Journal articles on the topic 'Two Wave Missing Data'
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Rioux, Charlie, Antoine Lewin, Omolola A. Odejimi, and Todd D. Little. "Reflection on modern methods: planned missing data designs for epidemiological research." International Journal of Epidemiology 49, no. 5 (May 1, 2020): 1702–11. http://dx.doi.org/10.1093/ije/dyaa042.
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Abstract Taking advantage of the ability of modern missing data treatments in epidemiological research (e.g. multiple imputation) to recover power while avoiding bias in the presence of data that is missing completely at random, planned missing data designs allow researchers to deliberately incorporate missing data into a research design. A planned missing data design may be done by randomly assigning participants to have missing items in a questionnaire (multiform design) or missing occasions of measurement in a longitudinal study (wave-missing design), or by administering an expensive gold-standard measure to a random subset of participants while the whole sample is administered a cheaper measure (two-method design). Although not common in epidemiology, these designs have been recommended for decades by methodologists for their benefits—notably that data collection costs are minimized and participant burden is reduced, which can increase validity. This paper describes the multiform, wave-missing and two-method designs, including their benefits, their impact on bias and power, and other factors that must be taken into consideration when implementing them in an epidemiological study design.
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Cavaleri, Luigi. "Wave Modeling—Missing the Peaks." Journal of Physical Oceanography 39, no. 11 (November 1, 2009): 2757–78. http://dx.doi.org/10.1175/2009jpo4067.1.
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Abstract The paper analyzes the capability of the present wave models of properly reproducing the conditions during and at the peak of severe and extreme storms. After providing evidence that this is often not the case, the reasons for it are explored. First, the physics of waves considered in wave models is analyzed. Although much improved with respect to the past, the wind accuracy is still a relevant factor at the peak of the storms. Other factors such as wind variability and air density are considered. The classical theory of wave generation by J. W. Miles’s mechanism, with subsequent modifications, is deemed not sufficiently representative of extreme conditions. The presently used formulations for nonlinear energy transfer are found to lead to too wide distributions in frequency and direction, hence reducing the input by wind. Notwithstanding some recent improvements, the white-capping formulation still depends on parameters fitted to the bulk of the data. Hence, it is not obvious how they will perform in extreme conditions when the physics is likely to be different. Albeit at different levels in different models, the advection still implies the spreading of energy, hence a spatial smoothing of the peaks. The lack of proper knowledge of the ocean currents is found to substantially affect the identification of how much energy can—in some cases—be concentrated at a given time and location. The implementation of the available theories and know-how in the present wave models are often found inconsistent from model to model. It follows that in this case, it is not possible to exchange corresponding pieces of software between two models without substantially affecting the quality of the results. After analyzing various aspects of a wave model, the paper makes some general considerations. Because wave growth is the difference between processes (input and output) involving large amounts of energy, it is very sensitive to small modifications of one or more processes. Together with the strong, but effective, tuning present in a wave model, this makes the introduction of new physics more complicated. It is suggested that for long-term improvements, operational and experimental applications need to proceed along parallel routes, with the latter looking more to the physics without the necessity of an immediately improved overall performance. In view of the forthcoming increase of computer power, a sensitivity study is suggested to identify the most critical areas in a wave model to determine where to invest for further improvements. The limits on the description of the physics of the processes when using the spectral approach, particularly in extreme conditions, are considered. For further insights and as a way to validate the present theories in these conditions, the use is suggested of numerical experiments simulating in great detail the physical interaction between the lower atmosphere and the single waves.
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Rhemtulla, Mijke, Fan Jia, Wei Wu, and Todd D. Little. "Planned missing designs to optimize the efficiency of latent growth parameter estimates." International Journal of Behavioral Development 38, no. 5 (January 23, 2014): 423–34. http://dx.doi.org/10.1177/0165025413514324.
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We examine the performance of planned missing (PM) designs for correlated latent growth curve models. Using simulated data from a model where latent growth curves are fitted to two constructs over five time points, we apply three kinds of planned missingness. The first is item-level planned missingness using a three-form design at each wave such that 25% of data are missing. The second is wave-level planned missingness such that each participant is missing up to two waves of data. The third combines both forms of missingness. We find that three-form missingness results in high convergence rates, little parameter estimate or standard error bias, and high efficiency relative to the complete data design for almost all parameter types. In contrast, wave missingness and the combined design result in dramatically lowered efficiency for parameters measuring individual variability in rates of change (e.g., latent slope variances and covariances), and bias in both estimates and standard errors for these same parameters. We conclude that wave missingness should not be used except with large effect sizes and very large samples.
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Lu, Peiyi, and Mack Shelley. "Testing the Missing Mechanism of Demographic and Health Variables in the Health and Retirement Study." Innovation in Aging 4, Supplement_1 (December 1, 2020): 509. http://dx.doi.org/10.1093/geroni/igaa057.1644.
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Abstract Studies using data from longitudinal health survey of older adults usually assumed the data were missing completely at random (MCAR) or missing at random (MAR). Thus subsequent analyses used multiple imputation or likelihood-based method to handle missing data. However, little existing research actually examines whether the data met the MCAR/MAR assumptions before performing data analyses. This study first summarized the commonly used statistical methods to test missing mechanism and discussed their application conditions. Then using two-wave longitudinal data from the Health and Retirement Study (HRS; wave 2014-2015 and wave 2016-2017; N=18,747), this study applied different approaches to test the missing mechanism of several demographic and health variables. These approaches included Little’s test, logistic regression method, nonparametric tests, false discovery rate, and others. Results indicated the data did not meet the MCAR assumption even though they had a very low rate of missing values. Demographic variables provided good auxiliary information for health variables. Health measures (e.g., self-reported health, activity of daily life, depressive symptoms) met the MAR assumptions. Older respondents could drop out and die in the longitudinal survey, but attrition did not significantly affect the MAR assumption. Our findings supported the MAR assumptions for the demographic and health variables in HRS, and therefore provided statistical justification to HRS researchers about using imputation or likelihood-based methods to deal with missing data. However, researchers are strongly encouraged to test the missing mechanism of the specific variables/data they choose when using a new dataset.
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Frasier, C., and D. Winterstein. "Analysis of conventional and converted mode reflections at Putah sink, California using three‐component data." GEOPHYSICS 55, no. 6 (June 1990): 646–59. http://dx.doi.org/10.1190/1.1442877.
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In 1980 Chevron recorded a three‐component seismic line using vertical (V) and transverse (T) motion vibrators over the Putah sink gas field near Davis, California. The purpose was to record the total vector motion of the various reflection types excited by the two sources, with emphasis on converted P‐S reflections. Analysis of the conventional reflection data agreed with results from the Conoco Shear Wave Group Shoot of 1977–1978. For example, the P‐P wave section had gas‐sand bright spots which were absent in the S‐S wave section. Shot profiles from the V vibrators showed strong P‐S converted wave events on the horizontal radial component (R) as expected. To our surprise, shot records from the T vibrators showed S‐P converted wave events on the V component, with low amplitudes but high signal‐to‐noise (S/N) ratios. These S‐P events were likely products of split S‐waves generated in anisotropic subsurface media. Components of these downgoing waves in the plane of incidence were converted to P‐waves on reflection and arrived at receivers in a low‐noise time window ahead of the S‐S waves. The two types of converted waves (P‐S and S‐P) were first stacked by common midpoint (CMP). The unexpected S‐P section was lower in true amplitude but much higher in S/N ratio than the P‐S section. The Winters gas‐sand bright spot was missing on the converted wave sections, mimicking the S‐S reflectivity as expected. CRP gathers were formed by rebinning data by a simple ray‐tracing formula based on the asymmetry of raypaths. CRP stacking improved P‐S and S‐P event resolution relative to CMP stacking and laterally aligned structural features with their counterparts on P and S sections. Thus, the unexpected S‐P data provided us with an extra check for our converted wave data processing.
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Rebernik, Teja, Jidde Jacobi, Mark Tiede, and Martijn Wieling. "Accuracy Assessment of Two Electromagnetic Articulographs: Northern Digital Inc. WAVE and Northern Digital Inc. VOX." Journal of Speech, Language, and Hearing Research 64, no. 7 (July 16, 2021): 2637–67. http://dx.doi.org/10.1044/2021_jslhr-20-00394.
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Purpose This study compares two electromagnetic articulographs manufactured by Northern Digital, Inc.: the NDI Wave System (from 2008) and the NDI Vox-EMA System (from 2020). Method Four experiments were completed: (a) comparison of statically positioned sensors, (b) tracking dynamic movements of sensors manipulated using a motor-driven LEGO apparatus, (c) tracking small and large movements of sensors mounted in a rigid bar manipulated by hand, and (d) tracking movements of sensors rotated on a circular disc. We assessed spatial variability for statically positioned sensors, variability in the transduced Euclidean distances between sensor pairs, and missing data rates. For sensors tracking circular movements, we compared the fit between fitted ideal circles and actual trajectories. Results The average sensor pair tracking error (i.e., the standard deviation of the Euclidean distances) was 1.37 mm for the WAVE and 0.12 mm for the VOX during automated trials at the fastest speed, and 0.35 mm for the WAVE and 0.14 mm for the VOX during the tracking of large manual movements. The average standard deviation of the fitted circle radii charted by manual circular disc movements was 0.72 mm for the WAVE sensors and 0.14 mm for the VOX sensors. There was no significant difference between the WAVE and the VOX in the number of missing frames. Conclusions In general, the VOX system significantly outperformed the WAVE on measures of both static precision and dynamic accuracy (automated and manual). For both systems, positional precision and spatial variability were influenced by the sensors' position relative to the field generator unit (worse when further away). Supplemental Material https://doi.org/10.23641/asha.14787846
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Peach, Leo, N. Carthwright, and D. Strauss. "INVESTIGATING MACHINE LEARNING FOR VIRTUAL WAVE MONITORING." Coastal Engineering Proceedings, no. 36v (December 31, 2020): 46. http://dx.doi.org/10.9753/icce.v36v.papers.46.
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Wave monitoring is a time consuming and costly endeavour which, despite best e orts, can be subject to occasional periods of missing data. This paper investigates the application of machine learning to create "virtual" wave height (Hs), period (Tz) and direction (Dp) parameters. Two supervised machine learning algorithms were applied using long term wave parameter datasets sourced from four wave monitoring stations in relatively close geographic proximity. The machine learning algorithms demonstrated reasonable performance for some parameters through testing, with Hs performing best overall followed closely by Tz; Dp was the most challenging to predict and performed relatively the poorest. The creation of such "virtual" wave monitoring stations could be used to hindcast wave conditions, fill observation gaps or extend data beyond that collected by the physical instrument.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/GM3EG2_SQa0
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Si, Yajuan, Jerome P. Reiter, and D. Sunshine Hillygus. "Semi-parametric Selection Models for Potentially Non-ignorable Attrition in Panel Studies with Refreshment Samples." Political Analysis 23, no. 1 (2015): 92–112. http://dx.doi.org/10.1093/pan/mpu009.
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Panel studies typically suffer from attrition. Ignoring the attrition can result in biased inferences if the missing data are systematically related to outcomes of interest. Unfortunately, panel data alone cannot inform the extent of bias due to attrition. Many panel studies also include refreshment samples, which are data collected from a random sample of new individuals during the later waves of the panel. Refreshment samples offer information that can be utilized to correct for biases induced by non-ignorable attrition while reducing reliance on strong assumptions about the attrition process. We present a Bayesian approach to handle attrition in two-wave panels with one refreshment sample and many categorical survey variables. The approach includes (1) an additive non-ignorable selection model for the attrition process; and (2) a Dirichlet process mixture of multinomial distributions for the categorical survey variables. We present Markov chain Monte Carlo algorithms for sampling from the posterior distribution of model parameters and missing data. We apply the model to correct attrition bias in an analysis of data from the 2007–08 Associated Press/Yahoo News election panel study.
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Aleksandrova, Ekaterina, Christopher J. Gerry, and Olga Verkhovskaya. "Missing entrepreneurs." Journal of Entrepreneurship in Emerging Economies 12, no. 1 (July 22, 2019): 1–33. http://dx.doi.org/10.1108/jeee-11-2018-0133.
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Purpose Compared with other emerging and former command economies, Russia has low levels of entrepreneurial activity and exceptionally low levels of reported entrepreneurial intentions. Drawing on the theory of planned behaviour (TPB), this paper aims to examine the determinants of entrepreneurial intentions in Russia. Design/methodology/approach Using individual level data from two waves (2013 and 2018) of the Global Entrepreneurship Monitor (GEM) survey, the paper presents a range of semi-nonparametric logistic regressions estimating the determinants of reported entrepreneurial intention among the Russian adult population not already engaged in entrepreneurial activity. These data allow for the first empirical exploration of the TPB in the Russian context. Findings The results provide evidence in support of two (“attitudes” and “perceived behavioural control”), from three, origins of the theory of planned behaviour. Firstly, positive attitudes towards entrepreneurship, in the form of employment seeking and direct (own experience) or indirect (experience through social networks) entrepreneurial knowledge are both positively associated with intention. Secondly, individuals who consider their environment to be conducive to entrepreneurship and who believe they have the knowledge and skills required to be entrepreneurs are more likely to intend entrepreneurial action. Originality/value In view of the limited entrepreneurial activity and low levels of reported entrepreneurial intention in Russia, it is important to understand the drivers of these intentions if the appropriate policy responses are to be identified and adopted. This research represents the first substantive efforts to comprehensively examine the determinants of entrepreneurial intentions for Russia and allows us to propose several policy relevant conclusions.
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Su, Yuanda, Xinding Fang, and Xiaoming Tang. "Measurement of the shear slowness of slow formations from monopole logging-while-drilling sonic logs." GEOPHYSICS 85, no. 1 (December 6, 2019): D45—D52. http://dx.doi.org/10.1190/geo2019-0236.1.
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Acoustic logging-while-drilling (LWD) is used to measure formation velocity/slowness during drilling. In a fast formation, in which the S-wave velocity is higher than the borehole-fluid velocity, monopole logging can be used to obtain P- and S-wave velocities by measuring the corresponding refracted waves. In a slow formation, in which the S-wave velocity is less than the borehole-fluid velocity, because the fully refracted S-wave is missing, quadrupole logging has been developed and used for S-wave slowness measurement. A recent study based on numerical modeling implies that monopole LWD can generate a detectable transmitted S-wave in a slow formation. This nondispersive transmitted S-wave propagates at the formation S-wave velocity and thus can be used for measuring the S-wave slowness of a slow formation. We evaluate a field example to demonstrate the applicability of monopole LWD in determining the S-wave slowness of slow formations. We compare the S-wave slowness extracted from a monopole LWD data set acquired in a slow formation and the result derived from the quadrupole data recorded in the same logging run. The results indicated that the S-wave slowness can be reliably determined from monopole LWD sonic data in fairly slow formations. However, we found that the monopole approach is not applicable to very slow formations because the transmitted S-wave becomes too weak to detect when the formation S-wave slowness is much higher than the borehole-fluid slowness.
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Nugroho, Rininta Putri, Anneke Zuiderwijk, Marijn Janssen, and Martin de Jong. "A comparison of national open data policies: lessons learned." Transforming Government: People, Process and Policy 9, no. 3 (August 17, 2015): 286–308. http://dx.doi.org/10.1108/tg-03-2014-0008.
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Purpose – The purpose of this paper is to provide a comprehensive cross-national comparative framework to compare open data policies from different countries and to derive lessons for developing open data policies. Open data policies guide the opening and stimulate the usage of public data. However, some countries have no or less developed open data policies, in this way missing the opportunity to reap the benefits of open data. Design/methodology/approach – Literature review and case studies were conducted to extend an existing comparison framework, and the framework was used to compare open data policies of the UK, the USA, The Netherlands, Kenya and Indonesia. Findings – The comparison of open data policies highlighted several lessons that can be learned, including actions regarding a robust legal framework, generic operational policies, data providers and data users, data quality, designated agencies or taskforces and initiatives and incentives for stimulating demand for data. National policies should also be focused on removing barriers on the operational level and policies for stimulating the release and use of data. Research limitations/implications – There is hardly any research systematically comparing open data policies. The comparative framework provided in this paper is a first analytical basis for cross-national comparison of open data policies and offers possibilities for systematic cross-national lesson-drawing. Practical implications – The authors found two waves of policy-making. The first wave of policy is focused on stimulating the release of data, whereas the second wave of policy is aimed at stimulating use. The comparison can be used to learn from other policies and help to improve open data policies. A third wave of open data policy is expected to materialize focusing on realizing added value from utilizing open data. Social implications – Improving a country’s open data policy can help the country to reap the benefits of open data, such as government transparency, efficiency and economic growth. Originality/value – Open data are a recent phenomenon and countries are looking for ways to obtain the benefits. This research can be used for developing and evaluating open data policies.
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Doidge, James C. "Responsiveness-informed multiple imputation and inverse probability-weighting in cohort studies with missing data that are non-monotone or not missing at random." Statistical Methods in Medical Research 27, no. 2 (March 16, 2016): 352–63. http://dx.doi.org/10.1177/0962280216628902.
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Population-based cohort studies are invaluable to health research because of the breadth of data collection over time, and the representativeness of their samples. However, they are especially prone to missing data, which can compromise the validity of analyses when data are not missing at random. Having many waves of data collection presents opportunity for participants’ responsiveness to be observed over time, which may be informative about missing data mechanisms and thus useful as an auxiliary variable. Modern approaches to handling missing data such as multiple imputation and maximum likelihood can be difficult to implement with the large numbers of auxiliary variables and large amounts of non-monotone missing data that occur in cohort studies. Inverse probability-weighting can be easier to implement but conventional wisdom has stated that it cannot be applied to non-monotone missing data. This paper describes two methods of applying inverse probability-weighting to non-monotone missing data, and explores the potential value of including measures of responsiveness in either inverse probability-weighting or multiple imputation. Simulation studies are used to compare methods and demonstrate that responsiveness in longitudinal studies can be used to mitigate bias induced by missing data, even when data are not missing at random.
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Jewtoukoff, Valérian, Albert Hertzog, Riwal Plougonven, Alvaro de la Cámara, and François Lott. "Comparison of Gravity Waves in the Southern Hemisphere Derived from Balloon Observations and the ECMWF Analyses." Journal of the Atmospheric Sciences 72, no. 9 (September 1, 2015): 3449–68. http://dx.doi.org/10.1175/jas-d-14-0324.1.
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Abstract The increase of spatial resolution allows the ECMWF operational model to explicitly resolve a significant portion of the atmospheric gravity wave (GW) field, but the realism of the simulated GW field in the ECMWF analyses still needs to be precisely evaluated. Here the authors use data collected during the Concordiasi stratospheric balloon campaign to assess the representation of GWs in the ECMWF analyses over Antarctica and the Southern Ocean in spring 2010. The authors first compare the balloonborne GW momentum fluxes with those in ECMWF analyses throughout the campaign and find a correct agreement of the geographical and seasonal patterns. However, the authors also note that ECMWF analyses generally underestimate the balloon fluxes by a factor of 5, which may be essentially due to the spatial truncation of the ECMWF model. Intermittency of wave activity in the analyses and observations are found comparable. These results are confirmed on two case studies dealing with orographic and nonorographic waves, which thus supports that the ECMWF analyses can be used to study the geographical and seasonal distribution of GW momentum fluxes. The authors then used both datasets to provide insights on the missing GW drag at 60°S in general circulation models in the Southern Hemisphere spring. These datasets suggest that a significant part of the missing drag may be associated with nonorographic GWs generated by weather systems above the Southern Ocean.
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Dalmas de Réotier, P., C. Marin, A. Yaouanc, T. Douce, A. Sikora, A. Amato, and C. Baines. "Magnetic Order, Spin Waves and Fluctuations in the Triangular Antiferromagnet La2Ca2MnO7." SPIN 05, no. 02 (June 2015): 1540001. http://dx.doi.org/10.1142/s2010324715400019.
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We report magnetic susceptibility, specific heat and muon spin relaxation (μSR) experiments on the triangular antiferromagnet La 2 Ca 2 MnO 7 which develops a genuine two-dimensional (2D), three-sublattice [Formula: see text] magnetic order below T N = 2.8 K. From the susceptibility and specific heat an estimate of the exchange interaction is derived. A value for the spin-wave gap is obtained from the latter data. The analysis of a previously reported inelastic neutron scattering data yields values for the exchange and spin-wave gap compatible with the results obtained from macroscopic measurements. An appreciable entropy is still missing at 10 K that may be ascribed to intense short-range correlations. The critical paramagnetic fluctuations extend far above T N , and can be partly understood in terms of two-dimensional spin-wave excitations. While no spontaneous μSR field is observed below T N , persistent spin dynamics is found. Short-range correlations are detected in this temperature range. Their relation to a possible molecular spin substructure and the observed exotic spin fluctuations is discussed.
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Bao, Runjia, Junkui Wei, Bowen Li, and Ximeng Chen. "Electron-Impact Ionization of the Tungsten Ions: W38- W45++." Atoms 10, no. 3 (September 9, 2022): 92. http://dx.doi.org/10.3390/atoms10030092.
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In this manuscript, we present our calculations of detailed electron-impact single ionization cross-sections for tungsten ions, spanning charge states W38+− W45+. The level-to-level distorted-wave method implemented in the flexible atomic code (FAC) was used for calculation. Comparison between the present level-to-level distorted wave treatment and previous configuration-averaged calculations has been performed for the W45+ ion, and we explore the possible reason for the difference observed between two calculations. We demonstrate the importance of radiative damping on the total electron-impact ionization cross-section for the W43+ ion. Present calculations provide missing cross-sections for W38+− W45+. The data obtained are expected to be useful for modeling plasmas for fusion applications, especially for the ITER community.
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Wu, Juan, and Min Bai. "Adaptive rank-reduction method for seismic data reconstruction." Journal of Geophysics and Engineering 15, no. 4 (May 16, 2018): 1688–703. http://dx.doi.org/10.1093/jge/aabc74.
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Abstract Seismic data reconstruction plays an important role in the whole seismic data processing and imaging workflow, especially for those data that are acquired from severe field environment and are missing a large portion of the reflection signals. The rank-reduction method is considered to be a very effective method for interpolating data that are of small curvature, e.g. the post-stack data. However, when the data are more complicated, the rank-reduction method may fail to achieve acceptable performance. A useful strategy is to use local windows to process the data so that the data in each local window satisfy the plane-wave assumption of the rank-reduction method. However, the rank in each window requires a careful selection. Traditional methods select a global rank for all windows. We have proposed an automatic algorithm to select the rank in each processing window. The energy ratio between two consecutive singular values is chosen as the criterion to define the optimal rank. We apply this strategy to seismic data interpolation and use both synthetic and field data examples to demonstrate its potential in practical applications.
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Santoso, Purwoko Haryadi, Edi Istiyono, and Haryanto Haryanto. "Principal Component Analysis and Exploratory Factor Analysis of the Mechanical Waves Conceptual Survey." JP3I (Jurnal Pengukuran Psikologi dan Pendidikan Indonesia) 11, no. 2 (November 25, 2022): 209–25. http://dx.doi.org/10.15408/jp3i.v11i2.27488.
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Mechanical waves conceptual survey (MWCS) is a measurement tool established by the physics education research (PER) community to evaluate conceptual physics understanding of mechanical waves. A validation study is still needed to figure out the factor structure of MWCS using two data reduction techniques, namely exploratory factor analysis (EFA) and principal component analysis (PCA). The MWCS dataset in this paper was gathered from physics students (n = 419) from nineteen Ugandan secondary schools. The findings of this research suggested the single factor of the MWCS construct that has emerged from the dataset explored in this study. Several issues involved in the calculation of inter-item correlation within the dataset are suspected as the leading cause of the missing component solution or stable loading in the data. Moreover, there might be other issues that leave open space for future exploration. The findings reported in this paper could be the subject of further discussion in evaluating the validity of the MWCS as a research-based assessment (RBA) to measure students' conceptual understanding of wave mechanics within PER studies.
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Huang, Bolin, Yueping Yin, Shichang Wang, Jianmin Tan, and Guangning Liu. "Analysis of the Tangjiaxi landslide-generated waves in the Zhexi Reservoir, China, by a granular flow coupling model." Natural Hazards and Earth System Sciences 17, no. 5 (May 11, 2017): 657–70. http://dx.doi.org/10.5194/nhess-17-657-2017.
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Abstract. A rocky granular flow is commonly formed after the failure of rocky bank slopes. An impulse wave disaster may also be initiated if the rocky granular flow rushes into a river with a high velocity. Currently, the granular mass–water body coupling study is an important trend in the field of landslide-induced impulse waves. In this paper, a full coupling numerical model for landslide-induced impulse waves is developed based on a non-coherent granular flow equation, i.e., the Mih equation. In this model, the Mih equation for continuous non-coherent granular flow controls movements of sliding mass, the two-phase flow equation regulates the interaction between sliding mass and water, and the renormalization group (RNG) turbulence model governs the movement of the water body. The proposed model is validated and applied for the 2014 Tangjiaxi landslide of the Zhexi Reservoir located in Hunan Province, China, to analyze the characteristics of both landslide motion and its following impulse waves. On 16 July 2014, a rocky debris flow was formed after the failure of the Tangjiaxi landslide, damming the Tangjiaxi stream and causing an impulse wave disaster with three dead and nine missing bodies. Based on the full coupling numerical analysis, the granular flow impacts the water with a maximum velocity of about 22.5 m s−1. Moreover, the propagation velocity of the generated waves reaches up to 12 m s−1. The maximum calculated run-up of 21.8 m is close enough to the real value of 22.7 m. The predicted landslide final deposit and wave run-up heights are in a good agreement with the field survey data. These facts verify the ability of the proposed model for simulating the real impulse wave generated by rocky granular flow events.
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Oropeza, Vicente, and Mauricio Sacchi. "Simultaneous seismic data denoising and reconstruction via multichannel singular spectrum analysis." GEOPHYSICS 76, no. 3 (May 2011): V25—V32. http://dx.doi.org/10.1190/1.3552706.
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We present a rank reduction algorithm that permits simultaneous reconstruction and random noise attenuation of seismic records. We based our technique on multichannel singular spectrum analysis (MSSA). The technique entails organizing spatial data at a given temporal frequency into a block Hankel matrix that in ideal conditions is a matrix of rank [Formula: see text], where [Formula: see text] is the number of plane waves in the window of analysis. Additive noise and missing samples will increase the rank of the block Hankel matrix of the data. Consequently, rank reduction is proposed as a means to attenuate noise and recover missing traces. We present an iterative algorithm that resembles seismic data reconstruction with the method of projection onto convex sets. In addition, we propose to adopt a randomized singular value decomposition to accelerate the rank reduction stage of the algorithm. We apply MSSA reconstruction to synthetic examples and a field data set. Synthetic examples were used to assess the performance of the method in two reconstruction scenarios: a noise-free case and data contaminated with noise. In both cases, we found extremely low reconstructions errors that are indicative of an optimal recovery. The field data example consists of a 2D prestack volume that depends on common midpoint and offset. We use the MSSA reconstruction method to complete missing offsets and, at the same time, increase the signal-to-noise ratio of the seismic volume.
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Kidambi Sekar, A. P., M. F. van Dooren, and M. Kühn. "Overcoming Blade Interference: A Gappy-POD Data Reconstruction Method for Nacelle-Mounted Lidar Measurements." Journal of Physics: Conference Series 2265, no. 2 (May 1, 2022): 022078. http://dx.doi.org/10.1088/1742-6596/2265/2/022078.
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Abstract Nacelle-mounted lidar systems suffer data loss due to unfavourable atmospheric conditions such as rain or fog and most importantly the rotation of the blades that obstruct the laser beam from measuring upstream of the turbine. In this paper, we apply Gappy Proper Orthogonal Decomposition (Gappy-POD) to reconstruct incomplete flow fields from nacelle-mounted lidar measurements. For this purpose, two scanning nacelle-based SpinnerLidar simulations are performed inside a Large Eddy Simulation, one measuring the undisturbed wind inflow and the other in the wake of a reference turbine. Data loss of up to 90 % is simulated by artificially removing measurement points. The performance of Gappy-POD in reconstructing the wind fields is evaluated by comparing metrics such as effective wind speeds, vertical shear, yaw misalignment, wake deficit, wake meandering and the turbulent spectra in fixed and rotating frames of reference. We see that Gappy-POD is capable of accurately reconstructing missing data in comparison to normally used spatial interpolation techniques even in cases where 90 % of the data was missing. As a result, the dynamics of the reconstructed wind fields can be investigated based on highly accurate lidar-based wind field retrievals. The methodology can be used as a tool to develop effective wind field reconstruction techniques from sparse data.
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Ern, Manfred, Mohamadou Diallo, Peter Preusse, Martin G. Mlynczak, Michael J. Schwartz, Qian Wu, and Martin Riese. "The semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observations." Atmospheric Chemistry and Physics 21, no. 18 (September 16, 2021): 13763–95. http://dx.doi.org/10.5194/acp-21-13763-2021.
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Abstract. Gravity waves play a significant role in driving the semiannual oscillation (SAO) of the zonal wind in the tropics. However, detailed knowledge of this forcing is missing, and direct estimates from global observations of gravity waves are sparse. For the period 2002–2018, we investigate the SAO in four different reanalyses: ERA-Interim, JRA-55, ERA-5, and MERRA-2. Comparison with the SPARC zonal wind climatology and quasi-geostrophic winds derived from Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite observations show that the reanalyses reproduce some basic features of the SAO. However, there are also large differences, depending on the model setup. Particularly, MERRA-2 seems to benefit from dedicated tuning of the gravity wave drag parameterization and assimilation of MLS observations. To study the interaction of gravity waves with the background wind, absolute values of gravity wave momentum fluxes and a proxy for absolute gravity wave drag derived from SABER satellite observations are compared with different wind data sets: the SPARC wind climatology; data sets combining ERA-Interim at low altitudes and MLS or SABER quasi-geostrophic winds at high altitudes; and data sets that combine ERA-Interim, SABER quasi-geostrophic winds, and direct wind observations by the TIMED Doppler Interferometer (TIDI). In the lower and middle mesosphere the SABER absolute gravity wave drag proxy correlates well with positive vertical gradients of the background wind, indicating that gravity waves contribute mainly to the driving of the SAO eastward wind phases and their downward propagation with time. At altitudes 75–85 km, the SABER absolute gravity wave drag proxy correlates better with absolute values of the background wind, suggesting a more direct forcing of the SAO winds by gravity wave amplitude saturation. Above about 80 km SABER gravity wave drag is mainly governed by tides rather than by the SAO. The reanalyses reproduce some basic features of the SAO gravity wave driving: all reanalyses show stronger gravity wave driving of the SAO eastward phase in the stratopause region. For the higher-top models ERA-5 and MERRA-2, this is also the case in the lower mesosphere. However, all reanalyses are limited by model-inherent damping in the upper model levels, leading to unrealistic features near the model top. Our analysis of the SABER and reanalysis gravity wave drag suggests that the magnitude of SAO gravity wave forcing is often too weak in the free-running general circulation models; therefore, a more realistic representation is needed.
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Piorecky, Marek, Vlastimil Koudelka, Vaclava Piorecka, Jan Strobl, Daniela Dudysova, and Jana Koprivova. "Real-Time Excitation of Slow Oscillations during Deep Sleep Using Acoustic Stimulation." Sensors 21, no. 15 (July 30, 2021): 5169. http://dx.doi.org/10.3390/s21155169.
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Slow-wave synchronous acoustic stimulation is a promising research and therapeutic tool. It is essential to clearly understand the principles of the synchronization methods, to know their performances and limitations, and, most importantly, to have a clear picture of the effect of stimulation on slow-wave activity (SWA). This paper covers the mentioned and currently missing parts of knowledge that are essential for the appropriate development of the method itself and future applications. Artificially streamed real sleep EEG data were used to quantitatively compare the two currently used real-time methods: the phase-locking loop (PLL) and the fixed-step stimulus in our own implementation. The fixed-step stimulation method was concluded to be more reliable and practically applicable compared to the PLL method. The sleep experiment with chronic insomnia patients in our sleep laboratory was analyzed in order to precisely characterize the effect of sound stimulation during deep sleep. We found that there is a significant phase synchronization of delta waves, which were shown to be the most sensitive metric of the effect of acoustic stimulation compared to commonly used averaged signal and power analyses. This finding may change the understanding of the effect and function of the SWA stimulation described in the literature.
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Renna, Francesco. "Alcohol Abuse, Alcoholism, and Labor Market Outcomes: Looking for the Missing Link." ILR Review 62, no. 1 (October 2008): 92–103. http://dx.doi.org/10.1177/001979390806200105.
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There is puzzling evidence that alcohol abuse and alcoholism reduce labor earnings but have no effect on either hours worked or the hourly wage. This study revisits the link between problem drinking and earnings using data from the 1989 and 1994 waves of the National Longitudinal Survey of Youth. Questions about problem drinking were keyed to a table of symptoms for alcohol abuse and alcoholism in the Diagnostic and Statistical Manual of Mental Disorders. The author finds no effects associated with alcohol abuse. In OLS regressions, alcoholism appears to have had negative effects on both labor market outcomes. In the lag variable and in the first difference regressions, alcoholism's negative effect on wages disappears, but its negative effect on hours of work remains, suggesting that the negative effect of alcoholism on earnings operates through reduced work hours. These results of the two-stage least squares are inconclusive.
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Li, Xiang, Aleksandr Y. Aravkin, Tristan van Leeuwen, and Felix J. Herrmann. "Fast randomized full-waveform inversion with compressive sensing." GEOPHYSICS 77, no. 3 (May 1, 2012): A13—A17. http://dx.doi.org/10.1190/geo2011-0410.1.
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Wave-equation-based seismic inversion can be formulated as a nonlinear least-squares problem. The demand for higher-resolution models in more geologically complex areas drives the need to develop techniques that exploit the special structure of full-waveform inversion to reduce the computational burden and to regularize the inverse problem. We meet these goals by using ideas from compressive sensing and stochastic optimization to design a novel Gauss-Newton method, where the updates are computed from random subsets of the data via curvelet-domain sparsity promotion. Two different subset sampling strategies are considered: randomized source encoding, and drawing sequential shots firing at random source locations from marine data with missing near and far offsets. In both cases, we obtain excellent inversion results compared to conventional methods at reduced computational costs.
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Patrick, Carlianne, and Heather M. Stephens. "Incentivizing the Missing Middle: The Role of Economic Development Policy." Economic Development Quarterly 34, no. 2 (February 28, 2020): 154–70. http://dx.doi.org/10.1177/0891242420907160.
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The shrinking middle class and increasing income polarization in the United States are issues of concern to policy makers and others. Economic development incentives are a key policy tool used at the state and local levels to promote local economic growth, and, presumably, provide employment opportunities. However, these incentives may have unintended consequences that may be contributing to the decline of the middle class. The authors combine detailed industry-level detail on incentives with proprietary county-level industry employment data and two methods for defining middle-class industries. Using an instrumental variable approach, the authors estimate how differential economic development policies affect middle-class jobs. The authors find evidence that incentivizing creative-class and high-wage industries may be contributing to the hollowing out of the middle class. Without hurting employment in other industries, targeting working-class and middle-wage industries alleviates this trend, while reducing incentives on creative-class and high-wage industries could help increase working and middle-class employment.
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Zimmaro, Paolo, Dong Youp Kwak, Yi Tyan Tsai, Jonathan P. Stewart, Scott J. Brandenberg, Atsushi Mikami, and Shojiro Kataoka. "Database on seismic response of instrumented flood control levees." Earthquake Spectra 36, no. 2 (January 31, 2020): 924–38. http://dx.doi.org/10.1177/8755293019891712.
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We present a database documenting the seismic response of seven instrumented flood control levee segments in Japan. The database includes (1) maps and cross-sections showing levee geometry and instrument layouts; (2) ground motion time series, and (where available) piezometric recordings; (3) reported field performance from post-earthquake reconnaissance (i.e. permanent displacements, other evidence of ground failure); and (4) geotechnical data, including geologic cross-sections, stratigraphy, penetration resistance, and shear wave velocity ( VS) profiles. The data are complete with respect to these attributes for three sites, with geotechnical data and field performance data missing for two and four sites, respectively. The database contains 150 recordings from 25 events and can be accessed through DOI: 10.21222/C2TC95. Ground motions were processed using standard procedures for Next Generation Attenuation projects. We present example data for a segment damaged by the M9.1 2011 Tohoku-oki earthquake, which includes ground motion and pore water pressure measurements.
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Balasis, G., I. A. Daglis, E. Zesta, C. Papadimitriou, M. Georgiou, R. Haagmans, and K. Tsinganos. "ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions." Annales Geophysicae 30, no. 12 (December 21, 2012): 1751–68. http://dx.doi.org/10.5194/angeo-30-1751-2012.
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Abstract. We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting from the region of topside ionosphere, we first present three clear and strong signatures of Pc3 ULF wave activity (frequency 15–100 mHz) in CHAMP tracks. We then expand these three time intervals for purposes of comparison between CHAMP, Cluster and Geotail Pc3 observations but also to be able to search for Pc4–5 wave signatures (frequency 1–10 mHz) into Cluster and Geotail measurements in order to have a more complete picture of the ULF wave occurrence during the storm. Due to the fast motion through field lines in a low Earth orbit (LEO) we are able to reliably detect Pc3 (but not Pc4–5) waves from CHAMP. This is the first time, to our knowledge, that ULF wave observations from a topside ionosphere mission are compared to ULF wave observations from magnetospheric missions. Our study provides evidence for the occurrence of a number of prominent ULF wave events in the Pc3 and Pc4–5 bands during the storm and offers a platform to study the wave evolution from high altitudes to LEO. The ULF wave analysis methods presented here can be applied to observations from the upcoming Swarm multi-satellite mission of ESA, which is anticipated to enable joint studies with the Cluster mission.
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Akbar, Nabil, Gary Mavko, Amos Nur, and Jack Dvorkin. "Seismic signatures of reservoir transport properties and pore fluid distribution." GEOPHYSICS 59, no. 8 (August 1994): 1222–36. http://dx.doi.org/10.1190/1.1443680.
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We investigate the effects of permeability, frequency, and fluid distribution on the viscoelastic behavior of rock. The viscoelastic response of rock to seismic waves depends on the relative motion of pore fluid with respect to the solid phase. Fluid motion depends, in part, on the internal wave‐induced pore pressure distribution that relates to the pore micro‐structure of rock and the scales of saturation. We consider wave‐induced squirt fluid flow at two scales: (1) local microscopic flow at the smallest scale of saturation heterogeneity (e.g., within a single pore) and (2) macroscopic flow at a larger scale of fluid‐saturated and dry patches. We explore the circumstances under which each of these mechanisms prevails. We examine such flows under the conditions of uniform confining (bulk) compression and obtain the effective dynamic bulk modulus of rock. The solutions are formulated in terms of generalized frequencies that depend on frequency, saturation, fluid and gas properties, and on the macroscopic properties of rock such as permeability, porosity, and dry bulk modulus. The study includes the whole range of saturation and frequency; therefore, we provide the missing link between the low‐frequency limit (Gassmann’s formula) and the high‐frequency limit given by Mavko and Jizba. Further, we compare our model with Biot’s theory and introduce a geometrical factor whose numeric value gives an indication as to whether local fluid squirt or global (squirt and/or Biot’s) mechanisms dominate the viscoelastic properties of porous materials. The important results of our theoretical modeling are: (1) a hysteresis of acoustic velocity versus saturation resulting from variations in fluid distributions, and (2) two peaks of acoustic wave attenuation—one at low frequency (caused by global squirt‐flow) and another at higher frequency (caused by local flow). Both theoretical results are compared with experimental data.
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Robins, Thomas, Jorge Camacho, Oscar Calderon Agudo, Joaquin L. Herraiz, and Lluís Guasch. "Deep-Learning-Driven Full-Waveform Inversion for Ultrasound Breast Imaging." Sensors 21, no. 13 (July 3, 2021): 4570. http://dx.doi.org/10.3390/s21134570.
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Ultrasound breast imaging is a promising alternative to conventional mammography because it does not expose women to harmful ionising radiation and it can successfully image dense breast tissue. However, conventional ultrasound imaging only provides morphological information with limited diagnostic value. Ultrasound computed tomography (USCT) uses energy in both transmission and reflection when imaging the breast to provide more diagnostically relevant quantitative tissue properties, but it is often based on time-of-flight tomography or similar ray approximations of the wave equation, resulting in reconstructed images with low resolution. Full-waveform inversion (FWI) is based on a more accurate approximation of wave-propagation phenomena and can consequently produce very high resolution images using frequencies below 1 megahertz. These low frequencies, however, are not available in most USCT acquisition systems, as they use transducers with central frequencies well above those required in FWI. To circumvent this problem, we designed, trained, and implemented a two-dimensional convolutional neural network to artificially generate missing low frequencies in USCT data. Our results show that FWI reconstructions using experiment data after the application of the proposed method successfully converged, showing good agreement with X-ray CT and reflection ultrasound-tomography images.
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Konrad-Martin, Dawn, Marilyn F. Dille, Garnett McMillan, Susan Griest, Daniel McDermott, Stephen A. Fausti, and Donald F. Austin. "Age-Related Changes in the Auditory Brainstem Response." Journal of the American Academy of Audiology 23, no. 01 (January 2012): 018–35. http://dx.doi.org/10.3766/jaaa.23.1.3.
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Purpose: This cross-sectional study had two goals: (1) Identify and quantify the effects of aging on the auditory brainstem response (ABR); (2) Describe how click rate and hearing impairment modify effects of aging. Research Design and Analysis: ABR measures were obtained from 131 predominately male Veteran participants aged 26 to 71 yr. Metrics analyzed include amplitude and latency for waves I, III, and V, and the I–V interpeak latency interval (IPI) at three repetition rates (11, 51, and 71 clicks/sec) using both polarities. In order to avoid confounding from missing data due to hearing impairment, participants had hearing thresholds <40 dB HL at 2 kHz and 70 dB HL at 4 kHz in at least one ear. Additionally, the median 2, 3, and 4 kHz pure tone threshold average (PTA2,3,4) for the sample, ˜17 dB HL, was used to delineate subgroups of better and worse hearing ears, and only the better hearing sample was modeled statistically. We modeled ABR responses using age, repetition rate, and PTA2,3,4 as covariates. Random effects were used to model correlation between the two ears of a subject and across repetition rates. Inferences regarding effects of aging on ABR measures at each rate were derived from the fitted model. Results were compared to data from subjects with poorer hearing. Results: Aging substantially diminished amplitudes of all of the principal ABR peaks, largely independent of any threshold differences within the group. For waves I and III, age-related amplitude decrements were greatest at a low (11/sec) click rate. At the 11/sec rate, the model-based mean wave III amplitude was significantly smaller in older compared with younger subjects even after adjusting for wave I amplitude. Aging also increased ABR peak latencies, with significant shifts limited to early waves. The I–V IPI did not change with age. For both younger and older subjects, increasing click presentation rate significantly decreased amplitudes of early peaks and prolonged latencies of later peaks, resulting in increased IPIs. Advanced age did not enhance effects of rate. Instead, the rate effect on wave I and III amplitudes was attenuated for the older subjects due to reduced peak amplitudes at lower click rates. Compared with model predictions from the sample of better hearing subjects, mean ABR amplitudes were diminished in the group with poorer hearing, and wave V latencies were prolonged. Conclusions: In a sample of veterans, aging substantially reduced amplitudes of all principal ABR peaks, with significant latency shifts limited to waves I and III. Aging did not influence the I–V IPI even at high click rates, suggesting that the observed absolute latency changes associated with aging can be attributed to changes in auditory nerve input. In contrast, ABR amplitude changes with age are not adequately explained by changes in wave I. Results suggest that aging reduces the numbers and/or synchrony of contributing auditory nerve units. Results also support the concept that aging reduces the numbers, though perhaps not the synchrony, of central ABR generators.
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Sacchi, Mauricio D., and Tadeusz J. Ulrych. "Estimation of the discrete Fourier transform, a linear inversion approach." GEOPHYSICS 61, no. 4 (July 1996): 1128–36. http://dx.doi.org/10.1190/1.1444033.
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Spatio‐temporal analysis of seismic records is of particular relevance in many geophysical applications, e.g., vertical seismic profiles, plane‐wave slowness estimation in seismographic array processing and in sonar array processing. The goal is to estimate from a limited number of receivers the 2-D spectral signature of a group of events that are recorded on a linear array of receivers. When the spatial coverage of the array is small, conventional f-k analysis based on Fourier transform leads to f-k panels that are dominated by sidelobes. An algorithm that uses a Bayesian approach to design an artifacts‐reduced Fourier transform has been developed to overcome this shortcoming. A by‐product of the method is a high‐resolution periodogram. This extrapolation gives the periodogram that would have been recorded with a longer array of receivers if the data were a limited superposition of monochromatic planes waves. The technique is useful in array processing for two reasons. First, it provides spatial extrapolation of the array (subject to the above data assumption) and second, missing receivers within and outside the aperture are treated as unknowns rather than as zeros. The performance of the technique is illustrated with synthetic examples for both broad‐band and narrow‐band data. Finally, the applicability of the procedure is assessed analyzing the f-k spectral signature of a vertical seismic profile (VSP).
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Kaczmarczyk, Weronika, and Andrzej Brodzicki. "Wykorzystanie technik sztucznych sieci neuronowych do predykcji wybranych parametrów jako uzupełnienia zbioru danych wejściowych w konstrukcji modeli parametrycznych 3D." Nafta-Gaz 77, no. 7 (July 2021): 429–45. http://dx.doi.org/10.18668/ng.2021.07.02.
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The article presents the possibilities of using artificial neural networks for parametric prediction in borehole profiles, the application of which supplemented the set of information in all boreholes located within the analyzed area. The approach presented in the article will be used when there is no possibility of specialized interpretation of the drilling geophysics curves, supplementing the missing data. The set of data used in the study included solutions in the profiles of 10 boreholes, four of which were characterized by the availability of the full data set analyzed in this article, including compressional wave velocity, effective porosity, hydrocarbon saturation, Young’s modulus and Poisson’s ratio. Using the technique of the operation of artificial neural networks, a prediction of missing information was carried out based on the relationships between the analyzed parameters in the wells, where the estimated data was available. In recent years, there has been a dynamic development of machine learning technology and the so-called artificial intelligence. There are very few fields of science in which they find no application. The hydrocarbon saturation parameter, despite the challenges posed by the interpretation of this parameter, was also subjected to an estimation attempt, confirming the low correlation values between the analyzed parameters and requiring much more advanced work of an individual nature. The results of parametric prediction, previously validated by characterizing the R and RMSE parameters, were applied in the next step in the spatial modeling process of all analyzed parameters. Finally, as part of the visualization of the differences between the use of an incomplete and partially estimated data set in spatial analysis, a map of mean values of the selected parameter within the analyzed interval was presented. The set of data prepared in this way allowed for a more reliable spatial reconstruction of the distribution of parameters important in the context of the characteristics of the hydrocarbon reservoir, on the basis of which, in the subsequent stages, it is possible to more fully assess the deposit potential of the analyzed object. The methodology presented in the article, supported by a real case study, is an alternative to geophysical interpretations that require financial and time resources, sometimes large numbers of boreholes, especially for areas characterized by relatively low spatial variability and tectonic complexity. The condition is the availability of the interpretation in at least several boreholes, constituting a pattern for recreating the variability of the tested parameter / parameters in the remaining profiles of the boreholes.
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Jankowsky, Kristin, and Ulrich Schroeders. "Validation and generalizability of machine learning prediction models on attrition in longitudinal studies." International Journal of Behavioral Development 46, no. 2 (February 7, 2022): 169–76. http://dx.doi.org/10.1177/01650254221075034.
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Attrition in longitudinal studies is a major threat to the representativeness of the data and the generalizability of the findings. Typical approaches to address systematic nonresponse are either expensive and unsatisfactory (e.g., oversampling) or rely on the unrealistic assumption of data missing at random (e.g., multiple imputation). Thus, models that effectively predict who most likely drops out in subsequent occasions might offer the opportunity to take countermeasures (e.g., incentives). With the current study, we introduce a longitudinal model validation approach and examine whether attrition in two nationally representative longitudinal panel studies can be predicted accurately. We compare the performance of a basic logistic regression model with a more flexible, data-driven machine learning algorithm—gradient boosting machines. Our results show almost no difference in accuracies for both modeling approaches, which contradicts claims of similar studies on survey attrition. Prediction models could not be generalized across surveys and were less accurate when tested at a later survey wave. We discuss the implications of these findings for survey retention, the use of complex machine learning algorithms, and give some recommendations to deal with study attrition.
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Seblova, Dominika, Marie Kuklova, Miloslav Kopecek, Pavla Cermakova, Carol Brayne, and Vendula Machu. "NINE YEAR CHANGES IN PREVALENCE OF COGNITIVE IMPAIRMENT IN THE CZECH REPUBLIC." Innovation in Aging 3, Supplement_1 (November 2019): S865—S866. http://dx.doi.org/10.1093/geroni/igz038.3178.
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Abstract Studies from North America and Western Europe suggest stable or declining trends in impaired cognition. Nevertheless, data on changes in cognitive health from Central and Eastern Europe are largely lacking. Therefore, we aimed to examine changes in the age-specific prevalence of cognitive impairment in the Czech Republic, a country in Central Europe. To this aim we used two samples from the population-based Czech Survey on Health, Ageing and Retirement in Europe (SHARE). Age-specific prevalence of cognitive impairment (defined based on scores in verbal fluency, immediate recall, delayed recall and temporal orientation) was compared between participants in wave 2 (2006/2007; n=1,107) and wave 6 (2015; n=3,104). Logistic regression was used to estimate the association between wave and cognitive impairment, step-wise adjusting for sociodemographic and clinical characteristics. Multiple sensitivity analyses, focusing on alternative operationalisations of relative cognitive impairment, impact of missing cognitive data and survival bias, were carried out. The most conservative estimate suggested that the age-specific prevalence of cognitive impairment declined by one fifth, from 11% in 2006/2007 to 9% in 2015. Decline was observed in all sensitivity analyses. Multivariate decomposition for nonlinear models was used to examine which predictors explain the change in prevalence. Reduction in physical inactivity, control of high blood cholesterol and increases in length of education were the main predictors contributing to decline in cognitive impairment. In conclusion, our findings are in line with those found in North America and Western Europe even though countries in Central and Eastern Europe, including Czech Republic, have poorer risk profiles.
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Macrides, Costas G., and Fernando A. Neves. "Lithology estimation from a multicomponent 3D-4C OBC seismic survey over a clastic reservoir in the Arabian Gulf." GeoArabia 13, no. 1 (January 1, 2008): 15–34. http://dx.doi.org/10.2113/geoarabia130115.
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ABSTRACT In 2002, Saudi Aramco conducted its first 3D, 4-component (4C) ocean-bottom cable (OBC) seismic survey in the Arabian Gulf. The main objective was to delineate the middle Cretaceous Upper Khafji Sand Stringers Reservoir overlying the massive Main Khafji Sand Reservoir in the Zuluf field. The Upper Khafji Sand Stringers Reservoir in the Wasia Formation is typically characterized by weak acoustic impedance contrasts. A pre-survey modeling study, based on the logs of compressional (P) and shear-wave (S) velocities (Vp and Vs), indicated that converted compressional-to-shear waves (P-S) could better-image the structure and stratigraphy of the target reservoir. Commensurate with the objectives of the experiment, a pilot 100-square-kilometer survey was acquired with an inline swath-shooting geometry that employed two seabed receiver cables, with a symmetric split-spread deployment of the 4-C sensors. The acquisition geometry consisted of six sail lines per swath with a single-boat, dual-source, flip-flop configuration. The data were processed through dual-sensor summation, horizontal-component rotation and P-P/P-S pre-stack time migration. Post-stack enhancement using non-stationary Gabor deconvolution proved beneficial in compensating for the missing high frequencies in the acquired converted-wave data. Well-to-seismic calibration for both P-P and P-S data at five wells aided in the interpretation of the data. Five horizons were interpreted and correlated between the P-P and P-S sections. The horizons were analyzed using both amplitude and interval times such that the lateral variations of the Vp/Vs ratio of the Upper Khafji Sand Stringers Reservoir could be mapped. A region of low Vp/Vs ratios in the northwest quadrant, obtained from the isochron interval-time analysis, was correlated with higher ‘net sand’ pay at a hidden well located in the middle of this region. These results were further corroborated by seismic facies analysis and provide a qualitative reservoir quality index in the Upper Khafji Sand Stringers Reservoir.
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Li, Yunyue Elita, and Laurent Demanet. "Full-waveform inversion with extrapolated low-frequency data." GEOPHYSICS 81, no. 6 (November 2016): R339—R348. http://dx.doi.org/10.1190/geo2016-0038.1.
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The availability of low-frequency data is an important factor in the success of full-waveform inversion (FWI) in the acoustic regime. The low frequencies help determine the kinematically relevant, low-wavenumber components of the velocity model, which are in turn needed to avoid convergence of FWI to spurious local minima. However, acquiring data less than 2 or 3 Hz from the field is a challenging and expensive task. We have explored the possibility of synthesizing the low frequencies computationally from high-frequency data and used the resulting prediction of the missing data to seed the frequency sweep of FWI. As a signal-processing problem, bandwidth extension is a very nonlinear and delicate operation. In all but the simplest of scenarios, it can only be expected to lead to plausible recovery of the low frequencies, rather than their accurate reconstruction. Even so, it still requires a high-level interpretation of band-limited seismic records into individual events, each of which can be extrapolated to a lower (or higher) frequency band from the nondispersive nature of the wave-propagation model. We have used the phase-tracking method for the event separation task. The fidelity of the resulting extrapolation method is typically higher in phase than in amplitude. To demonstrate the reliability of bandwidth extension in the context of FWI, we first used the low frequencies in the extrapolated band as data substitute, to create the low-wavenumber background velocity model, and then we switched to recorded data in the available band for the rest of the iterations. The resulting method, extrapolated FWI, demonstrated surprising robustness to the inaccuracies in the extrapolated low-frequency data. With two synthetic examples calibrated so that regular FWI needs to be initialized at 1 Hz to avoid local minima, we have determined that FWI based on an extrapolated [1, 5] Hz band, itself generated from data available in the [5, 15] Hz band, can produce reasonable estimations of the low-wavenumber velocity models.
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Delva, P., C. Le Poncin-Lafitte, P. Laurent, F. Meynadier, and P. Wolf. "Time and frequency transfer with the ESA/CNES ACES-PHARAO mission." Proceedings of the International Astronomical Union 10, H16 (August 2012): 211–12. http://dx.doi.org/10.1017/s1743921314005456.
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AbstractWe have written a theoretical description of one-way and two-way satellite time and frequency transfer and developed a model of the micro-wave link in the frame of the ACES/PHARAO mission. This is used to write a data analysis software and a simulation to test it. A very short description of the mission and of the micro-wave link is given here. A detailed description can be found in Delva et al., 2012, Proceedings of the EFTF, Gothenburg, Sweden, arXiv:1206.6239.
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PRATSCHKE, JONATHAN, TRUTZ HAASE, and KIERAN McKEOWN. "Direct and indirect influences of socio-economic position on the wellbeing of older adults: a Structural Equation Model using data from the first wave of the Irish Longitudinal Study on Ageing." Ageing and Society 37, no. 9 (June 20, 2016): 1770–97. http://dx.doi.org/10.1017/s0144686x1600060x.
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ABSTRACTThe authors use Structural Equation Modelling techniques to analyse the determinants of wellbeing amongst older adults using data from the first wave of the Irish Longitudinal Study on Ageing (TILDA), a rich source of data on people aged over 50 and living in private households. The analysis uses a two-group linear statistical model to explore the influence of socio-economic position on the wellbeing of men and women, with Full Information Maximum Likelihood estimation to handle missing data. The fit indices for the final model are highly satisfactory and the measurement structure is invariant by gender and age. The results indicate that socio-economic position has a significant direct influence on wellbeing and a strong indirect influence which is mediated by health status and lifestyle. The total standardised effect of Socio-economic Position on Socio-emotional Wellbeing is statistically significant (p⩽ 0.05) and equal to 0.32 (men) and 0.43 (women), a very strong influence which risks being underestimated in standard multivariate models. The authors conclude that health, cognitive functioning and wellbeing reflect not just the ageing process, but also the impact of social inequalities across the lifecourse and how they are transmitted across different life spheres. These results can help to orient future research on factors which mediate between socio-economic position and wellbeing, an important policy-related issue.
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Podglajen, Aurélien, Albert Hertzog, Riwal Plougonven, and Bernard Legras. "Lagrangian gravity wave spectra in the lower stratosphere of current (re)analyses." Atmospheric Chemistry and Physics 20, no. 15 (August 10, 2020): 9331–50. http://dx.doi.org/10.5194/acp-20-9331-2020.
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Abstract. Due to their increasing spatial resolution, numerical weather prediction (NWP) models and the associated analyses resolve a growing fraction of the gravity wave (GW) spectrum. However, it is unclear how well this “resolved” part of the spectrum truly compares to the actual atmospheric variability. In particular, the Lagrangian variability, relevant, for example, to atmospheric dispersion and to microphysical modeling in the upper troposphere–lower stratosphere (UTLS), has not yet been documented in recent products. To address this shortcoming, this paper presents an assessment of the GW spectrum as a function of the intrinsic (air parcel following) frequency in recent (re)analyses (ERA-Interim, ERA5, the ECMWF operational analysis and MERRA-2). Long-duration, quasi-Lagrangian balloon observations in the equatorial and Antarctic lower stratosphere are used as a reference for the atmospheric spectrum and are compared to synthetic balloon observations along trajectories calculated using the wind and temperature fields of the reanalyses. Overall, the reanalyses represent realistic features of the spectrum, notably the spectral gap between planetary and gravity waves and a peak in horizontal kinetic energy associated with inertial waves near the Coriolis frequency f in the polar region. In the tropics, they represent the slope of the spectrum at low frequency. However, the variability is generally underestimated even in the low-frequency portion of the spectrum. In particular, the near-inertial peak, although present in the reanalyses, has a reduced magnitude compared to balloon observations. We compare the observed and modeled variabilities of temperature, zonal momentum flux and vertical wind speed, which are related to low-, mid- and high-frequency waves, respectively. The probability density function (PDF) distributions have similar shapes but show increasing disagreement with increasing intrinsic frequency. Since at those altitudes they are mainly caused by gravity waves, we also compare the geographic distribution of vertical wind fluctuations in the different products, which emphasizes the increase of both GW variance and intermittency with horizontal resolution. Finally, we quantify the fraction of resolved variability and its dependency on model resolution for the different variables. In all (re)analysis products, a significant part of the variability is still missing, especially at high frequencies, and should hence be parameterized. Among the two polar balloon datasets used, one was broadcast on the Global Telecommunication System for assimilation in NWP models, while the other consists of independent observations (unassimilated in the reanalyses). Comparing the Lagrangian spectra between the two campaigns shows that the (re)analyses are largely influenced by balloon data assimilation, which especially enhances the variance at low GW frequency.
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Jubair, Qahtan, and Farqad Hadi. "Development of 1D-Synthetic Geomechanical Well Logs for Applications Related to Reservoir Geomechanics in Buzurgan Oil Field." Iraqi Geological Journal 54, no. 2F (December 31, 2021): 74–88. http://dx.doi.org/10.46717/igj.54.2f.7ms-2021-12-24.
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Knowledge of the distribution of the rock mechanical properties along the depth of the wells is an important task for many applications related to reservoir geomechanics. Such these applications are wellbore stability analysis, hydraulic fracturing, reservoir compaction and subsidence, sand production, and fault reactivation. A major challenge with determining the rock mechanical properties is that they are not directly measured at the wellbore. They can be only sampled at well location using rock testing. Furthermore, the core analysis provides discrete data measurements for specific depth as well as it is often available only for a few wells in a field of interest. This study presents a methodology to generate synthetic-geomechanical well logs for the production section of the Buzurgan oil field, located in the south of Iraq, using an artificial neural network. An issue with the area of study is that shear wave velocities and pore pressure measurements in some wells are missing or incomplete possibly for cost and time-saving purposes. The unavailability of these data can potentially create inaccuracies in reservoir characterization n and production management. To overcome these challenges, this study presents two developed models for estimating the shear wave velocity and pore pressure using ANN techniques. The input parameters are conventional well logs including compressional wave, bulk density, and gamma-ray. Also, this study presents a construction of 1-D mechanical earth model for the production section of Buzurgan oil field which can be used for optimizing the selected mud weights with less wellbore problems (less nonproductive time. The results showed that artificial neural network is a powerful tool in determining the shear wave velocity and formation pore pressure using conventional well logs. The constructed 1D MEM revealed a high matching between the predicted wellbore instabilities and the actual wellbore failures that were observed by the caliper log. The majority of borehole enlargements can be attributed to the formation shear failures due to an inadequate selection of mud weights while drilling. Hence, this study presents optimum mud weights (1.3 to 1.35 g/cc) that can be used to drill new wells in the Buzurgan oil field with less expected drilling problems.
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Wang, Xiangyu Ivy, Xutao Zheng, Shuo Xiao, Jun Yang, Zi-Ke Liu, Yu-Han Yang, Jin-Hang Zou, et al. "GRB 210121A: A Typical Fireball Burst Detected by Two Small Missions." Astrophysical Journal 922, no. 2 (December 1, 2021): 237. http://dx.doi.org/10.3847/1538-4357/ac29bd.
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Abstract The Chinese CubeSat Mission, Gamma Ray Integrated Detectors (GRID), recently detected its first gamma-ray burst, GRB 210121A, which was jointly observed by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM). This burst is confirmed by several other missions, including Fermi and Insight-HXMT. We combined multimission observational data and performed a comprehensive analysis of the burst’s temporal and spectral properties. Our results show that the burst is relatively special in its high peak energy, thermal-like low-energy indices, and large fluence. By putting it to the E p –E γ,iso relation diagram with assumed distance, we found that this burst can be constrained at the redshift range of [0.3, 3.0]. The thermal spectral component is also confirmed by the direct fit of the physical models to the observed spectra. Interestingly, the physical photosphere model also constrained a redshift of z ∼ 0.3 for this burst, which helps us to identify a host galaxy candidate at such a distance within the location error box. Assuming that the host galaxy is real, we found that the burst can be best explained by the photosphere emission of a typical fireball with an initial radius of r 0 ∼ 3.2 × 107 cm.
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Stadtfeld, Christoph, Tom A. B. Snijders, Christian Steglich, and Marijtje van Duijn. "Statistical Power in Longitudinal Network Studies." Sociological Methods & Research 49, no. 4 (May 1, 2018): 1103–32. http://dx.doi.org/10.1177/0049124118769113.
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Longitudinal social network studies can easily suffer from insufficient statistical power. Studies that simultaneously investigate change of network ties and change of nodal attributes (selection and influence studies) are particularly at risk because the number of nodal observations is typically much lower than the number of observed tie variables. This article presents a simulation-based procedure to evaluate statistical power of longitudinal social network studies in which stochastic actor-oriented models are to be applied. Two detailed case studies illustrate how statistical power is strongly affected by network size, number of data collection waves, effect sizes, missing data, and participant turnover. These issues should thus be explored in the design phase of longitudinal social network studies.
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Gottfried, Michael A. "The Influence of Tardy Classmates on Students’ Socio-Emotional Outcomes." Teachers College Record: The Voice of Scholarship in Education 116, no. 3 (March 2014): 1–35. http://dx.doi.org/10.1177/016146811411600305.
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Background/Context Researchers, policymakers, and practitioners undoubtedly concur that missing school deteriorates student outcomes. And yet, in evaluating the deleterious effects of missing in-school time, empirical research has almost exclusively focused on absences, and the scant amount of empirical literature on tardiness has focused on academic achievement. Hence, this study contributes novel insight in two capacities: focusing on the effects of tardy classmates and focusing on socio-emotional outcomes. Purpose The purpose of this study is to determine the effects of peer-level tardiness on individual-level socio-emotional outcomes utilizing nationally representative, longitudinal data. Population/Participants/Subjects The data are sourced from the Early Childhood Longitudinal Study—Kindergarten Class (ECLS-K), which is a nationally representative sample of students, teachers, and schools. Information was first collected from kindergartners (as well as parents, teachers, and school administrators) from U.S. kindergarten programs in the 1998–1999 school year. This study utilizes data collected at spring of kindergarten, first grade, and third grade. Across all three waves of data, there were a total of N=21,765 student observations. Research Design This study combines secondary data analyses and quasi-experimental methods. There are five dependent socio-emotional variables utilized throughout this study, delineated into problem behaviors and social skills. Problem behaviors include two scales: (a) externalizing problem behaviors and (b) internalizing problem behaviors. Social skills include three scales: (a) level of self-control, (b) approaches to learning, and (c) interpersonal skills. This study begins with a baseline, linear regression model. To address issues pertaining to omitted variable bias, this study employs multilevel fixed effects modeling. Findings The coefficients on classroom tardies indicated statistically significant relationships between having a higher daily average number of classmate tardies and socio-emotional development. Students whose classmates are, on average, tardy more frequently have higher frequencies of problem behaviors and lower levels of social skills. The effects remain significant even after accounting for multiple omitted variable biases. Conclusions/Recommendations In addition to the previously well-established negative effects of missing school via absences, tardiness also diminishes student outcomes. Hence, the findings in this study—which brought to the surface new ways by which classmates’ actions can influence other students’ outcomes—would support the continuation of those school practices that successfully reduce multiple channels of missing school. Particularly high rates of peer tardies in addition to high rates of peer absences have both now been established in the research literature as detrimental to individual and classmate outcomes.
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Kothes, R., W. Reich, S. Safi-Harb, B. Guest, P. Reich, and E. Fürst. "A radio continuum and polarization study of the pulsar wind nebula CTB 87 (G74.9+1.2)." Monthly Notices of the Royal Astronomical Society 496, no. 1 (June 11, 2020): 723–38. http://dx.doi.org/10.1093/mnras/staa1573.
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ABSTRACT We present radio continuum and linear polarization observations of the pulsar wind nebula (PWN) CTB 87 (G74.9+1.2) with the Effelsberg 100-m Radio Telescope between 4.75 and 32 GHz. An analysis of these new data including archived low-frequency observations at 1420 and 408 MHz from the Canadian Galactic Plane Survey shows that CTB 87 consists of two distinct emission components: a compact kidney-shaped component, 14 × 8.5 pc2 (7.8 × 4.8 arcmin2) in size and a larger diffuse, spherical, and centrally peaked component of about 30 pc (17 arcmin) in diameter. The kidney-shaped component with a much steeper radio continuum spectrum is highly linearly polarized and likely represents a relic PWN. The diffuse component represents the undisturbed part of the PWN expanding inside a cavity or stellar wind bubble. The previously reported spectral break above 10 GHz is likely the result of missing large-scale emission and insufficient sensitivity of the high-frequency radio continuum observations. The simulation of the system’s evolution yields an age of about 18 000 yr as the result of a Type II supernova explosion with ejecta mass of about 12 M⊙ and explosion energy of about 7 × 1050 erg. We also found evidence for a radio shell in our polarization data that represents the blast wave that entered the molecular cloud complex at a radius of about 13 pc.
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Bartlett, Rodney. "Using the discovery of fundamental variables by artificial intelligence to unite general relativity and quantum mechanics." Aeronautics and Aerospace Open Access Journal 6, no. 3 (August 24, 2022): 111–16. http://dx.doi.org/10.15406/aaoaj.2022.06.00149.
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Article includes “Linking radioactive dating to origin of the universe” or “How dinosaurs committed scientific heresy & exterminated the Big Bang” Vector-tensor-scalar geometry’s important insights into 1) Cancer, 2) The origin of the moon In a newsletter discussing “Automated discovery of fundamental variables hidden in experimental data” (Chen, B., Huang, K., Raghupathi, S. et al. Automated discovery of fundamental variables hidden in experimental data. Nat Comput Sci 2, 433–442 (2022). Cosmos Magazine attributed the following statement to co-author Qiang Du, “What other laws are we missing simply because we don’t have the variables?” According to Cosmos, another co-author (Hod Lipson) argues that scientists may be misinterpreting or failing to understand many phenomena simply because they don’t have a good set of variables. All of this reminds me of the Hidden Variables associated with Albert Einstein’s doubts about quantum mechanics. I’ve been thinking about hidden variables for perhaps twenty or more years and it seems that their combination with the Mobius strip, figure-8 Klein bottle, base 2 mathematics, vector-tensor-scalar geometry, and Wick rotation might unite quantum mechanics and relativity. The union would result in explanation of particles existing in two or more places at once being due to our frame of reference. It would also explain wave-particle duality and, on a universal scale, why there was no Big Bang. The section on vector-tensor-scalar geometry is very important since it provides insights into 1) cancer, and 2) the origin of the moon. The yet-to-be-discovered underlying physics of the wave function proposed in this comment predicts exactness in outcomes, not probability or randomness. Quantum mechanics says particles can, according to our frame of reference, be in two or more places at once. This frame of reference is necessarily restricted to our present understanding of quantum mechanics which Albert Einstein and his colleagues claimed to be incomplete. Hidden Variables are presently hypothetical factors based on the belief that the theory of quantum mechanics is incomplete. Their identification would lead to exact predictions, not just probabilities, for the outcomes of measurements. Albert Einstein is the most famous proponent of hidden variables. Their existence would vindicate his belief that quantum mechanics is lacking something. It’s proposed here that electronics’ binary digits (1’s and 0’s) are those hidden variables. Despite Bell’s theorem and the more recent Pusey–Barrett–Rudolph theorem, hidden variables can be a valid theory since the following boxed explanation of unification of all time periods allows the existence of both “retarded” waves going forwards in time and the disfavoured “advanced” waves travelling back in time and this permits quantum entanglement of every form of mass if, as shown, gravitational waves interacting with electromagnetic waves is responsible for production of mass. The misperception that the universe is expanding is accounted for by retarded/advanced shift.
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Kesari Singh and Nisha Singh. "A Qualitative Analysis of Healthcare Students’ Perceptions Towards Online Learning due to the COVID-19 Pandemic." International Healthcare Research Journal 5, no. 5 (August 28, 2021): OR1—OR4. http://dx.doi.org/10.26440/ihrj/0505.08427.
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INTRODUCTION: While online learning has the ability to bring students and teachers together in the Distance Education (DE) mode, it is not feasible in the healthcare based professions. AIM: To analyze healthcare students’ perceptions towards online learning due to the COVID-19 pandemic. MATERIALS AND METHOD: This qualitative, focus group-based study was done on the three focus groups consisting of 15 students each: medical, dental and allied sciences. Data were collected using observations from the recordings of the scheduled online interview which was approximately 30-minutes in length and the investigator asked questions from the pre-validated interview guide consisting of seven questions. Data was analyzed using the constant comparative method, which was then consequently categorized into two major areas: positive experiences and negative experiences. Positive experiences included: time flexibility, convenience, ease of connection and ease of learning; while negative experiences included instructor’s inexperience and a lack of interaction, self-motivation, isolation and missing out on practical learning. RESULTS: While responses of the positive experience ranged from “I have the flexibility to wake up few minutes before the lecture and directly log on for the lecture” to “Even during the closure of schools/ classes, I need not worry about lagging behind in my studies”; the negative experiences included statements like “the inexperience of the instructor in handling the teaching software led to difficulties and interruption in learning” and “I am a great loss due to missing patient work!! How am I going to become a good doctor if I don’t practise on patients under supervision of my staff”. CONCLUSION: While students are slowly adapting themselves to online based learning, those belonging to the healthcare sector are missing out on their practical classes which has the potential to hamper the quality of care being provided by them as future professionals.
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Widyaningsih, Vitri, Alimah Premanawasti, Anis Sofia, Nada Syifa, Amelya Augusthina, Yusuf Mashuri, Ratih Puspita Febrinasari, et al. "Sociodemographic Differences in Multimorbidity: A Closer Look from Indonesian Family and Life Survey." BIO Web of Conferences 54 (2022): 00010. http://dx.doi.org/10.1051/bioconf/20225400010.
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The prevalence of multimorbidity, the coexistence of two or more chronic diseases, is expected to increase, including in Indonesia. This phenomenon is associated with increased life expectancy and incidence of non-communicable diseases. Therefore, this study assesses the burden of multimorbidity in Indonesia by sociodemographic factors. The researchers analyzed cross-sectional data from the latest wave of IFLS conducted in 2014, the IFLS wave 5. The researchers included individuals aged 15 and above with blood pressure measurements (n= 32.256) from 13,536 households. Meanwhile, the researchers excluded individuals with missing data on BMI (183 individuals) or who had biologically implausible or extreme values (n=6). The analyses were then conducted on 32,067 individuals. The analyses comprised the ten most common self-reported chronic diseases diagnosis in IFLS-5. The findings revealed that the prevalence of self-reported multimorbidity in Indonesia was relatively high, at 9.32% (n= 2.989), with the highest proportion of multimorbidity reported among the elderly. Approximately 2.76% of the respondents (n- 885) reported having three or more chronic diseases. The most common combinations were hypertension and digestive problem (2.15%, n= 689), followed by hypertension and arthritis (1.79%, n= 574), and hypertension and high cholesterol (1.68%, n= 539). When stratified by sociodemographic factors, the researchers found a higher proportion of multimorbidity among females (11.01%, n= 3,530) compared to males (7.41%, n= 2.376), elderly (21.54%, n= 3.530) compared to younger adults, and previous smokers (20.90%, n= 6.072). People who were obese and overweight also reported a higher prevalence of multimorbidity (13.73%, n= 4.403 and 9.3%, n= 2.998, respectively). In addition, those living in urban areas had a higher proportion of multimorbidity (10.33%, n= 3.313) compared to rural areas (7.2%, n= 2.527). In conclusion, this study uncovered a relatively high prevalence of multimorbidity. People living in urban areas were overweight/obese and those who had low SES had a higher proportion of multimorbidity. With the nature of self-reported data and previously reported underdiagnosis of chronic diseases, screening to examine multimorbidity is needed.
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Pennoni, Fulvia, and Miki Nakai. "A latent class analysis towards stability and changes in breadwinning patterns among coupled households." Dependence Modeling 7, no. 1 (July 26, 2019): 234–46. http://dx.doi.org/10.1515/demo-2019-0012.
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AbstractA latent class model is proposed to examine couples’ breadwinning typologies and explain the wage differentials according to the socio-demographic characteristics of the society with data collected through surveys. We derive an ordinal variable indicating the couple’s income provision-role type and suppose the existence of an underlying discrete latent variable to model the effect of covariates. We use a two-step maximum likelihood inference conducted to account for concomitant variables, informative sampling scheme and missing responses. The weighted log-likelihood is maximised through the Expectation-Maximization algorithm and information criteria are used to develop the model selection. Predictions are made on the basis of the maximum posterior probabilities. Disposing of data collected in Japan over thirty years we compare couples’ breadwinning patterns across time. We provide some evidence of the gender wage-gap and we show that it can be attributed to the fact that, especially in Japan, duties and responsibilities for the child care are supported exclusively by women.
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Haim, Mario, and Angela Nienierza. "Computational observation : Challenges and opportunities of automated observation within algorithmically curated media environments using a browser plug-in." Computational Communication Research 1, no. 1 (October 1, 2019): 79–102. http://dx.doi.org/10.5117/ccr2019.1.004.haim.
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Abstract A lot of modern media use is guided by algorithmic curation, a phenomenon that is in desperate need of empirical observation, but for which adequate methodological tools are largely missing. To fill this gap, computational observation offers a novel approach—the unobtrusive and automated collection of information encountered within algorithmically curated media environments by means of a browser plug-in. In contrast to prior methodological approaches, browser plug-ins allow for reliable capture and repetitive analysis of both content and context at the point of the actual user encounter. After discussing the technological, ethical, and practical considerations relevant to this automated solution, we present our open-source browser plug-in as an element in an adequate multi-method design, along with potential links to panel surveys and content analysis. Ultimately, we present a proof-of-concept study in the realm of news exposure on Facebook; we successfully deployed the plug-in to Chrome and Firefox, and we combined the computational observation with a two-wave panel survey. Although this study suffered from severe recruitment difficulties, the results indicate that the methodological setup is reliable and ready to implement for data collection within a variety of studies on media use and media effects.
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Lebedev, Daniil. "Using GPS-Paradata to Control the Data Collection Process: Review of Existing Methods and Analysis of GPS-Paradata Quality." Sociological Journal 28, no. 4 (December 28, 2022): 8–33. http://dx.doi.org/10.19181/socjour.2022.28.4.9313.
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The use of face-to-face interviews is still a very common data collection method in social sciences. The danger associated with the use of such data collection methods is a reduction in the resulting survey data’s quality due to interviewers’ fabrications or falsifications, which in turn has led to the emergence of a large set of methods for controlling the data collection process, the focus of which is limited and bypasses the behavioral characteristics of interviewers. In this context, paradata and GPS-paradata are an important new tool for use in the process of quality control of collected data or as part of a methodological audit, allowing not only to potentially identify and prevent falsification or fabrication by interviewers, but also to assess the correctness of methodological instructions. This article provides an overview of the available and practiced methods for using GPS-paradata in two main strategies (data point analysis and interviewer path analysis): geofencing, strand length, curbstoning, connecting interviews’ locations and interviewer path analysis. The possibilities of using such control methods depend on the sample design and on the methodological features of the surveys in general. However, the use of GPS-paradata to control the data collection process is not in itself a surefire method for detecting interviewers’ fabrications or falsifications, as it may be subject to technical inaccuracies or unintentional interviewer errors. It is a useful additional method aimed at identifying “suspicious” interviews which require the use of more resource-intensive methods of control (for example, repeated contact). In addition, the article presents an analysis of the quality of acquired GPS-paradata on the example of 26th wave of the RLMS-HSE, based on analyzing missing data and quality of measurements (HDOP). The results show that the quality of GPS-paradata can be related both to the region where the interview is conducted and to the characteristics of the interviewers.