rigmor H. Jensen. "Stimulation of the sphenopalatine ganglion in intractable cluster headache: Expert consensus on patient selection and standards of care". Cephalalgia 34, n.º 13 (16 de abril de 2014): 1100–1110. http://dx.doi.org/10.1177/0333102414530524.
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Context and overview Chronic cluster headache (CCH) is a debilitating headache disorder with a significant impairment of the patients' lives. Within the past decade, various invasive neuromodulatory approaches have been proposed for the treatment of CCH refractory to standard preventive drug, but only very few randomized controlled studies exist in the field of neuromodulation for the treatment of drug-refractory headaches. Based on the prominent role of the cranial parasympathetic system in acute cluster headache attacks, high-frequency sphenopalatine ganglion (SPG) stimulation has been shown to abort ongoing attacks in some patients in a first small study. As preventive effects of SPG-stimulation have been suggested and the rate of long-term side effects was moderate, SPG stimulation appears to be a promising new treatment strategy. Aims and conclusion As SPG stimulation is effective in some patients and the first commercially available CE-marked SPG neurostimulator system has been introduced for cluster headache, patient selection and care should be standardized to ensure maximal efficacy and safety. As only limited data have been published on SPG stimulation, standards of care based on expert consensus are proposed to ensure homogeneous patient selection and treatment across international headache centres. Given that SPG stimulation is still a novel approach, all expert-based consensus on patient selection and standards of care should be re-reviewed when more long-term data are available.
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Huang, Weijian, Qi Song y Yuan Huang. "Two-Stage Short-Term Power Load Forecasting Based on SSA–VMD and Feature Selection". Applied Sciences 13, n.º 11 (5 de junio de 2023): 6845. http://dx.doi.org/10.3390/app13116845.
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Short-term power load forecasting is of great significance for the reliable and safe operation of power systems. In order to improve the accuracy of short-term load forecasting, for the problems of random fluctuation in load and the complexity of load-influencing factors, this paper proposes a two-stage short-term load forecasting method, SSA–VMD-LSTM-MLR-FE (SVLM–FE) based on sparrow search algorithm (SSA), to optimize variational mode decomposition (VMD) and feature engineering (FE). Firstly, an evaluation criterion on the loss of VMD decomposition is proposed, and SSA is used to find the optimal combination of parameters for VMD under this criterion. Secondly, the first stage of forecasting is carried out, and the different components obtained from SSA–VMD are predicted separately, with the high-frequency components input to a long short-term memory network (LSTM) for forecasting and the low-frequency components input to a multiple linear regression model (MLR) for forecasting. Finally, the forecasting values of the components obtained in the first stage are input to the second stage for error correction; factors with a high degree of influence on the load are selected using the Pearson correlation coefficient (PCC) and maximal information coefficient (MIC), and the load value at the moment that has a great influence on the load value at the time to be predicted is selected using autocorrelation function (ACF). The forecasting values of the components are fused with the selected feature values to construct a vector, which is fed into the fully connected layer for forecasting. In this paper, the performance of SVLM–FE is evaluated experimentally on two datasets from two places in China. In Place 1, the RMSE, MAE, and MAPE are 128.169 MW, 102.525 MW, and 1.562%, respectively; in Place 2, the RMSE, MAE, and MAPE are 111.636 MW, 92.291 MW, and 1.426%, respectively. The experimental results show that SVLM–FE has high accuracy and stability.
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Bhardwaj, Ananya, Ahmed Allam, Alper Erturk y Karim G. Sabra. "Optimizing wireless acoustic energy harvesting and communication with passive markers underwater". Journal of the Acoustical Society of America 153, n.º 3_supplement (1 de marzo de 2023): A345. http://dx.doi.org/10.1121/10.0019099.
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To enhance functionality of Acoustic Identification Tags (AID), passive markers designed as landmarks for Autonomous Underwater Vehicles (AUVs) [Satish et al., JASA 149 (2021)], the development of an accompanying battery free active communication platform was explored [Bhardwaj et al., JASA 152, 4 (2022)]. This platform utilizes custom piezoelectric transducers impedance matched for broadband operation, enabling concurrent acoustic energy harvesting and fast backscatter communication [Allam et al., SPIE 31, 9 (2022)]. The combination of these active and passive devices can improve AUV localization and information transfer for specific applications such as short-range search missions or AUV homing and docking. The design of this platform for underwater operations requires a balance of parameters such as center frequency and piezoelectric element dimensions to achieve a high range of operation, power efficiency and data rates, while minimizing attenuation and spreading losses challenges. The design process for piezo selection, acoustic and electrical impedance matching, transducer casing design, and the experimental evaluation of the chosen 350 kHz design will be discussed. This approach was validated experimentally to quantify performance metrics such as the maximal range, data rates using various standard communication such as Frequency Shift Keying (FSK) and Amplitude Modulation (AM).
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Merwad, Ezzat A., Magdy M. AbdElftah, Said Abdelmonem, Elham M. Hasan y Mohammad W. El-Anwar. "Subepithelial hydrodissection improves voice outcome of microflap surgery for vocal cord cyst". Egyptian Journal of Otolaryngology 35, n.º 1 (enero de 2019): 51–55. http://dx.doi.org/10.4103/ejo.ejo_75_18.
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Abstract Objective The aim was to evaluate voice outcomes of microflap surgery with subepithelial infiltration for vocal fold cysts and to compare voice outcomes of microsurgery with and without subepithelial infiltration for vocal fold cysts. Patients and Methods This study was conducted on patients with vocal folds cysts. Patients who met selection criteria were divided into two groups: group A was operated by microflap surgery with subepithelial infiltration, and group B was operated by microflap surgery without subepithelial infiltration. Results Within the included 24 patients (12 in each group), a significant improvement of average fundamental frequency/fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, maximal phonation time (MPT), and dysphonia was detected postoperatively in group A (with subepithelial infiltration), with 58.3% of patients resorted to grade 0 dysphonia. Statistically significant improvement of MPT and dysphonia was registered after intervention in group B (without hydrodissection). However, average fundamental frequency/fundamental frequency, jitter, shimmer, and harmonic to noise ratio (HNR) showed nonsignificant improvement after intervention. It was clear that dysphonia improved significantly more in hydrodissection group than nonhydrodissection group (P=0.0063). However, there was no significant difference in postoperative MPT (P=0.3138). Conclusion Subepithelial infiltration is beneficial during microflap surgery for vocal fold cysts, with statistically significant better voice results. Therefore, we recommend using this technique during microflap surgery to enhance vocal outcomes; however, further studies are needed on a large number of patients and for a prolonged period of follow-up.
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Ismailova, Aigul, Sailaubai Onayev y Aizhan Ismailova. "CRITERIA OF OCCUPATIONAL FITNESS FOR WORKERS OF COAL PRODUCTION EXTREME PROFESSIONS". CBU International Conference Proceedings 1 (30 de junio de 2013): 323–30. http://dx.doi.org/10.12955/cbup.v1.52.
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In recent years issues of personal suitability for specific workplace (or career suitability) using complex methodological approaches were widely discussed in various fields of economy. This included studies of individual properties of neural system, personality, mental processes, cortico-subcortical relationships, autonomic responses, which characterize the degree of stress imposed upon a human's body. Specific working conditions in coal mines, characterized by a complex of unfavorable factors, place increased demands on psychofunctional conditions of miners’ bodies. Certain general properties of body should be studied and be critically important for selection of extreme profession. Intensification of industrial production, growth requirements for quantity and quality of work and level of training brings stricter requirements of professional competences. Competences are especially important for those occupations in which the discrepancy between physiological capacity of a body is associated with potential health damage and life threatening risks. We have developed criteria for suitability applicable to the preparation of young professionals to work in extreme conditions of the coal production. Use of a complex psychophysiological indicators of professional competence of body work, will increase efficiency, reliability and enable trouble-free carrier. The most informative psychophysiological parameters are Breathing capacity, Capacity of forced breathing, Maximal volume speed, Maximal ventilation of lungs, Systolic arterial pressure, Diastolic arterial pressure, Frequency of systole, Reactive uneasiness and Individual uneasiness.
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Uyar, Osman Murat, Francoise Sadler, Eva-Maria Konrad y Faik Gelisken. "Impact of OCT scan-patterns in identifying morphological features of lamellar macular holes and macular pseudoholes". International Journal of Ophthalmology 15, n.º 7 (18 de julio de 2022): 1089–94. http://dx.doi.org/10.18240/ijo.2022.07.08.
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AIM: To evaluate the impact of the optical coherence tomography (OCT) scan patterns on the detection of the features associated with lamellar macular hole (LMH) and macular pseudohole (MPH). METHODS: This is a retrospective analysis of 100 consecutive eyes with LMH (n=41) and MPH (n=59) having at least three of the following OCT features, which include mandatory criteria for the diagnosis of LMH and MPH: Epiretinal membrane, epiretinal proliferation, verticalization, intraretinal cystoid spaces, foveoschisis, irregular foveal contour, foveal cavity with undermined edges, and ellipsoid line disruption. Primary outcome measurement was the detection frequency of the features in three different OCT scan patterns: 1) volume scan; 2) six radial scans (R6); and 3) vertical and horizontal radial scans (R2). RESULTS: Of the total eight features, the maximal detection frequency was found as 4.45±1.45, 4.35±1.47, and 3.70±1.59, by the volume, R6 and R2, respectively. R2 was inferior to the other patterns in detection of the total features (P<0.001), whereas R6 and volume patterns were found comparable (P=0.312). CONCLUSION: The physician should be aware that the selection of the OCT-scan pattern may influence the detection of mandatory morphological criteria for the diagnosis of LMH and MPH.
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Chen, Yan y Chunchun Hu. "Hourly PM2.5 Concentration Prediction Based on Empirical Mode Decomposition and Geographically Weighted Neural Network". ISPRS International Journal of Geo-Information 13, n.º 3 (2 de marzo de 2024): 79. http://dx.doi.org/10.3390/ijgi13030079.
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Accurate prediction of fine particulate matter (PM2.5) concentration is crucial for improving environmental conditions and effectively controlling air pollution. However, some existing studies could ignore the nonlinearity and spatial correlation of time series data observed from stations, and it is difficult to avoid the redundancy between features during feature selection. To further improve the accuracy, this study proposes a hybrid model based on empirical mode decomposition (EMD), minimal-redundancy-maximal-relevance (mRMR), and geographically weighted neural network (GWNN) for hourly PM2.5 concentration prediction, named EMD-mRMR-GWNN. Firstly, the original PM2.5 concentration sequence with distinct nonlinearity and non-stationarity is decomposed into multiple intrinsic mode functions (IMFs) and a residual component using EMD. IMFs are further classified and reconstructed into high-frequency and low-frequency components using the one-sample t-test. Secondly, the optimal feature subset is selected from high-frequency and low-frequency components with mRMR for the prediction model, thus holding the correlation between features and the target variable and reducing the redundancy among features. Thirdly, the residual component is predicted with the simple moving average (SMA) due to its strong trend and autocorrelation, and GWNN is used to predict the high-frequency and low-frequency components. The final prediction of the PM2.5 concentration value is calculated by an artificial neural network (ANN) composed of the predictive values of each component. PM2.5 concentration prediction experiments in three representational cities, such as Beijing, Wuhan, and Kunming were carried out. The proposed model achieved high accuracy with a coefficient of determination greater than 0.92 in forecasting PM2.5 concentration for the next 1 h. We compared this model with four baseline models in forecasting PM2.5 concentration for the next few hours and found it performed the best in PM2.5 concentration prediction. The experimental results indicated the proposed model can improve prediction accuracy.
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Di Pede, Francesco, Francesco Pistelli, Giovanni Viegi, Paolo Paoletti, Alessandro Celi, Laura Carrozzi, Mariella Vellutini, Giuseppe Pistelli y Carlo Giuntini. "Inclusion of Peak Expiratory Flow for Selection of the 'Best' Forced Vital Capacity Manoeuvre". Canadian Respiratory Journal 3, n.º 5 (1996): 301–8. http://dx.doi.org/10.1155/1996/365275.
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OBJECTIVE:To assess four different criteria for selecting the 'best' forced vital capacity (FVC) manoeuvre to be used for clinical diagnostic purposes.DESIGN:Criterion standard.SETTING:General population survey performed in 1980-82.PATIENTS:One thousand, two hundred and eighty-three subjects (age range eight to 64 years) were first stratified into five mutually exclusive groups according to the following criteria: simultaneous largest FVC, forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) (group 1; n=481); isolated largest FVC (group 2; n=223); isolated largest FEV1(group 3; n=144); isolated largest PEF (group 4; n=299); and overlapping criteria (group 5; n=136).INTERVENTION:Subjects performed spirometry following American Thoracic Society (ATS) protocol and filled out a standardized respiratory questionnaire.MAIN OUTCOME MEASURES:Spirograms were analyzed by examining the frequency of spirometry abnormalities with regard to the presence of respiratory symptoms, first within mutually exclusive groups of subjects and then within the whole sample. The hypothesis of the role of PEF in 'best test' selection was formulated after data collection.MAIN RESULTS:When the isolated largest PEF criterion was used, the following data were obtained: the highest prevalence of spirometric abnormalities for each FVC parameter in each mutually exclusive group; the highest predictive value for mean and instantaneous expiratory flows in separating symptomatic from asymptomatic subjects; and finally, using the whole sample, higher levels of sensitivity and similar specificity to other criteria for all test parameters (all over 90%, except for PEF).CONCLUSIONS:While maintaining the current ATS criteria of acceptability and variability for FVC trials, it is proposed that the curve that better reflects maximal expiratory effort, ie, that with the largest PEF, be recorded and analyzed for spirometric variables.
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Garcia-Effron, Guillermo. "Rezafungin—Mechanisms of Action, Susceptibility and Resistance: Similarities and Differences with the Other Echinocandins". Journal of Fungi 6, n.º 4 (1 de noviembre de 2020): 262. http://dx.doi.org/10.3390/jof6040262.
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Rezafungin (formerly CD101) is a new β-glucan synthase inhibitor that is chemically related with anidulafungin. It is considered the first molecule of the new generation of long-acting echinocandins. It has several advantages over the already approved by the Food and Drug Administration (FDA) echinocandins as it has better tissue penetration, better pharmacokinetic/phamacodynamic (PK/PD) pharmacometrics, and a good safety profile. It is much more stable in solution than the older echinocandins, making it more flexible in terms of dosing, storage, and manufacturing. These properties would allow rezafungin to be administered once-weekly (intravenous) and to be potentially administered topically and subcutaneously. In addition, higher dose regimens were tested with no evidence of toxic effect. This will eventually prevent (or reduce) the selection of resistant strains. Rezafungin also has several similarities with older echinocandins as they share the same in vitro behavior (very similar Minimum Inhibitory Concentration required to inhibit the growth of 50% of the isolates (MIC50) and half enzyme maximal inhibitory concentration 50% (IC50)) and spectrum, the same target, and the same mechanisms of resistance. The selection of FKS mutants occurred at similar frequency for rezafungin than for anidulafungin and caspofungin. In this review, rezafungin mechanism of action, target, mechanism of resistance, and in vitro data are described in a comparative manner with the already approved echinocandins.
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Pariente, Nonia, Antero Airaksinen y Esteban Domingo. "Mutagenesis versus Inhibition in the Efficiency of Extinction of Foot-and-Mouth Disease Virus". Journal of Virology 77, n.º 12 (15 de junio de 2003): 7131–38. http://dx.doi.org/10.1128/jvi.77.12.7131-7138.2003.
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ABSTRACT RNA viruses replicate near the error threshold for maintenance of genetic information, and an increase in mutation frequency during replication may drive RNA viruses to extinction in a process termed lethal mutagenesis. This report addresses the efficiency of extinction (versus escape from extinction) of foot-and-mouth disease virus (FMDV) by combinations of the mutagenic base analog 5-fluorouracil (FU) and the antiviral inhibitors guanidine hydrochloride (G) and heparin (H). Selection of G- or H-resistant, extinction-escape mutants occurred with low-fitness virus only in the absence of FU and with high-fitness virus with some mutagen-inhibitor combinations tested. The combination of FU, G, and H prevented selection of extinction-escape mutants in all cases examined, and extinction of high-fitness FMDV could not be achieved by equivalent inhibitory activity exerted by the nonmutagenic agents. The G-resistant phenotype was mapped in nonstructural protein 2C by introducing the relevant mutations in infectious cDNA clones. Decreases in FMDV infectivity were accompanied by modest decreases in the intracellular and extracellular levels of FMDV RNA, maximal intracellular concentrations of FU triphosphate, and a decrease in the intracellular concentrations of UTP. In addition to indicating a key participation of mutagenesis in virus extinction, the results suggest that picornaviruses provide versatile experimental systems to approach the problem of extinction failure associated with inhibitor-escape mutants during treatments based on enhanced mutagenesis.
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Rakhmanin, U. A., S. E. Shibanov y Sergey V. Kozulya. "Choice of sanitary-indicative microorganisms for the assessment of the safety of split-systems". Hygiene and sanitation 95, n.º 3 (28 de octubre de 2019): 296–301. http://dx.doi.org/10.18821/0016-9900-2016-95-3-296-301.
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Purpose of work is a compilation of data about the microflora which colonizes a split-system, with the aim of selection of sanitary-indicative microorganisms, whose presence in the sample would indicate to the need for cleaning and disinfection of split-systems. Materials and methods. In the article there were used data of five years author’s scientific inquiry, related to the prevention of respiratory diseases, associated with the usage of a local air conditioning systems. We also use the data from the literature. Results. For selection of “indicative” microorganisms, we proposed the usage of nine criteria, each of them have numeric value from 0 to 3 points (risk for health, prevalence rate of the disease, epidemiological link, speed of split system’s colonization, difficulty of cultivation, resistance in the environment, resistance to disinfectants, frequency of detection in home air conditioning systems, frequency of detection in air conditioning systems of public buildings). After the calculation Pseudomonas aeruginosa and Staphylococcus aureus received maximal score (20 points). Therefore, these two types of bacteria are indicative microorganisms. The detection of these microorganisms in split systems will indicate to the contamination of air-conditioning system. This microflora also is a criterion of cleaning and disinfection quality - presence of these microorganisms in the samples after this process will mean that the processing of air conditioning systems was performed poorly. Conclusions. Split systems are very faster colonized by conditionally pathogenic and pathogenic microflora. To prevent the possible hazard for population’s health it is necessary to develop the normative base, according to which sanitary-and-hygienic control over the split-systems working must be carried out. Proposed criteria suggest that Pseudomonas aeruginosa and Staphylococcus aureus are indicative microorganisms, and it’s identification in the air-conditioning system would mean risk for health and necessity for cleaning and disinfection.
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Strong, Beverly SI, Amanda E. Lee, Tess J. Newkold, Lucas E. Turner y Aimen F. Shaaban. "Prenatal Allospecific Tolerance Is Characterized By Early Treg Expansion and a Surprisingly Slow Pace for Teff Clonal Deletion". Blood 126, n.º 23 (3 de diciembre de 2015): 3070. http://dx.doi.org/10.1182/blood.v126.23.3070.3070.
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Abstract Prenatal transplantation capitalizes on the unique fetal environment, allowing for life-long engraftment of allogeneic stem cells without the need for harsh conditioning regimens. A prerequisite for stable engraftment of allogeneic cells likely requires the negative selection of donor-specific host effector T cells (Teff) and the support of donor-specific regulatory T cells (Tregs). However, little is known about the interplay between these cell types during development. The purpose of this study was to characterize the dynamic relationship between donor-specific Teff and Tregs as they emerge during development. Prenatal allogeneic chimeras were established by in utero transplantation of E14 fetal liver light density cells into age-matched allogeneic fetal recipients (Balb/c to B6 or B6 to Balb/c). In this model, immature T cells from B6 mice expressing TCRv-beta-5, 11, and 12 are negatively selected by mtv-8 superantigen complexed with I-E class MHC II on Balb/c cells. As alpha/beta TCR rearrangement does not occur until E16, this established transplantation model allows for alloantigen to be present from the earliest stages of thymic selection. Kinetic analysis of donor-specific T cell populations was performed in peripheral blood paired with in depth analysis in thymus and spleen in control and chimeric mice. Negative selection of donor-specific Teff cells occurs at an unexpectedly slow pace in Balb/c to B6 prenatal chimeras. Donor-specific CD4 and CD8 Teff are significantly decreased in frequency at 4 weeks of age but do not reach maximal deletion until 12 weeks of age (TCRv-beta-5 data shown in Figure A). Further analysis demonstrated that this slow elimination of donor-specific Teff was paired with an early increase in the frequency of donor-specific Tregs at 4 weeks of age (TCRv-beta-5 data shown in Figure B.) This increase in donor-specific Tregs likely occurred as a result of peripheral expansion as there was no change in the frequency of donor-specific Tregs in the thymus (Figure B) and no change in the frequency of these cells that expressed the markers of thymically derived natural Tregs neuropilin-1 or helios (data not shown). In agreement with this hypothesis, donor-specific splenic Tregs incorporated BrdU at a higher rate than other Tregs in young mice indicating a potential expansion of donor-specific Tregs in the periphery (TCRv-beta-5 data shown in Figure C.) Collectively, these data demonstrate that prenatal transplantation is characterized by: 1) a surprisingly slow reduction of donor-specific Teff subsets; 2) an early expansion of donor-specific Tregs. Further studies will explore the role of donor-specific Tregs in controlling early immunity to prenatally encountered antigens. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.
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Zhang, Tianhe C., John J. Janik y Warren M. Grill. "Modeling effects of spinal cord stimulation on wide-dynamic range dorsal horn neurons: influence of stimulation frequency and GABAergic inhibition". Journal of Neurophysiology 112, n.º 3 (1 de agosto de 2014): 552–67. http://dx.doi.org/10.1152/jn.00254.2014.
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Spinal cord stimulation (SCS) is a clinical therapy for chronic, neuropathic pain, but an incomplete understanding of the mechanisms underlying SCS contributes to the lack of improvement in SCS efficacy over time. To study the mechanisms underlying SCS, we constructed a biophysically based network model of the dorsal horn circuit consisting of interconnected dorsal horn interneurons and a wide-dynamic range (WDR) projection neuron and representations of both local and surround receptive field inhibition. We validated the network model by reproducing cellular and network responses relevant to pain processing including wind-up, A fiber-mediated inhibition, and surround receptive field inhibition. We then simulated the effects of SCS on the activity of the WDR projection neuron and found that the response of the model WDR neuron to SCS depends on the SCS frequency; SCS frequencies of 30–100 Hz maximally inhibited the model WDR neuron, while frequencies under 30 Hz and over 100 Hz excited the model WDR neuron. We also studied the impacts on the effects of SCS of loss of inhibition due to the loss of either GABA or KCC2 function. Reducing the influence of local and surround GABAergic interneurons by weakening their inputs or their connections to the WDR neuron and shifting the anionic reversal potential of the WDR neurons upward each reduced the range of optimal SCS frequencies and changed the frequency at which SCS had a maximal effect. The results of this study provide insights into the mechanisms of SCS and pave the way for improved SCS parameter selection.
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Muccino, David R., Alyn H. Morice, Surinder S. Birring, Peter V. Dicpinigaitis, Ian D. Pavord, Christopher Assaid, Huub Jan Kleijn et al. "Design and rationale of two phase 3 randomised controlled trials (COUGH-1 and COUGH-2) of gefapixant, a P2X3 receptor antagonist, in refractory or unexplained chronic cough". ERJ Open Research 6, n.º 4 (octubre de 2020): 00284–2020. http://dx.doi.org/10.1183/23120541.00284-2020.
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BackgroundWe present study designs, dose selection and preliminary patient characteristics from two phase 3 clinical trials of gefapixant, a P2X3 receptor antagonist, in refractory chronic cough (RCC) or unexplained chronic cough (UCC).MethodsCOUGH-1 (NCT03449134) and COUGH-2 (NCT03449147) are randomised, placebo-controlled, double-blind, parallel-group trials in subjects with RCC or UCC (age ≥18 years; cough duration ≥1 year; Cough Severity Visual Analogue Scale score ≥40 mm). The primary efficacy study periods are 12 weeks (40-week extension; COUGH-1) and 24 weeks (28-week extension; COUGH-2). Interventions include placebo, gefapixant 15 mg and gefapixant 45 mg (1:1:1 ratio). The primary efficacy endpoints are average 24-h cough frequency at Week 12 (COUGH-1) and Week 24 (COUGH-2). Awake cough frequency, patient-reported outcomes and responder analyses are secondary endpoints.ResultsThe doses of 45 mg (to provide maximal efficacy and acceptable tolerability) and 15 mg (to provide acceptable efficacy and improved tolerability) were selected based on phase 1 and 2 studies. In COUGH-1, 730 participants have been randomised and treated; 74% are female with mean age of 59 years (39% over 65 years), and mean baseline duration of cough of 11.5 years. In COUGH-2, 1314 participants have been randomised and treated; 75% are female with mean age of 58 years (33% over 65 years), and mean baseline duration of cough of 11.1 years.ConclusionsThese global studies include participants with baseline characteristics consistent with previous RCC and UCC studies and will inform the efficacy and safety profile of gefapixant in the treatment of patients with RCC and UCC.
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Hassan, Mazlina Mansor, Kasumawati Lias, Norlida Buniyamin, Mohamad Zulkarnaen Ahmad Narihan, Bibi Sarpinah Sheikh Naimullah y Dzufi Iszura Ispawi. "SAR Analysis Using Various Substrates of Microstrip Antenna for Breast Cancer Hyperthermia Treatment". Journal of Physics: Conference Series 2622, n.º 1 (1 de octubre de 2023): 012006. http://dx.doi.org/10.1088/1742-6596/2622/1/012006.
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Abstract Hyperthermia is an alternative technique used to treat breast cancer using high heat, around 41°C to 45°C, to denature cancer tissue into necrotic tissue. It can work independently or in adjuvant with other conventional methods. The design of an antenna with a suitable substrate is essential for the applicator to transmit maximal heat to the intended area and distribute the heat uniformly on the treated tissues. Therefore, the inset feed microstrip antenna is design with five different substrates, simulated, analyzed, and their performance is compared to get the best substrate. The substrates used include Rogers Duroid RT5880, Rogers RO4003, FR4, Alumina and Rogers RO3010. SEMCAD X 14.8.4 software is used to design, simulate and generate SAR. RT5880 and RO4003 show better SAR distribution and focus position distance (FPD), which can be further examined for future research. 2450 MHz, 915 MHz and 434 MHz frequencies are compared to find the most suitable frequency to apply with the applicator. A 915 MHz frequency shows better performance which can penetrate more toward the cancerous areas. However, there are several deficiencies such as difficulty in controlling FPD, wide unwanted hotspot and massive skin burn problem, that needs to be improved to provide less adverse health effects due to the execution of hyperthermia treatment. The selection of suitable substrates can help reduce the deficiencies and improve the effectiveness of the hyperthermia technique. The estimated period is within 2 hours to 3.6 hours to achieve sufficient heating to destroy the cancerous cells.
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Jargin, Sergei V. "Exaggeration of consequences of low-dose radiation exposures with special reference to cataracts". Imaging and Radiation Research 6, n.º 1 (23 de enero de 2024): 3387. http://dx.doi.org/10.24294/irr.v6i1.3387.
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Publications overestimating the medical and ecological sequels of a slight anthropogenic increase in the radiation background have been reviewed recently with examples of different organs and pathological conditions. The overestimation contributed to the strangulation of atomic energy. The use of nuclear energy for electricity production is on the agenda today due to the increasing energy needs of humankind. Apparently, certain scientific writers acted in the interests of fossil fuel producers. Health risks and environmental damage are maximal for coal and oil, lower for natural gas, and much lower for atomic energy. This letter is an addition to previously published materials, this time focused on studies of cataracts in radiation-exposed populations in Russia. Selection and self-selection bias are of particular significance. Apparently, the self-reporting rate correlates with dose estimates and/or with professional awareness about radiation-related risks among nuclear workers or radiologic technologists, the latter being associated with their work experience/duration and hence with the accumulated dose. Individuals informed of their higher doses would more often seek medical advice and receive more attention from medics. As a result, lens opacities are diagnosed in exposed people earlier than in the general population. This explains dose-effect correlations proven for the incidence of cataracts but not for the frequency of cataract surgeries. Along the same lines, various pathological conditions are more often detected in exposed people. Ideological bias and the trimming of statistics have not been unusual in the Russian medical sciences. It is known that ionizing radiation causes cataracts; however, threshold levels associated with risks are understudied. In particular, thresholds for chronic and fractionated exposures are uncertain and may be underestimated.
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Martens, Holger. "Transition Period of the Dairy Cow Revisited: I. Homeorhesis and Its Changes by Selection and Management". Journal of Agricultural Science 12, n.º 3 (15 de febrero de 2020): 1. http://dx.doi.org/10.5539/jas.v12n3p1.
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The transition period of the dairy cow involves the end of pregnancy, parturition, and the onset of lactation. Multifaceted and rapid changes occur during this time, and in particular, the increase of milk secretion requires the large-scale reorientation of metabolism. The underlying mechanisms of this metabolic regulation are collectively named homeorhesis, a process that governs milk production during this phase and that exhibits (A) a chronic nature, (B) the simultaneous inclusion of multiple tissues, and (C) altered responses to homeostatic signals, but (D) no direct feedback mechanisms for possible control or limitation. Priority of milk production is one important consequence of this homeorhetic regulation with possible constraints on other physiological functions. These general properties of the homeorhetic regulation of milk secretion are specifically characterized by a) milk production according milking (suckling) frequency, b) a natural but inadequate dry matter intake, c) the mobilization of fat acids + glycerol from adipose tissue and of amino acids from protein, d) the partitioning of metabolites, IgG, and dietary nutrients to the mammary gland, e) the stimulation of milk production by high protein intake, and f) a negligible negative energy balance (NEB) at low milk production. Such a combination assures the optimal milk yield for the nutrition of the calf and for its successful survival but without a metabolic challenge or health risk for the cow. However, selection for higher milk production (uncoupled from calf nutrition) and management have changed the above-listed properties, and the regulation of homeorhetic milk production of the modern high-producing dairy cow is nowadays mostly characterized by a) increasing and maximal milk production at increased milking frequency and, under certain circumstances, the uncoupling of the GH-IGF-1 axis, b) enduring insufficient dry matter intake in relation to requirement, c) the mobilization of energy (lipolysis) and release of non-esterified fatty acids (NEFA) above the acute requirement, d) the mobilization of amino acids, e) the partitioning of metabolites, IgG, and dietary nutrient to the mammary gland, f) the potential enhanced partitioning of energy to the mammary gland at high CP intake, g) a sudden and long-lasting NEB, and h) possibly lower weight gain or even net loss of energy during the entire lactation period. These altered and often unfavorable characteristics of high milk production are, furthermore, still regulated by homeorhesis and are thus also given top priority, lack feedback control, and possibly ensue at the expense of other functions without regard for health risks. Hence, the promotion of milk yield by breeding or management might cause metabolic overload, imbalances, or even antagonisms and makes possible health hazards evident. The high incidence of various diseases, the untimely culling rates, and the increasing number of dead cows during early lactation support the assumption of general health threats at high milk production. For this reason, more attention should be paid to the physiological mechanisms of homeorhetic-regulated milk production, its indisputable alterations by breeding and management, and the resulting health risks.
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Bogemova, Oksana y Elena Petrova. "Realization of the apology speech act: selection of speech tactics and the perlocutionary effect (based on the material of the Russian, English and French languages)". Litera, n.º 5 (mayo de 2021): 181–97. http://dx.doi.org/10.25136/2409-8698.2021.5.33004.
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This article examines the realization of the apology speech act in the three linguistic cultures: Russian, English, and French. The goal of this work is to determine the similarities and differences in functionality of the verbal act of apology in the context of the indicated cultures. The subject of this research is the expression with illocutionary meaning of apology. The authors review the composition of speech repertoire, means of realization of such speech act (conventional language, conventional speech, and nonconventional means), selection of speech tactics in expressing apology in form of the indirect speech act. Special attention is turned to perlocutionary effect, i.e. verbal response of the interlocutor to the addressed apology, as well as to the speech tactics that are frequent in the instances of expressing apology. The novelty of this work consists in studying the apology speech act of within the framework of cross-cultural pragmatics, with the use of practical material from the three linguistic cultures. The preliminary survey conducted among native speakers allowed concluding that the majority of respondents of these linguistic cultures attribute the ability to apologize with the image of a polite person. This particularly this pertains to the English-speaking and French-speaking cultures. Meanwhile, the examination of the articles of explanatory dictionaries demonstrates that the perception of the ability to apologize as a mandatory component of the concept of politeness is rather inherent to the mentality of native speakers, that to academic science. The analysis of practical material clarifies the speech repertoire and the frequency of selecting separate linguistic (imperative, performative) or speech means (speech cliché) used in realization of the direct speech act, as well as determines the key speech tactics used for expressing apology in form of the indirect speech act. Examination of the interlocutor’s verbal response as a perlocutionary effect on the apology indicates that this speech situation suggests a predominantly positive response. The maximal similarity in expressing apology is observed in the composition of speech repertoire of the speakers belonging to three different linguistic cultures, while the difference manifests namely in the selection of speech tactics for expressing apology or responding to it in form of the indirect speech act.
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Ruiz, Dante, Jorge Ortíz, Edgar Moreno, Claudio Fuerte, Vicente Venegas, Alejandro Vargas y Héctor Vergara. "Ferrites and Nanocrystalline Alloys Applied to DC–DC Converters for Renewable Energies". Applied Sciences 12, n.º 2 (12 de enero de 2022): 709. http://dx.doi.org/10.3390/app12020709.
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The medium frequency transformer (MFT) with nanocrystalline alloys is quintessential in new DC–DC converters involved in various front-end applications. The center piece to achieve high-performance, efficient MFTs is the core. There are various options of core materials; however, no deep information is available about which material characteristics and design procedure combo are best to get high performance MFTs while operating at maximal power density. To provide new insights about interrelation between the selection of the core material with the compliance technical specifications, differently to other proposals, this research work aims to design and build, with the same methodology, two MFT prototypes at 20 kHz, with nanocrystalline and ferrite cores, to highlight power density, and overall performance and cost, as matching design criteria. As the experimental results show, a nanocrystalline core has the highest power density (36.91 kW/L), designed at 0.8 T to obtain low losses at 20 kHz, achieving an efficiency of 99.7%. The power density in the ferrite MFT is 56.4% lower than in the nanocrystalline MFT. However, regarding construction cost, the ferrite MFT is 46% lower, providing this a trend towards low-cost DC–DC converters. Finally, high power density in MFTs increases the power density of power DC–DC converters, which have relevant applications in fuel cell-supplied systems, renewable energies, electric vehicles, and solid-state transformers.
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Frye, Mark A. "Treatment Guidelines for Acute Manic and Mixed Episodes of Bipolar Disorder". CNS Spectrums 14, S15 (diciembre de 2009): 8–11. http://dx.doi.org/10.1017/s1092852900004028.
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Bipolar disorder is a lifelong condition, and pharmacotherapy is essential to its long-term management. Once a comprehensive diagnostic assessment for acute or mixed mania has been completed, it is important to look at an evidence-based data set to guide treatment selection for mood stabilization.For most patients, lifetime adherence to pharmacotherapy is necessary for maximal mood stability. Pharmacotherapy is the primary treatment for bipolar disorder, as it has been found to be efficacious in treating acute episodes and preventing future episodes of bipolar I disorder. Combination therapy, including at least one mood stabilizer, may be necessary to treat acute depression and mania and to further prevent both depressive and manic recurrences. The goal is to minimize frequency, duration, and severity of depressive and manic symptoms with a treatment regimen, ideally a combination of pharmacotherapy and psychotherapy, that is positioned to maximize treatment adherence and minimize side effects.This discussion reviews some treatment guidelines for acute manic and mixed episodes associated with bipolar I disorder. Through the context of a case study, this discussion will attempt to provide an understanding and appreciation of Food and Drug Administration-approved and non-FDA-approved treatments for acute mania. In addition, the impact of alcohol as an example of drugs of abuse and its impact on the presentation of acute mania will be discussed.
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Guardabasso, Vincenzo, Alessandro D. Genazzani, Johannes D. Veldhuis y David Rodbard. "Objective assessment of concordance of secretory events in two endocrine time series". Acta Endocrinologica 124, n.º 2 (febrero de 1991): 208–18. http://dx.doi.org/10.1530/acta.0.1240208.
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Abstract. A new objective method is presented for investigating the presence of a temporal relationship between episodic release of two hormones. The two time series of hormone concentrations are first analysed by an objective method for peak detection. Both data series are then transformed into "quantized" or discretized series by recording the occurrence of a hormone pulse as an "event", characterized by the onset, the maximum, or another unique feature. The two quantized series are then matched, and the number of concordant events and discordant events are counted. Each point in series A is compared with a "time-window" of a selected number of points in series B, to accommodate small degree of mismatch between events in the two series. An index of concordance is computed, compensating for any spurious random coincidence: the "Specific Concordance", to evaluate the frequency of concordant events in excess of those expected on the basis of chance alone. This calculation is systematically repeated, interposing a range of time-lags between the two series. A graph of Specific Concordance versus time-lag indicates the time-lag corresponding to a maximal concordance. Simulations of random series of events are performed, and their degree of concordance is evaluated in a similar fashion, thus generating frequency distributions of Specific Concordance values under the null hypothesis of no temporal relationship. This permits the selection of criteria for statistical significance at any desired p-level, for one or many lag times, and for one or multiple subjects. Various degrees of concordance can also be simulated to evaluate the performance (sensitivity, statistical power) of this approach. These methods have been implemented as a collection of short microcomputer programmes, and applied to the study of the temporal relationship between β-endorphin and cortisol in normal subjects sampled every 10 min for 24 h. This analysis demonstrated concordance between events in the two series, with synchronous occurrence of β-endorphin and cortisol release events significantly more frequently than expected on the basis of random association (p<0.01).
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Price, J. Blair, Aaron E. Rusheen, Abhijeet S. Barath, Juan M. Rojas Cabrera, Hojin Shin, Su-Youne Chang, Christopher J. Kimble et al. "Clinical applications of neurochemical and electrophysiological measurements for closed-loop neurostimulation". Neurosurgical Focus 49, n.º 1 (julio de 2020): E6. http://dx.doi.org/10.3171/2020.4.focus20167.
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The development of closed-loop deep brain stimulation (DBS) systems represents a significant opportunity for innovation in the clinical application of neurostimulation therapies. Despite the highly dynamic nature of neurological diseases, open-loop DBS applications are incapable of modifying parameters in real time to react to fluctuations in disease states. Thus, current practice for the designation of stimulation parameters, such as duration, amplitude, and pulse frequency, is an algorithmic process. Ideal stimulation parameters are highly individualized and must reflect both the specific disease presentation and the unique pathophysiology presented by the individual. Stimulation parameters currently require a lengthy trial-and-error process to achieve the maximal therapeutic effect and can only be modified during clinical visits. The major impediment to the development of automated, adaptive closed-loop systems involves the selection of highly specific disease-related biomarkers to provide feedback for the stimulation platform. This review explores the disease relevance of neurochemical and electrophysiological biomarkers for the development of closed-loop neurostimulation technologies. Electrophysiological biomarkers, such as local field potentials, have been used to monitor disease states. Real-time measurement of neurochemical substances may be similarly useful for disease characterization. Thus, the introduction of measurable neurochemical analytes has significantly expanded biomarker options for feedback-sensitive neuromodulation systems. The potential use of biomarker monitoring to advance neurostimulation approaches for treatment of Parkinson’s disease, essential tremor, epilepsy, Tourette syndrome, obsessive-compulsive disorder, chronic pain, and depression is examined. Further, challenges and advances in the development of closed-loop neurostimulation technology are reviewed, as well as opportunities for next-generation closed-loop platforms.
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Hickey, Tony, Jules Devaux, Vijay Rajagopal, Amelia Power y David Crossman. "Paradoxes of Hymenoptera flight muscles, extreme machines". Biophysical Reviews 14, n.º 1 (febrero de 2022): 403–12. http://dx.doi.org/10.1007/s12551-022-00937-7.
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AbstractIn the Carboniferous, insects evolved flight. Intense selection drove for high performance and approximately 100 million years later, Hymenoptera (bees, wasps and ants) emerged. Some species had proportionately small wings, with apparently impossible aerodynamic challenges including a need for high frequency flight muscles (FMs), powered exclusively off aerobic pathways and resulting in extreme aerobic capacities. Modern insect FMs are the most refined and form large dense blocks that occupy 90% of the thorax. These can beat wings at 200 to 230 Hz, more than double that achieved by standard neuromuscular systems. To do so, rapid repolarisation was circumvented through evolution of asynchronous stimulation, stretch activation, elastic recoil and a paradoxically slow Ca2+ reuptake. While the latter conserves ATP, considerable ATP is demanded at the myofibrils. FMs have diminished sarcoplasmic volumes, and ATP is produced solely by mitochondria, which pack myocytes to maximal limits and have very dense cristae. Gaseous oxygen is supplied directly to mitochondria. While FMs appear to be optimised for function, several unusual paradoxes remain. FMs lack any significant equivalent to the creatine kinase shuttle, and myofibrils are twice as wide as those of within cardiomyocytes. The mitochondrial electron transport systems also release large amounts of reactive oxygen species (ROS) and respiratory complexes do not appear to be present at any exceptional level. Given that the loss of the creatine kinase shuttle and elevated ROS impairs heart function, we question how do FM shuttle adenylates at high rates and tolerate oxidative stress conditions that occur in diseased hearts?