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Zafar, Saima, Usman Ayub, Hend I. Alkhammash, and Nasim Ullah. "Framework for Efficient Auto-Scaling of Virtual Network Functions in a Cloud Environment." Sensors 22, no. 19 (October 7, 2022): 7597. http://dx.doi.org/10.3390/s22197597.
Повний текст джерелаАнотація:
Network Function Virtualization (NFV) offers an alternate method to design, deploy and manage network services. The NFV decouples network functions from the dedicated hardware and moves them to the virtual servers so that they can run in the software. One of the major strengths of the NFV is its ability to dynamically extend or reduce resources allocated to Virtual Network Functions (VNF) as needed and at run-time. There is a need for a comprehensive metering component in the cloud to store and process the metrics/samples for efficient auto-scaling or load-management of the VNF. In this paper, we propose an integrating framework for efficient auto-scaling of VNF using Gnocchi; a time-series database that is integrated within the framework to store, handle and index the time-series data. The objective of this study is to validate the efficacy of employing Gnocchi for auto-scaling of VNF, in terms of aggregated data points, database size, data recovery speed, and memory consumption. The employed methodology is to perform a detailed empirical analysis of the proposed framework by deploying a fully functional cloud to implement NFV architecture using several OpenStack components including Gnocchi. Our results show a significant improvement over the legacy Ceilometer configuration in terms of lower metering storage size, less memory utilization in processing and management of metrics, and reduced time delay in retrieving the monitoring data to evaluate alarms for the auto-scaling of VNF.
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Hu, Haiyan, Qiaoyan Kang, Shuo Zhao, Jianfeng Wang, and Youbin Fu. "Service Function Chain Deployment Method Based on Traffic Prediction and Adaptive Virtual Network Function Scaling." Electronics 11, no. 16 (August 22, 2022): 2625. http://dx.doi.org/10.3390/electronics11162625.
Повний текст джерелаАнотація:
With the development of network function virtualization (NFV), the resource management of service function chains (SFC) in the virtualized environment has gradually become a research hotspot. Usually, users hope that they can get the network services they want anytime and anywhere. The network service requests are dynamic and real-time, which requires that the SFC in the NFV environment can also meet the dynamically changing network service requests. In this regard, this paper proposes an SFC deployment method based on traffic prediction and adaptive virtual network function (VNF) scaling. Firstly, an improved network traffic prediction method is proposed to improve its prediction accuracy for dynamically changing network traffic. Secondly, the predicted traffic data is processed for the subsequent scaling of the VNF. Finally, an adaptive VNF scaling method is designed for the purpose of dynamic management of network virtual resources. The experimental results show that the method proposed in this paper can manage the network resources in dynamic scenarios. It can effectively improve the availability of network services, reduce the operating overhead and achieve a good optimization effect.
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Naidu, D. J. Samatha, and G. Hima Bindu. "INVESTIGATION ON ONLINE VNF SCALING IN A CLOUD DATACENTER USING ILP." International Journal of Computer Science and Mobile Computing 10, no. 8 (August 30, 2021): 32–35. http://dx.doi.org/10.47760/ijcsmc.2021.v10i08.005.
Повний текст джерелаАнотація:
NFV is the advanced technology in present situation. Online VNF Scaling in a cloud datacenter under multi-resource constraints were consider for formulating mathematical model. A new novel ILP Scaling algorithm works based on the regularization technique and dependent rounding.
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Yao, Yifu, Songtao Guo, Pan Li, Guiyan Liu, and Yue Zeng. "Forecasting assisted VNF scaling in NFV-enabled networks." Computer Networks 168 (February 2020): 107040. http://dx.doi.org/10.1016/j.comnet.2019.107040.
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Zeng, Zhihao, Zixiang Xia, Xiaoning Zhang, and Yexiao He. "SFC Design and VNF Placement Based on Traffic Volume Scaling and VNF Dependency in 5G Networks." Computer Modeling in Engineering & Sciences 134, no. 3 (2023): 1791–814. http://dx.doi.org/10.32604/cmes.2022.021648.
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Luo, Ziyue, and Chuan Wu. "An Online Algorithm for VNF Service Chain Scaling in Datacenters." IEEE/ACM Transactions on Networking 28, no. 3 (June 2020): 1061–73. http://dx.doi.org/10.1109/tnet.2020.2979263.
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Llorens-Carrodeguas, Alejandro, Irian Leyva-Pupo, Cristina Cervelló-Pastor, Luis Piñeiro, and Shuaib Siddiqui. "An SDN-Based Solution for Horizontal Auto-Scaling and Load Balancing of Transparent VNF Clusters." Sensors 21, no. 24 (December 11, 2021): 8283. http://dx.doi.org/10.3390/s21248283.
Повний текст джерелаАнотація:
This paper studies the problem of the dynamic scaling and load balancing of transparent virtualized network functions (VNFs). It analyzes different particularities of this problem, such as loop avoidance when performing scaling-out actions, and bidirectional flow affinity. To address this problem, a software-defined networking (SDN)-based solution is implemented consisting of two SDN controllers and two OpenFlow switches (OFSs). In this approach, the SDN controllers run the solution logic (i.e., monitoring, scaling, and load-balancing modules). According to the SDN controllers instructions, the OFSs are responsible for redirecting traffic to and from the VNF clusters (i.e., load-balancing strategy). Several experiments were conducted to validate the feasibility of this proposed solution on a real testbed. Through connectivity tests, not only could end-to-end (E2E) traffic be successfully achieved through the VNF cluster, but the bidirectional flow affinity strategy was also found to perform well because it could simultaneously create flow rules in both switches. Moreover, the selected CPU-based load-balancing method guaranteed an average imbalance below 10% while ensuring that new incoming traffic was redirected to the least loaded instance without requiring packet modification. Additionally, the designed monitoring function was able to detect failures in the set of active members in near real-time and active new instances in less than a minute. Likewise, the proposed auto-scaling module had a quick response to traffic changes. Our solution showed that the use of SDN controllers along with OFS provides great flexibility to implement different load-balancing, scaling, and monitoring strategies.
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Wu, Ziyan, Tianming Cui, Arvind Narayanan, Yang Zhang, Kangjie Lu, Antonia Zhai, and Zhi-Li Zhang. "GranularNF." ACM SIGMETRICS Performance Evaluation Review 50, no. 2 (August 30, 2022): 46–51. http://dx.doi.org/10.1145/3561074.3561092.
Повний текст джерелаАнотація:
In this paper, we consider the challenges that arise from the need to scale virtualized network functions (VNFs) at 100 Gbps line speed and beyond. Traditional VNF designs are monolithic in state management and scheduling: internally maintaining all states and operations associated with them. Without proper design considerations, it suffers from limitations when scaling at 100 Gbps link speed and beyond: the inability of efficient utilization of the cache because of the contention due to the frequent control plane activities, computational/memory-intensive tasks taking up CPU times, shares states causing the synchronization among the cores. We address these limitations by arguing for the need to granularly decompose a VNF into data/control components that are co-located within a server but can be independently scaled among the cores. To realize the approach, we design a "serverless" programming framework with novel abstraction to optimize the data components that must process packets at the line speed, reduce the contention of the data states and enable run-time scheduling of different components for improved resource utilization. The abstractions, combined with the runtime system that we design, help NFV developers focus on the logic and correctness of VNF programming without worrying about how VNFs may be scaled in or out. We evaluate our platform by comparing it with monolithic approaches using different workloads and by analyzing its advantages of separation on scalability, performance determinism, and feature velocity.
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Tang, Hong, Danny Zhou, and Duan Chen. "Dynamic Network Function Instance Scaling Based on Traffic Forecasting and VNF Placement in Operator Data Centers." IEEE Transactions on Parallel and Distributed Systems 30, no. 3 (March 1, 2019): 530–43. http://dx.doi.org/10.1109/tpds.2018.2867587.
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Xu, Ran. "Proactive VNF Scaling with Heterogeneous Cloud Resources: Fusing Long Short-Term Memory Prediction and Cooperative Allocation." Mathematical Problems in Engineering 2020 (January 28, 2020): 1–10. http://dx.doi.org/10.1155/2020/4371056.
Повний текст джерелаАнотація:
Network function virtualization (NFV) is designed to implement network functions by software that replaces proprietary hardware devices in traditional networks. In response to the growing demand of resource-intensive services, for NFV cloud service providers, software-oriented network functions face a number of challenges, such as dynamic deployment of virtual network functions and efficient allocation of multiple resources. This study aims at the dynamic allocation and adjustment of network multiresources and multitype flows for NFV. First, to seek a proactive approach to provision new instances for overloaded VNFs ahead of time, a model called long short-term memory recurrent neural network (LSTM RNN) is proposed to estimate flows in this paper. Then, based on the estimated flow, a cooperative and complementary resource allocation algorithm is designed to reduce resource fragmentation and improve the utilization. The final results demonstrate the advantage of the LSTM model on predicting the network function flow requirements, and our algorithm achieves good results and performance improvement in dynamically expanding network functions and improving resource utilization.
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Thomas, James S., Daniel M. Corcos, and Ziaul Hasan. "Kinematic and Kinetic Constraints on Arm, Trunk, and Leg Segments in Target-Reaching Movements." Journal of Neurophysiology 93, no. 1 (January 2005): 352–64. http://dx.doi.org/10.1152/jn.00582.2004.
Повний текст джерелаАнотація:
We studied target reaching tasks involving not only the arms but also the trunk and legs, which necessitated some trunk flexion. Such tasks can be successfully completed using an infinite number of combinations of segment motions due to the inherent kinematic redundancy with the excessive degrees of freedom (DOFs). Sagittal plane motions of six segments (shank, thigh, pelvis, trunk, humerus, and forearm) and dynamic torques of six joints (ankle, knee, hip, lumbar, shoulder, and elbow) were analyzed separately by principal component (PC) analyses to determine if there was a commonality among the shapes of the respective waveforms. Additionally, PC analyses were used to probe for constraining relationships among the 1) relative magnitudes of segment excursions and 2) the peak-to-peak dynamic joint torques. In summary, at the kinematic level, the tasks are simplified by the use of a single common waveform for all segment excursions with 89.9% variance accounted for (VAF), but with less fixed relationships among the relative scaling of the magnitude of segment excursions (62.2% VAF). However, at the kinetic level, the time course of the dynamic joint torques are not well captured by a single waveform (72.7% VAF), but the tasks are simplified by relatively fixed relationships among the scaling of dynamic joint torque magnitudes across task conditions (94.7% VAF). Taken together, these results indicate that, while the effective DOFs in a multi-joint task are reduced differently at the kinematic and kinetic levels, they both contribute to simplifying the neural control of these tasks.
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BARRY, MICHAEL E., GREGORY N. IVEY, KRAIG B. WINTERS, and JÖRG IMBERGER. "Measurements of diapycnal diffusivities in stratified fluids." Journal of Fluid Mechanics 442 (August 24, 2001): 267–91. http://dx.doi.org/10.1017/s0022112001005080.
Повний текст джерелаАнотація:
Linearly stratified salt solutions of different Prandtl number were subjected to turbulent stirring by a horizontally oscillating vertical grid in a closed laboratory system. The experimental set-up allowed the independent direct measurement of a root mean square turbulent lengthscale Lt, turbulent diffusivity for mass Kρ, rate of dissipation of turbulent kinetic energy ε, buoyancy frequency N and viscosity v, as time and volume averaged quantities. The behaviour of both Lt and Kρ was characterized over a wide range of the turbulence intensity measure, ε/vN2, and two regimes were identified.In the more energetic of these regimes (Regime E, where 300 < ε/vN2 < 105), Lt was found to be a function of v, κ and N, whilst Kρ was a function of v, κ and (ε/vN2)1/3. From these expressions for Lt and Kρ, a scaling relation for the root mean square turbulent velocity scale Ut was derived, and this relationship showed good agreement with direct measurements from other data sets.In the weaker turbulence regime (Regime W, where 10 < ε/vN2 < 300) Kρ was a function of v, κ and ε/vN2.For 10 < ε/vN2 < 1000, our directly measured diffusivities, Kρ, are approximately a factor of 2 different to the diffusivity predicted by the model of Osborn (1980). For ε/vN2 > 1000, our measured diffusivities diverge from the model prediction. For example, at ε/vN2 ≈ 104 there is at least an order of magnitude difference between the measured and predicted diffusivities.
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Johansson, Benny, and Svetlana Sukhotskya. "Drinking functional coherent mineral water accompanies a strengthening of the very low frequency impact on heart rate variability, and mono and multifractal heart rhythm dynamics in healthy humans." Functional Foods in Health and Disease 6, no. 6 (June 30, 2016): 388. http://dx.doi.org/10.31989/ffhd.v6i6.265.
Повний текст джерелаАнотація:
Background: Research on functional water has revealed its physiological functions and health-beneficial effects. Accordingly, this study explored the effects of drinking an average dietary volume of functional coherent mineral water (FCMW) on blood pressure, short-term cardiovascular variables, fractal heart rhythm dynamics, and salivary immunoglobulin A. Methods: Fifteen healthy subjects were randomized in a pre-post crossover design, selected the morning after an overnight fast. Short-term electrocardiography (ECG) was measured before and after drinking either control mineral water (CMW) or FCMW on two separate occasions. Saliva was collected for four minutes before the start of each ECG measurement. Blood pressure was monitored in five-minute intervals for one hour. Results: Drinking 100 ml of FCMW temporarily increased arterial blood pressure at 20 to 25 minutes in the 60 minutes post-drinking. Drinking CMW led to a significant reduction in the heart rate, while all-time domain and Power Spectral Density parameters (PSD) were unaffected. Consumption of FCMW resulted in a highly significant difference and decrease in heart rate, and an increase in NN interbeat intervals, and in two of the PSD parameters. A large increase in total power had a significant increasing effect on 2–3-minute oscillations of the very low frequency (VLF) power, indicating a specific change in the heartʼs intrinsic cardiac rhythm that is fundamental to health and well-being. An extension in mono and multifractal scaling of heart rate dynamics defines a healthy function and non-local adaptability, indicating a higher capacity to respond to unpredictable stimuli and stresses, a function which improves autonomic stability. The effect on the heart rate and VLF power suggest an efficient cellular metabolism and a stabilizing effect on mucosal immunoglobulin A. Conclusions: Functional coherent mineral water with an apparent non-local electromagnetic identity triggered in healthy subjects a sustainable sympathetic response in cardiac VLF power, which is considered an intrinsic health-promoting rhythm produced by the heart itself that accompanies adaptive mono and multifractal heart rhythm dynamics. Keywords: functional water, VLF-power, heart rate variability, fractal scaling, health improvement
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EFTAXIAS, K., P. FRANGOS, P. KAPIRIS, J. POLYGIANNAKIS, J. KOPANAS, A. PERATZAKIS, P. SKOUNTZOS, and D. JAGGARD. "REVIEW AND A MODEL OF PRE-SEISMIC ELECTROMAGNETIC EMISSIONS IN TERMS OF FRACTAL ELECTRODYNAMICS." Fractals 12, no. 02 (June 2004): 243–73. http://dx.doi.org/10.1142/s0218348x04002501.
Повний текст джерелаАнотація:
We introduce a new model of the generation of pre-seismic electromagnetic emissions, which explains the observed phenomenology in terms of its geometry and fractal electrodynamics. Accumulated evidence indicates that an earthquake can be viewed as a critical phenomenon culminating in a large event that corresponds to a type of critical point. The principle feature of criticality is the fractal organization in both space and time. Earthquakes display a complex spatio-temporal behavior: in addition to the regularity in the rate of occurrence (e.g. Gutenberg-Richter law, Omori law), the spatial distribution of epicenters is fractal and earthquakes occur on a fractal structure of faults. Thus, the hypothesis that the fault develops as a fractal is reasonable. A mounting body of laboratory evidence suggests that micro-fracturing of rocks are associated with the appearance of spontaneous charge production and transient electromagnetic emissions (EME). The emitting, diffusing and recombination charge accompanying the micro-fracturing, can act as current generated during the crack opening. In this view, an active crack or rupture, can be simulated by a "radiating element." The idea is that a fractal geo-antenna (FGA) can be formed as an array of line elements having a fractal distribution on the ground surface as the critical point is approached. We test this idea in terms of fractal electrodynamics: we argue that the precursory VLF-VHF EM signals associated with recent earthquakes in Greece are governed by characteristics (e.g. scaling laws, temporal evolution of the spectrum content, broad band spectrum region and accelerating emission rate) predicted by fractal electrodynamics.
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POPKOV, VLADISLAV, and MARIO SALERNO. "REDUCED DENSITY MATRIX AND ENTANGLEMENT ENTROPY OF PERMUTATIONALLY INVARIANT QUANTUM MANY-BODY SYSTEMS." International Journal of Modern Physics B 26, no. 27n28 (September 18, 2012): 1243009. http://dx.doi.org/10.1142/s0217979212430096.
Повний текст джерелаАнотація:
In this paper we discuss the properties of the reduced density matrix of quantum many body systems with permutational symmetry and present basic quantification of the entanglement in terms of the von Neumann (VNE), Renyi and Tsallis entropies. In particular, we show, on the specific example of the spin 1/2 Heisenberg model, how the RDM acquires a block diagonal form with respect to the quantum number k fixing the polarization in the subsystem conservation of Sz and with respect to the irreducible representations of the Sn group. Analytical expression for the RDM elements and for the RDM spectrum are derived for states of arbitrary permutational symmetry and for arbitrary polarizations. The temperature dependence and scaling of the VNE across a finite temperature phase transition is discussed and the RDM moments and the Rényi and Tsallis entropies calculated both for symmetric ground states of the Heisenberg chain and for maximally mixed states.
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Yonaiguchi, N., Y. Ida, M. Hayakawa, and S. Masuda. "A comparison of different fractal analyses for VHF electromagnetic emissions and their self-organization for the off-sea Miyagi-prefecture earthquake." Natural Hazards and Earth System Sciences 7, no. 4 (August 24, 2007): 485–93. http://dx.doi.org/10.5194/nhess-7-485-2007.
Повний текст джерелаАнотація:
Abstract. The VHF electromagnetic noise intensity data at several stations in the Tohoku area of Japan during the period of a rather large (with magnitude of 7.2) earthquake (Miyagi-ken oki earthquake) taken place on 16 August 2005, are analyzed by means of different fractal analysis methods, including (1) spectral slope estimation, (2) multi-fractal detrended fluctuation analysis and (3) multi-fractal wavelet transform modulus maxima method. It seems to the authors that there is no definite analysis method for the analysis of any seismogenic phenomenon, so that the only way we have to take, is to apply different methods to the same data for the detailed comparison of the results. This comparison enables us to deduce the properties commonly observed by the above methods. Because the most important feature common to these three methods, is that significant changes in fractal scaling characteristics are observed just during the earthquake (mainly before the earthquake) only at one station of Kunimi. Finally, we can come to the definite conclusion on the self-organization of VHF emissions only at one station in the present case.
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Li, Fengquan, Zhuling Sun, Mingyuan Liu, Shanfeng Yuan, Lei Wei, Chunfa Sun, Huimin Lyu, Kexin Zhu, and Guoying Tang. "A New Hybrid Algorithm to Image Lightning Channels Combining the Time Difference of Arrival Technique and Electromagnetic Time Reversal Technique." Remote Sensing 13, no. 22 (November 18, 2021): 4658. http://dx.doi.org/10.3390/rs13224658.
Повний текст джерелаАнотація:
Very-high-frequency (VHF) electromagnetic signals have been well used to image lightning channels with high temporal and spatial resolution due to their capability to penetrate clouds. A lightning broadband VHF interferometer with three VHF antennas configured in a scalene-triangle shape has been installed in Lhasa since 2019, to detect the lightning VHF signals. Using the signals from the VHF interferometer, a new hybrid algorithm, called the TDOA-EMTR technique, combining the time difference of arrival (TDOA) and the electromagnetic time reversal (EMTR) technique is introduced to image the two-dimensional lightning channels. The TDOA technique is firstly applied to calculate the initial solutions for the whole lightning flash. According to the results by the TDOA method, the domain used for the EMTR technique is predetermined, and then the EMTR technique is operated to obtain the final positioning result. Unlike the original EMTR technique, the low-power frequency points for each time window are removed based on the FFT spectrum. Metrics used to filter noise events are adjusted. Detailed imaging results of a negative cloud-to-ground (CG) lightning flash and an intra-cloud (IC) lightning flash by the TDOA method and the TDOA-EMTR are presented. Compared with the original EMTR method, the positioning efficiency can be improved by more than a factor of 3 to 4, depending on the scope of the pre-determined domain. Results show that the new algorithm can obtain much weaker radiation sources and simultaneously occurring sources, compared with the TDOA method.
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Brozzetti, Francesco, Alessandro Cesare Mondini, Cristina Pauselli, Paolo Mancinelli, Daniele Cirillo, Fausto Guzzetti, and Giusy Lavecchia. "Mainshock Anticipated by Intra-Sequence Ground Deformations: Insights from Multiscale Field and SAR Interferometric Measurements." Geosciences 10, no. 5 (May 15, 2020): 186. http://dx.doi.org/10.3390/geosciences10050186.
Повний текст джерелаАнотація:
The 2016 Central Italy seismic sequence was characterized by two main events: 24 August, Mw 6, and 30 October, Mw 6.5. We carried out high-resolution field sampling and DInSAR analysis of the coseismic and intra-sequence ground deformations along the Mt Vettore-Mt Bove causative fault (VBF). We found that during the intra-sequence period (24 August–30 October), the ground experienced some deformations whose final patterns seemed to be retraced and amplified by the following mainshock. We interpreted that (i) immediately after the 24 August earthquake, the deformation observed in the southern VBF expanded northwards and westwards over a Length of Deforming Ground (LDG) ranging between 28.7 and 36.3 km, and (ii) it extended to the whole portion of the hanging wall that was later affected by mainshock coseismic deformation. Assuming the LDG to be an indicator for an expected (=coseismic) surface rupture length and using known scaling functions, we obtained 6.4 ≤ Mw ≤ 6.7 for a possible incoming earthquake, which is consistent with the mainshock magnitude. We suggest that the evolution of the ground deformations after a significant seismic event might provide insights on the occurrence of new earthquakes with magnitudes comparable to or larger than the former.
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Bruning, Eric C., and Donald R. MacGorman. "Theory and Observations of Controls on Lightning Flash Size Spectra." Journal of the Atmospheric Sciences 70, no. 12 (November 22, 2013): 4012–29. http://dx.doi.org/10.1175/jas-d-12-0289.1.
Повний текст джерелаАнотація:
Abstract Previous analyses of very high frequency (VHF) Lightning Mapping Array (LMA) observations relative to the location of deep convective updrafts have noted a systematic pattern in flash characteristics. In and near strong updrafts, flashes tend to be smaller and more frequent, while flashes far from strong vertical drafts exhibit the opposite tendency. This study quantitatively tests these past anecdotal observations using LMA data for two supercell storms that occurred in Oklahoma in 2004. The data support a prediction from electrostatics that frequent breakdown and large flash extents are opposed. An energetic scaling that combines flash rate and flash area exhibits a power-law scaling regime on scales of a few kilometers and a maximum in flash energy at about 10 km. The spectral shape is surprisingly consistent across a range of moderate to large flash rates. The shape of this lightning flash energy spectrum is similar to that expected of turbulent kinetic energy spectra in thunderstorms. In line with the hypothesized role of convective motions as the generator of thunderstorm electrical energy, the correspondence between kinematic and electrical energy spectra suggests that advection of charge-bearing precipitation by the storm’s flow, including in turbulent eddies, couples the electrical and kinematic properties of a thunderstorm.
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Nguyen, Anh Tuan Le, Xuan Thanh Thi Le, Toan Thanh Thi Do, Cuong Tat Nguyen, Long Hoang Nguyen, Bach Xuan Tran, and Huong Thi Le. "Knowledge, Preference, and Willingness to Pay for Hepatitis B Vaccination Services among Woman of Reproductive Age in Vietnam." BioMed Research International 2019 (February 21, 2019): 1–7. http://dx.doi.org/10.1155/2019/9154918.
Повний текст джерелаАнотація:
Background. Hepatitis B virus (HBV) vaccine is a critical approach to prevent HBV transmission from mother to child. However, despite high HBV prevalence, evidence about the preference of women of productive age for HBV vaccine in Vietnam was constrained. This study aims to explore the preference and willingness to pay (WTP) for the HBV vaccine in Vietnamese women in productive age. Methods. A cross-sectional study was conducted in Hanoi in April 2016. A structured questionnaire was used to collect information about respondents’ socioeconomic status and knowledge about HBV vaccination. A contingent valuation approach was employed to measure the WTP for the HBV vaccine. Logistic and interval regressions were used to determine the associated factors. Results. Among 807 women, 80.8% were willing to have the vaccine injected which had the average price of 108,600 VND (95% CI, 97,580 VND–119,570 VND). Participants not suffering any diseases during pregnancy were more likely to be willing to pay for the HBV vaccine (OR = 3.41, 95% CI = 1.73–6.70). Not having the antenatal examination at central hospitals and working as farmers/workers were positively correlated with willingness to pay for this vaccine, while the number of children of respondents had a negative correlation with WTP. Conclusions. Our sampled women expressed a high willingness to pay for the vaccine. The price people were willing to pay for the vaccine, however, is equal to half of the actual price. These findings implied needs for better targeted public education interventions about HBV and the involvement of local medical staffs and the media in providing information. Efforts to reduce the price of the vaccine should also be warranted for scaling-up the coverage of this vaccine.
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Baumert, Mathias, Lars M. Brechtel, Juergen Lock, Andreas Voss, and Derek Abbott. "Scaling graphs of heart rate time series in athletes demonstrating the VLF, LF and HF regions." Physiological Measurement 27, no. 9 (July 14, 2006): N35—N39. http://dx.doi.org/10.1088/0967-3334/27/9/n01.
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Geiman, Joseph D., and James T. Kirby. "Unforced Oscillation of Rip-Current Vortex Cells." Journal of Physical Oceanography 43, no. 3 (March 1, 2013): 477–97. http://dx.doi.org/10.1175/jpo-d-11-0164.1.
Повний текст джерелаАнотація:
Abstract A numerical simulation of a monochromatic surface gravity wave–driven flow over an alongshore quasi-periodic rip-channeled beach using the wave-resolving model Funwave is used to investigate coherent, very low-frequency (VLF) motions with characteristic frequencies f < 4.0 mHz inside of the surf zone generated by wave breaking. These oscillations of the nearshore cellular vorticity pattern occur for shore-normal waves over a wide range of amplitudes of the incident wave field and occur despite the wave forcing being essentially constant. The oscillations occur at the lower end of the VLF spectrum or around fp = 0.55 mHz. For small incident wave amplitudes, an equilibrium state consisting of a staggered counterrotating vortex array generates a net weak alongshore current that is also seen in drifter trajectories observed in the field. Using a simpler pseudospectral vorticity model of a single dipole generated by a smooth, stationary in time forcing function sb, this study shows show that the Strouhal number of the vortex shedding process responsible for the oscillation is dependent on the circulation strength of the vortices in the dipole, as well as the bottom friction parameter. This process includes the pinching off, advection, and eventual regeneration of the vortex in the dipole. A simple scaling argument shows good agreement with the frequencies observed in the simulations.
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Zeng, Guoping, and Sha Tao. "A Generalized Linear Transformation and Its Effects on Logistic Regression." Mathematics 11, no. 2 (January 15, 2023): 467. http://dx.doi.org/10.3390/math11020467.
Повний текст джерелаАнотація:
Linear transformations such as min–max normalization and z-score standardization are commonly used in logistic regression for the purpose of scaling. However, the work in the literature on linear transformations in logistic regression has two major limitations. First, most work focuses on improving the fit of the regression model. Second, the effects of transformations are rarely discussed. In this paper, we first generalized a linear transformation for a single variable to multiple variables by matrix multiplication. We then studied various effects of a generalized linear transformation in logistic regression. We showed that an invertible generalized linear transformation has no effects on predictions, multicollinearity, pseudo-complete separation and complete separation. We also showed that multiple linear transformations do not have effects on the variance inflation factor (VIF). Numeric examples with a real data were presented to validate our results. Our results of no effects justify the rationality of linear transformations in logistic regression.
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Huston, Kyle J., Christina E. Rice, and Ronald G. Larson. "Forward Flux Sampling of Polymer Desorption Paths from a Solid Surface into Dilute Solution." Polymers 12, no. 10 (October 3, 2020): 2275. http://dx.doi.org/10.3390/polym12102275.
Повний текст джерелаАнотація:
We compute desorption rates for isolated polymers adsorbed to a solid wall with a rare event sampling technique called multilevel splitting, also known as forward flux sampling. We interpret computed rates with theories based on the conjecture that the product tdesDRg2 of the desorption time tdes and diffusivity D divided by squared radius of gyration Rg scales with exp(h/Rg) where h is the equilibrium ratio of adsorbed surface concentration of polymer Γ to bulk concentration of polymer c. As the polymer–wall interaction energy is increased, the slope of lntdesDRg2 vs. NVMFkBT nearly approaches unity, as expected for strongly-adsorbing chains, where N is the degree of polymerization and VMF is the height-averaged monomer–wall interaction energy for a strongly adsorbed chain. However, we also find that this scaling law is only accurate when adsorption strength per monomer exceeds a threshold value on the order of 0.3–0.5 kBT for a freely jointed chain without or with excluded volume effects. Below the critical value, we observe that tdesDRg2 becomes nearly constant with N, so that tdes∝Nα, with α≈2. This suggests a crossover from “strong” detachment-controlled to a “weak” diffusion-controlled desorption rate as VMF/kBT drops below some threshold. These results may partially explain experimental data, that in some cases show “strong” exponential dependence of desorption time on chain length, while in others a “weak” power-law dependence is found. However, in the “strong” adsorption case, our results suggest much longer desorption times than those measured, while the reverse is true in the weak adsorption limit. We discuss possible reasons for these discrepancies.
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Gu Jin-Hua, Ding Yan-Li, Yang Shi-E, Gao Xiao-Yong, Chen Yong-Sheng, and Lu Jing-Xiao. "A spectroscopic ellipsometry study of the abnormal scaling behavior of high-rate-deposited microcrystalline silicon films by VHF-PECVD technique." Acta Physica Sinica 58, no. 6 (2009): 4123. http://dx.doi.org/10.7498/aps.58.4123.
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Draz, Umar, Sana Yasin, Tariq Ali, Amjad Ali, Zaid Bin Faheem, Ning Zhang, Muhammad Hasan Jamal, and Dong-Young Suh. "ROBINA: Rotational Orbit-Based Inter-Node Adjustment for Acoustic Routing Path in the Internet of Underwater Things (IoUTs)." Sensors 21, no. 17 (September 6, 2021): 5968. http://dx.doi.org/10.3390/s21175968.
Повний текст джерелаАнотація:
The Internet of Underwater Things (IoUTs) enables various underwater objects be connected to accommodate a wide range of applications, such as oil and mineral exportations, disaster detection, and tracing tracking systems. As about 71% of our earth is covered by water and one-fourth of the population lives around this, the IoUT expects to play a vital role. It is imperative to pursue reliable communication in this vast domain, as human beings’ future depends on water activities and resources. Therefore, there is a urgent need for underwater communication to be reliable, end-to-end secure, and collision/void node-free, especially when the routing path is established between sender and sonobuoys. The foremost issue discussed in this area is its routing path, which has high security and bandwidth without simultaneous multiple reflections. Short communication range is also a problem (because of an absence of inter-node adjustment); the acoustic signals have short ranges and maximum-scaling factors that cause a delay in communication. Therefore, we proposed Rotational Orbit-Based Inter Node Adjustment (ROBINA) with variant Path-Adjustment (PA-ROBINA) and Path Loss (PL-ROBINA) for IoUTs to achive reliable communication between the sender and sonobuoys. Additionally, the mathematical-based path loss model was discussed to cover the PL-ROBINA strategy. Extensive simulations were conducted with various realistic parameters and the results were compared with state-of-the-art routing protocols. Extensive simulations proved that the proposed routing scheme outperformed different realistic parameters; for example, packet transmission 45% increased with an average end-to-end delay of only 0.3% respectively. Furthermore, the transmission loss and path loss (measured in dB) were 25 and 46 dB, respectively, compared with other algorithms, for example, EBER2 54%, WDFAD-BDR 54%, AEDG 49%, ASEGD 55%, AVH-AHH-VBF 54.5%, and TANVEER 39%, respectively. In addition, the individual parameters with ROBINA and TANVEER were also compared, in which ROBINA achieved a 98% packet transmission ratio compared with TANVEER, which was only 82%.
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Doubleday, Kevin, Daniel Gaile, Ravi Vijaya-Satya, Xianxian Liu, Kevin D'Auria, Soni Shukla, Han-Yu Chuang, Katie Quinn, and Darya Chudova. "Abstract 5015: Precision profile simulation study for a next generation sequencing bTMB assay." Cancer Research 82, no. 12_Supplement (June 15, 2022): 5015. http://dx.doi.org/10.1158/1538-7445.am2022-5015.
Повний текст джерелаАнотація:
Abstract Background: Precision profile simulations (PPS) can be used to assess variability of biomarker profiles and provide valuable insight into assay performance, especially when reliable precision estimates can not be obtained empirically due to scarcity of representative samples or insufficient materials per sample. A PPS was conducted for the GuardantOMNI assay to characterize the expected variability in blood tumor mutational burden (bTMB) score across a representative range of expected bTMB scores in clinical samples. The simulations were aligned to, but not completely prescribed by, the PPS guidance provided in Guidance for Industry and and Food and Drug Administration Staff Class II Special Controls Guidance Document: Ovarian Adnexal Mass Assessment Score Test System. A sample’s bTMB score is a real valued quantity (e.g., bTMB = 21.04 mut/Mb) that is derived by multiplying the number of qualified mutations observed within a targeted panel by a scaling factor. Variability in observed bTMB scores for a given blood sample is governed primarily by sample coverage, tumor shedding level, and the assay somatic variant detection probabilities (a function of underlying variant allele frequencies, VAFs). Methods: The relationship between site-specific total molecule counts and coverage was modeled utilizing a composite dataset consisting of both clinical and contrived samples. Sample coverage was modeled using variance component estimates from Precision Study data (18 cancer samples each with 6 to 18 replicates). The reference, single-strand mutant, and double-strand mutant molecule counts for a somatic variant site detected in at least one sample replicate were modeled utilizing a bias corrected Dirichlet Multinomial model. The variants with the simulated VAF and coverage levels were processed with the GuardantOMNI germline/somatic classifier to account for the uncertainty in germline/somatic classification at lower coverage values. Results: Precision profiles consisting of simulation derived %CV estimates for 18 clinical samples with a representative set of mean bTMB scores were generated. The PPS bTMB score distributions were consistent with the bTMB scores observed in the Precision Study, supported by visualization and confidence intervals at level 0.05 margins of equivalence for the empirical mean bTMB and standard deviation estimates. The sample specific %CV estimates were observed, in most instances, to decrease with increasing input levels for matched targeted LoD (Limit of Detection) simulation results. Precision profile %CV estimates were observed to be inversely related to mean bTMB scores. Conclusions: The results provide proof of principle that estimation of GuardantOMNI bTMB score precision via an intuitive and interpretable simulation model is viable. The simulation results were consistent with empirical data and general expectations regarding the precision of the bTMB scores. Citation Format: Kevin Doubleday, Daniel Gaile, Ravi Vijaya-Satya, Xianxian Liu, Kevin D'Auria, Soni Shukla, Han-Yu Chuang, Katie Quinn, Darya Chudova. Precision profile simulation study for a next generation sequencing bTMB assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5015.
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"Traffic Forecast Assisted Adaptive VNF Dynamic Scaling." KSII Transactions on Internet and Information Systems 16, no. 11 (November 30, 2022). http://dx.doi.org/10.3837/tiis.2022.11.007.
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"Dynamic 5G Network Slicing." International Journal of Advanced Trends in Computer Science and Engineering 10, no. 2 (April 5, 2021): 1006–10. http://dx.doi.org/10.30534/ijatcse/2021/741022021.
Повний текст джерелаАнотація:
5G network slicing is the use of network virtualization to divide single network connections into multiple distinct virtual connections that provide different amounts of resources to different types of traffic. A 5G NS (Network Slicing) instance is composed of a set of virtual network function (VNF) instances to form the end-to-end (E2E) virtual network for the slice to operate independently. The deployment of a NS is a typical virtual network embedding (VNE) problem. The proposed algorithm consists of three parts. First, we devise a Holt-Winters (HW) prediction algorithm to determine traffic demand for network slices. This method is intended to avoid frequent changes in network topology. Second, we propose a virtual network function (VNF) adaptive scaling strategy to reasonably determine the number of VNFs and resources required for network slices to avoid resource wastage. Finally, we develop a proactive online algorithm to deploy network slices.
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Xia, Rui, Haipeng Dai, Jiaqi Zheng, Rong Gu, Xiaoyu Wang, Weijun Wang, and Guihai Chen. "SAFE: Service Availability via Failure Elimination Through VNF Scaling." IEEE/ACM Transactions on Networking, 2023, 1–16. http://dx.doi.org/10.1109/tnet.2022.3233488.
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Qu, Kaige, Weihua Zhuang, Xuemin Shen, Xu Li, and Jaya Rao. "Dynamic Resource Scaling for VNF over Nonstationary Traffic: A Learning Approach." IEEE Transactions on Cognitive Communications and Networking, 2020, 1. http://dx.doi.org/10.1109/tccn.2020.3018157.
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Seo, Namjin, DongNyeong Heo, and Heeyoul Choi. "Graph Neural Networks with Reinforcement Learning for Advanced VNF Scaling in Network Management." SSRN Electronic Journal, 2023. http://dx.doi.org/10.2139/ssrn.4353607.
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Klemash, Mary E. Galanko, Sarah S. Bedair, Tobias M. Kiebala, Daniel A. Diamond, Ryan Q. Rudy, and Victor Farm-Guoo Tseng. "Frequency Scaling of Passive Voltage Gain in 1-Port VHF Quartz Resonators." Journal of Microelectromechanical Systems, 2022, 1–10. http://dx.doi.org/10.1109/jmems.2022.3155953.
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Demol, Miro, Kim Calders, Hans Verbeeck, and Bert Gielen. "Forest aboveground volume assessments with terrestrial laser scanning: a ground-truth validation experiment in temperate, managed forests." Annals of Botany, September 2, 2021. http://dx.doi.org/10.1093/aob/mcab110.
Повний текст джерелаАнотація:
Abstract Background and Aims Quantifying the Earth’s forest aboveground biomass (AGB) is indispensable for effective climate action and developing forest policy. Yet, current allometric scaling models (ASM) to estimate AGB suffer several drawbacks related to model selection and calibration data traceability uncertainties. Terrestrial laser scanning (TLS) offers a promising non-destructive alternative. Tree volume is reconstructed from TLS point clouds with Quantitative Structure Models (QSM) and converted to AGB with wood basic density. Earlier studies have found overall TLS-derived forest volume estimates to be accurate, but highlighted problems for reconstructing finer branches. Our objective was to evaluate TLS for estimating tree volumes by comparison with reference volumes and volumes from ASMs. Methods We quantified the woody volume of 65 trees in Belgium (77 – 2.800 L; Pinus sylvestris, Fagus sylvatica, Larix decidua, Fraxinus excelsior) with QSMs and destructive reference measurements. We tested a volume expansion factor (VEF) approach by multiplying the solid and merchantable volume from QSM with literature VEF values. Key Results Stem volume was reliably estimated with TLS. Total volume was overestimated by +21% using original QSMs, by +9% and -12% using two sets of VEF-augmented QSMs, and by -7.3% using best-available allometric models. The most accurate method differed per site, and the prediction errors for each method varied considerably between sites. Conclusions VEF-augmented QSMs were only slightly better than original QSMs for estimating tree volume for common species in temperate forests. Despite satisfying estimates with ASMs, the model choice was a large source of uncertainty, and species-specific models did not always exist. Therefore, we advocate for further improving tree volume reconstructions with QSMs, especially for fine branches, instead of collecting more ground-truth data to calibrate VEF and allometric models. Promising developments such as improved coregistration and smarter filtering approaches are ongoing to further constrain volumetric errors in TLS-derived estimates.
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Nash, Christopher J., and David J. Cole. "Measurement and Modeling of the Effect of Sensory Conflicts on Driver Steering Control." Journal of Dynamic Systems, Measurement, and Control 141, no. 6 (March 13, 2019). http://dx.doi.org/10.1115/1.4042876.
Повний текст джерелаАнотація:
In previous work, a new model of driver steering control incorporating sensory dynamics was derived and used to explain the performance of drivers in a simulator with full-scale motion feedback. This paper describes further experiments investigating how drivers steer with conflicts between their visual and vestibular measurements, caused by scaling or filtering the physical motion of the simulator relative to the virtual environment. The predictions of several variations of the new driver model are compared with the measurements to understand how drivers perceive sensory conflicts. Drivers are found to adapt well in general, unless the conflict is large, in which case they ignore the physical motion and rely on visual measurements. Drivers make greater use of physical motion which they rate as being more helpful, achieving a better tracking performance. Sensory measurement noise is shown to be signal-dependent, allowing a single set of parameters to be found to fit the results of all the trials. The model fits measured linear steering behavior with an average “variance accounted for (VAF)” of 86%.
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Azimzade, Youness. "Invasion front dynamics of interactive populations in environments with barriers." Scientific Reports 12, no. 1 (January 17, 2022). http://dx.doi.org/10.1038/s41598-022-04806-x.
Повний текст джерелаАнотація:
AbstractInvading populations normally comprise different subpopulations that interact while trying to overcome existing barriers against their way to occupy new areas. However, the majority of studies so far only consider single or multiple population invasion into areas where there is no resistance against the invasion. Here, we developed a model to study how cooperative/competitive populations invade in the presence of a physical barrier that should be degraded during the invasion. For one dimensional (1D) environment, we found that a Langevin equation as $$dX/dt=V_ft+\sqrt{D_f}\eta (t)$$ d X / d t = V f t + D f η ( t ) describing invasion front position. We then obtained how $$V_f$$ V f and $$D_f$$ D f depend on population interactions and environmental barrier intensity. In two dimensional (2D) environment, for the average interface position movements we found a Langevin equation as $$dH/dt=V_Ht+\sqrt{D_H}\eta (t)$$ d H / d t = V H t + D H η ( t ) . Similar to the 1D case, we calculate how $$V_H$$ V H and $$D_H$$ D H respond to population interaction and environmental barrier intensity. Finally, the study of invasion front morphology through dynamic scaling analysis showed that growth exponent, $$\beta$$ β , depends on both population interaction and environmental barrier intensity. Saturated interface width, $$W_{sat}$$ W sat , versus width of the 2D environment (L) also exhibits scaling behavior. Our findings show revealed that competition among subpopulations leads to more rough invasion fronts. Considering the wide range of shreds of evidence for clonal diversity in cancer cell populations, our findings suggest that interactions between such diverse populations can potentially participate in the irregularities of tumor border.
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Hayano, Junichiro, Norihiro Ueda, Masaya Kisohara, Emi Yuda, Robert M. Carney, and James A. Blumenthal. "Survival Predictors of Heart Rate Variability After Myocardial Infarction With and Without Low Left Ventricular Ejection Fraction." Frontiers in Neuroscience 15 (January 28, 2021). http://dx.doi.org/10.3389/fnins.2021.610955.
Повний текст джерелаАнотація:
BackgroundHeart rate variability (HRV) and heart rate (HR) dynamics are used to predict the survival probability of patients after acute myocardial infarction (AMI), but the association has been established in patients with mixed levels of left ventricular ejection fraction (LVEF).ObjectiveWe investigated whether the survival predictors of HRV and HR dynamics depend on LVEF after AMI.MethodsWe studied 687 post-AMI patients including 147 with LVEF ≤35% and 540 with LVEF >35%, of which 23 (16%) and 22 (4%) died during the 25 month follow-up period, respectively. None had an implanted cardioverter-defibrillator. From baseline 24 h ECG, the standard deviation (SDNN), root mean square of successive difference (rMSSD), percentage of successive difference >50 ms (pNN50) of normal-to-normal R-R interval, ultra-low (ULF), very-low (VLF), low (LF), and high (HF) frequency power, deceleration capacity (DC), short-term scaling exponent (α1), non-Gaussianity index (λ25s), and the amplitude of cyclic variation of HR (Acv) were calculated.ResultsThe predictors were categorized into three clusters; DC, SDNN, α1, ULF, VLF, LF, and Acv as Cluster 1, λ25s independently as Cluster 2, and rMSSD, pNN50, and HF as Cluster 3. In univariate analyses, mortality was best predicted by indices belonging to Cluster 1 regardless of LVEF. In multivariate analyses, however, mortality in patients with low LVEF was best predicted by the combinations of Cluster 1 predictors or Cluster 1 and 3 predictors, whereas in patients without low LVEF, it was best predicted by the combinations of Cluster 1 and 2 predictors.ConclusionThe mortality risk in post-AMI patients with low LVEF is predicted by indices reflecting decreased HRV or HR responsiveness and cardiac parasympathetic dysfunction, whereas in patients without low LVEF, the risk is predicted by a combination of indices that reflect decreased HRV or HR responsiveness and indicator that reflects abrupt large HR changes suggesting sympathetic involvement.
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Чернов, Ю. К., А. Ю. Чернов, and М. И. Читишвили. "Models of strong ground motions for probabilistic detailed seismic zoning of the territory of North Ossetia-Alania. Part 2." Геология и геофизика Юга России, no. 3 (September 20, 2019). http://dx.doi.org/10.23671/vnc.2019.3.36753.
Повний текст джерелаАнотація:
В статье описываются модели спектров и акселерограмм колебаний грунта, а также ytfhfrnthys ( спектральных ) моделей балльности сотрясений, разработанные в рамках исследований по созданию нового варианта вероятностной карты ДСР территории РСОАлания. Спектры Фурье и спектры реакции моделируются в виде наборов уровней спектральной плотности (S) и спектральных ускорений (SA) на различных частотах (f). Эти параметры рассматриваются как случайные величины, имеющие лог. нормальное распределение вероятностей при различных сочетаниях магнитуд землетрясений (М) и расстояний до очага (D). Построение функций распределения выполнено в два этапа. Сначала определены среднестатистические оценки S(М,D,f) или SA(М,D,f), а затем путем корректировок эти оценки приближены к условиям рассматриваемой территории. Корректировки сделаны на основе анализа сейсмогеологических особенностей района, влияющих на рассматриваемые параметры СДГ. Базовые ( среднестатистические ) построения проведены с использованием более 2500 спектров ускорений колебаний грунта при землетрясениях различных районов мира с М2,5 7,7, D2 808 км и I3 10 баллов MSK. Применен также новый метод восстановления спектров колебаний грунта при землетрясениях по их макросейсмическому полю. Для этого использованы данные макросейсмических обследований 27 сильных землетрясений региона с M3,5 7,0 и силой сотрясений в эпицентре 6 9 баллов MSK. Привлечены также данные о силе сотрясений в эпицентрах 189 ощутимых и сильных землетрясений данного района из работы А.А. Никонова. Спектральные балльности (Iс) рассчитываются через спектры Фурье по зависимостям из работы Ю.К. Чернова и А.Ю. Чернова (2008 г.). Акселерограммы моделировались как в виде временных функций, генерируемых методом случайных колебаний, так и подбором записей реальных землетрясений с последующим их масштабированием в спектральновременной области. В обоих случаях критериями точности построений являлись близости спектров, а также амплитуд, периодов и длительностей, измеренных на акселерограммах к соответствующим моделям спектров и описанным в первой части статьи моделям единичных параметров. Получаемые посредством разработанных моделей оценки всех параметров СДГ сопоставлялись между собой, а также с оценками по другим известным в мире моделям тесты на внутреннюю и внешнюю согласованность. Показан высокий уровень согласованности и непротиворечивости всех моделируемых параметров СДГ при землетрясениях всех рассматриваемых M и D. Выполненные для сравнения такие же тесты для некоторых других моделей СДГ, рекомендуемых для использования на территории РФ, показали преимущества наших моделей по данному показателю. Разработанные модели СДГ могут быть полезными при вероятностном и детерминистском ( ситуационном ) анализе сейсмической опасности территории РСОАлания и других районов со сходными сейсмогеологическими условиями. The article describes the models of spectra and accelerograms of soil vibrations, as well as nontraditional (spectral) models of shake intensity, developed as part of investigation to create a new version of the DSZ probability map of the territory of North OssetiaAlania. Fourier spectra and reaction spectra are modeled as sets of spectral density levels (S) and spectral accelerations (SA) at different frequencies (f). These parameters are considered as random variables having a log. normal probability distribution for various combinations of earthquake magnitudes (M) and focal distance (D). The construction of distribution functions is performed in two stages. First, average estimates are defined S(М,D,f) or SA(М,D,f), and then, by adjustments, these estimates are approximated to the conditions of the considered territory. Corrections are made on the basis of the analysis of seismic and geological features of the region, affecting the considered parameters of SGM. Basic (average) constructions were carried out using more than 2500 spectra of soil vibration accelerations during earthquakes in various regions of the world with M2.5 7.7, D2 808 km and I3 10 MSK points. A new method has also been applied for reconstructing the spectra of soil vibrations during earthquakes according to their macroseismic field. For this the data from macroseismic surveys of 27 strong earthquakes in the region with M3.5 7.0 and shaking strength at the epicenter of 6 9 MSK points was used. The data on the strength of the shaking at the epicenters of 189 tangible and strong earthquakes in this region from the work of A.A. Nikonov was used. The spectral intensities (Iс) are calculated through the Fourier spectra according to the dependences from the work of Yu.K. Chernova and A.Yu. Chernova (2008). Accelerograms were modeled both in the form of time vibrations generated by the random vibrations method and by selecting records of real earthquakes with their subsequent scaling in the spectraltemporal area. In both cases, the criteria for the accuracy of the constructions were the proximity of the spectra, as well as the amplitudes, periods, and durations measured on the accelerograms to the corresponding spectral models and models of unit parameters described in the first part of the article. Estimates obtained by means of the developed models for evaluating all the parameters of the SGM were compared with each other, as well as with estimates using other models known in the world tests for internal and external consistency. A high level of consistency and noncontradiction of all simulated SGM parameters during earthquakes of all considered M and D is shown. The same tests performed for comparison for some other SGM models recommended for use in the Russian Federation showed the advantages of our models according to this indicator. The developed SGM models can be useful for probabilistic and deterministic (situational) analysis of seismic hazard in the territory of North OssetiaAlania and other regions with similar seismic and geological conditions
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Yang, Letian, Yuliang Zhao, Baiyu Qiao, Yating Wang, Ling Zhang, Tianlei Cui, and Ping Fu. "Heart Rate Variability and Prognosis in Hemodialysis Patients: A Meta-Analysis." Blood Purification, December 8, 2020, 1–11. http://dx.doi.org/10.1159/000511723.
Повний текст джерелаАнотація:
<b><i>Background:</i></b> Heart rate variability (HRV) means the variation in time of beat-to-beat interval. Lower HRV has been shown to be related with death and cardiovascular events in previous studies. In the last few years, the number of patients with ESRD has increased steadily. Maintenance hemodialysis is the most prevalent renal replacement therapy in patients with ESRD. This study aims to investigate if decreased HRV is an independent predictor of mortality in maintenance hemodialysis patients. <b><i>Methods:</i></b> Pubmed/Medline, EMBASE, Ovid, the Web of Science, and the Cochrane Central Register of Controlled Trials databases were searched up to October 1, 2019, for full-text articles in English. Cohort studies reporting the association between HRV and prognosis in hemodialysis patients were selected. Data extraction was performed by 2 reviewers independently, with adjudication by a third reviewer. Extracted data included the study characteristics, HRV measurement and research outcomes. Hazard ratios (HRs) and 95% confidence interval (CI) were pooled in a random-effects model for outcomes of all-cause and cardiovascular mortality. Heterogeneity assessment, subgroup analyses, and sensitivity analysis were conducted. <b><i>Results:</i></b> A total of 7 studies were eligible. HRV metrics consist of SDNN, SDANN, RMSSD, pNN50, HRVTI, ULF, VLF, LF, HF, LF/HF ratio, HRT, DC, and scaling exponents α1 and α2. Decreased HRV was associated with higher all-cause mortality (HR: 1.63, 95% CI: 1.11–2.39, <i>p</i> = 0.014) and cardiovascular mortality (HR: 1.07, 95% CI: 1.00–1.15, <i>p</i> = 0.045). Among the different HRV metrics, decreased SDANN (<i>p</i> < 0.001) and decreased LF/HF ratio (<i>p</i> = 0.001) were identified as predictors of all-cause death. Decreased SDNN, SDANN, and LF/HF ratio were identified as predictors of cardiovascular death (<i>p</i> = 0.004, <i>p</i> = 0.001, and <i>p</i> = 0.002). <b><i>Conclusions:</i></b> Decreased HRV is associated with higher risk of all-cause and cardiovascular death in the hemodialysis population. Decreased SDANN and LF/HF were identified as predictors of both all-cause and cardiovascular mortality, while the utility of other HRV metrics requires further investigation. The protocol for this study was registered with PROSPERO (CRD42019141886).