Journal articles on the topic 'Approximate magnitudes'
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1
Sullivan, Jessica, and David Barner. "How are number words mapped to approximate magnitudes?" Quarterly Journal of Experimental Psychology 66, no. 2 (February 2013): 389–402. http://dx.doi.org/10.1080/17470218.2012.715655.
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Birol, İnanç, and Avadis Hacinliyan. "Signs and approximate magnitudes of Lyapunov exponents in continuous time dynamical systems." Journal of Mathematical Physics 38, no. 9 (September 1997): 4594–605. http://dx.doi.org/10.1063/1.532109.
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Obersteiner, Andreas, and Veronika Hofreiter. "Do we have a sense for irrational numbers?" Journal of Numerical Cognition 2, no. 3 (February 10, 2017): 170–89. http://dx.doi.org/10.5964/jnc.v2i3.43.
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Number sense requires, at least, an ability to assess magnitude information represented by number symbols. Most educated adults are able to assess magnitude information of rational numbers fairly quickly, including whole numbers and fractions. It is to date unclear whether educated adults without training are able to assess magnitudes of irrational numbers, such as the cube root of 41. In a computerized experiment, we asked mathematically skilled adults to repeatedly choose the larger of two irrational numbers as quickly as possible. Participants were highly accurate on problems in which reasoning about the exact or approximate value of the irrational numbers’ whole number components (e.g., 3 and 41 in the cube root of 41) yielded the correct response. However, they performed at random chance level when these strategies were invalid and the problem required reasoning about the irrational number magnitudes as a whole. Response times suggested that participants hardly even tried to assess magnitudes of the irrational numbers as a whole, and if they did, were largely unsuccessful. We conclude that even mathematically skilled adults struggle with quickly assessing magnitudes of irrational numbers in their symbolic notation. Without practice, number sense seems to be restricted to rational numbers.
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Guo, Yueming, Philip Nakashima, and Joanne Etheridge. "Structure factor measurement by 3-beam convergent beam electron diffraction." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1623. http://dx.doi.org/10.1107/s2053273314083764.
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It has been shown mathematically that both the magnitudes and 3-phase invariants of the structure factors of a centrosymmetric crystal can be expressed explicitly in terms of the distances to specific features in the 3-beam convergent beam electron diffraction (CBED) pattern [1].This theoretical inversion can be implemented experimentally, enabling direct observations of 3-phase invariants and the approximate measurement of structure factor magnitudes. This method then enables a different approach to crystal structure determination, which is based on the observation of phases, rather than the measurement of amplitudes. It has been shown that by inspection of just a few phases using 3-beam CBED patterns, centrosymmetric crystal structures can be determined directly to picometre precision without the need to measure magnitudes [2]. Here, we will explore a different approach for measuring structure factor magnitudes from 3-beam CBED patterns. It has been demonstrated that the relative structure factor magnitudes can be determined directly from the ratio of the intensity distributions along specific lines within the CBED discs [3]. We will investigate the potential of using this approach for the relatively fast measurement of approximate structure factor magnitudes from nano-scale volumes of crystals.
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Ebaid, Abdelhalim, Weam Alharbi, Mona D. Aljoufi, and Essam R. El-Zahar. "The Exact Solution of the Falling Body Problem in Three-Dimensions: Comparative Study." Mathematics 8, no. 10 (October 8, 2020): 1726. http://dx.doi.org/10.3390/math8101726.
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Very recently, the system of differential equations governing the three-dimensional falling body problem (TDFBP) has been approximately solved. The previously obtained approximate solution was based on the fact that the Earth’s rotation (ER) is quite slow and hence all high order terms of ω in addition to the magnitude ω2R were neglected, where ω is the angular velocity and R is the radius of Earth. However, it is shown in this paper that the ignorance of such magnitudes leads, in many cases, to significant errors in the estimated falling time and other physical quantities. The current results are based on obtaining the exact solutions of the full TDFBP-system and performing several comparisons with the approximate ones in the relevant literature. The obtained results are of great interest and importance, especially for other planets in the Solar System or exterior planets, in which ω and/or ω2R are of considerable amounts and hence cannot be ignored. Therefore, the present analysis is valid in analyzing the TDFBP near to the surface of any spherical celestial body.
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Ganor-Stern, Dana. "Can Dyscalculics Estimate the Results of Arithmetic Problems?" Journal of Learning Disabilities 50, no. 1 (August 4, 2016): 23–33. http://dx.doi.org/10.1177/0022219415587785.
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The present study is the first to examine the computation estimation skills of dyscalculics versus controls using the estimation comparison task. In this task, participants judged whether an estimated answer to a multidigit multiplication problem was larger or smaller than a given reference number. While dyscalculics were less accurate than controls, their performance was well above chance level. The performance of controls but not of those with developmental dyscalculia (DD) improved consistently for smaller problem sizes. The performance of both groups was superior when the reference number was smaller (vs. larger) than the exact answer and when it was far (vs. close) from it, both of which are considered to be the markers of the approximate number system (ANS). Strategy analysis distinguished between an approximated calculation strategy and a sense of magnitude strategy, which does not involve any calculation but relies entirely on the ANS. Dyscalculics used the latter more often than controls. The present results suggest that there is little, if any, impairment in the ANS of adults with DD and that their main deficiency is with performing operations on magnitudes rather than with the representations of the magnitudes themselves.
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Stock, J., and C. Abad. "Recovery of the Astrographic Catalogue." Symposium - International Astronomical Union 133 (1988): 171–76. http://dx.doi.org/10.1017/s0074180900139580.
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An almost fully automatic scheme has been developed which produces final positions in the system determined by the reference catalogue, cross identifications, and approximate magnitudes in a standard system. A plate-overlap method is used which permits inclusion of higher order terms either plate by plate or common to a subset of plates. Magnitude dependent errors are also included. The system has already been applied to more than 500 plates, most of them of the Paris zone, with smaller sets of the Oxford, Potsdam, and Helsingfors zones. The Paris zone yields consistent higher order and magnitude terms over the entire set analyzed so far.
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Kuhn, Jörg-Tobias. "Developmental Dyscalculia." Zeitschrift für Psychologie 223, no. 2 (July 10, 2015): 69–82. http://dx.doi.org/10.1027/2151-2604/a000205.
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Developmental dyscalculia (DD) is a specific learning disorder that affects the acquisition of arithmetic skills and number processing in children. A high comorbidity between DD and other neurodevelopmental disorders (e.g., dyslexia, attention-deficit/hyperactivity disorder [ADHD]) as well as substantial heterogeneity in cognitive profiles have been reported. Current studies indicate that DD is persistent, has a genetic component, and is related to functional and structural alterations of brain areas involved in magnitude representation. Recent neuronal and behavioral evidence is presented, showing that DD entails (a) impairments in two preverbal core systems of number, an approximate system for estimating larger magnitudes and an exact system for representing small magnitudes, (b) deficits in symbolic number processing, (c) aberrant and nonadaptive neuronal activation in basic magnitude processing and calculation, (d) dysfunctional arithmetic fact retrieval and persistent use of counting strategies in calculation, and (e) deficits in visuospatial working memory and the central executive. Finally, open research questions, including the role of domain-general cognitive resources in DD, causes and developmental consequences of comorbidity, as well as design and evaluation of interventions for DD, are briefly discussed.
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Hyde, Daniel C., and Justin N. Wood. "Spatial Attention Determines the Nature of Nonverbal Number Representation." Journal of Cognitive Neuroscience 23, no. 9 (September 2011): 2336–51. http://dx.doi.org/10.1162/jocn.2010.21581.
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Coordinated studies of adults, infants, and nonhuman animals provide evidence for two systems of nonverbal number representation: a “parallel individuation” system that represents individual items and a “numerical magnitude” system that represents the approximate cardinal value of a group. However, there is considerable debate about the nature and functions of these systems, due largely to the fact that some studies show a dissociation between small (1–3) and large (>3) number representation, whereas others do not. Using event-related potentials, we show that it is possible to determine which system will represent the numerical value of a small number set (1–3 items) by manipulating spatial attention. Specifically, when attention can select individual objects, an early brain response (N1) scales with the cardinal value of the display, the signature of parallel individuation. In contrast, when attention cannot select individual objects or is occupied by another task, a later brain response (P2p) scales with ratio, the signature of the approximate numerical magnitude system. These results provide neural evidence that small numbers can be represented as approximate numerical magnitudes. Further, they empirically demonstrate the importance of early attentional processes to number representation by showing that the way in which attention disperses across a scene determines which numerical system will deploy in a given context.
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Du, Qinghui, and Chaoli Wang. "Convergence Analysis of Semi-Implicit Euler Methods for Solving Stochastic Age-Dependent Capital System with Variable Delays and Random Jump Magnitudes." Mathematical Problems in Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/460530.
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We consider semi-implicit Euler methods for stochastic age-dependent capital system with variable delays and random jump magnitudes, and investigate the convergence of the numerical approximation. It is proved that the numerical approximate solutions converge to the analytical solutions in the mean-square sense under given conditions.
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BARNER, DAVID. "Language, procedures, and the non-perceptual origin of number word meanings." Journal of Child Language 44, no. 3 (April 5, 2017): 553–90. http://dx.doi.org/10.1017/s0305000917000058.
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AbstractPerceptual representations of objects and approximate magnitudes are often invoked as building blocks that children combine to acquire the positive integers. Systems of numerical perception are either assumed to contain the logical foundations of arithmetic innately, or to supply the basis for their induction. I propose an alternative to this framework, and argue that the integers are not learned from perceptual systems, but arise to explain perception. Using cross-linguistic and developmental data, I show that small (~1–4) and large (~5+) numbers arise both historically and in individual children via distinct mechanisms, constituting independent learning problems, neither of which begins with perceptual building blocks. Children first learn small numbers using the same logic that supports other linguistic number marking (e.g. singular/plural). Years later, they infer the logic of counting from the relations between large number words and their roles in blind counting procedures, only incidentally associating number words with approximate magnitudes.
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Wu, Shen-Chyun, C. Allin Cornell, and Steven R. Winterstein. "A hybrid recurrence model and its implication on seismic hazard results." Bulletin of the Seismological Society of America 85, no. 1 (February 1, 1995): 1–16. http://dx.doi.org/10.1785/bssa0850010001.
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Abstract To account for the effects of the characteristic earthquakes on an individual fault (segment), a renewal hybrid model is proposed for seismic hazard analysis and studied in depth. This model incorporates a renewal-time, characteristic-magnitude model for larger earthquakes with the conventional exponential-time, exponential-magnitude model for smaller earthquakes. Properties of important temporal and magnitude parameters are studied. The exact and the approximate (“first-event”) hazards estimated by this model are discussed. The approximate results are found sufficiently accurate for most engineering applications. These approximations can be obtained by making minor modifications to existing hazard analysis programs designed for traditional Poisson models. Hazard estimates of this model and other more complicated hybrid models, e.g., time- and slip-predictable models, are compared. For reasonable parameter values, the characteristic events are found to be the major contributor to seismic hazards in most cases, unless the source-site distance is very small. This effect is even stronger with a large elapsed time in a nonmemoryless interarrival time distribution. Based on previous findings of small values of the coefficients of variation in time and low correlations between the interarrival times and magnitudes among characteristic earthquakes, the proposed renewal hybrid model will produce hazard estimates close to those of more complicated non-Poissonian models.
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Van Rinsveld, Amandine, Mathieu Guillaume, Peter J. Kohler, Christine Schiltz, Wim Gevers, and Alain Content. "The neural signature of numerosity by separating numerical and continuous magnitude extraction in visual cortex with frequency-tagged EEG." Proceedings of the National Academy of Sciences 117, no. 11 (March 2, 2020): 5726–32. http://dx.doi.org/10.1073/pnas.1917849117.
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The ability to handle approximate quantities, or number sense, has been recurrently linked to mathematical skills, although the nature of the mechanism allowing to extract numerical information (i.e., numerosity) from environmental stimuli is still debated. A set of objects is indeed not only characterized by its numerosity but also by other features, such as the summed area occupied by the elements, which often covary with numerosity. These intrinsic relations between numerosity and nonnumerical magnitudes led some authors to argue that numerosity is not independently processed but extracted through a weighting of continuous magnitudes. This view cannot be properly tested through classic behavioral and neuroimaging approaches due to these intrinsic correlations. The current study used a frequency-tagging EEG approach to separately measure responses to numerosity as well as to continuous magnitudes. We recorded occipital responses to numerosity, total area, and convex hull changes but not to density and dot size. We additionally applied a model predicting primary visual cortex responses to the set of stimuli. The model output was closely aligned with our electrophysiological data, since it predicted discrimination only for numerosity, total area, and convex hull. Our findings thus demonstrate that numerosity can be independently processed at an early stage in the visual cortex, even when completely isolated from other magnitude changes. The similar implicit discrimination for numerosity as for some continuous magnitudes, which correspond to basic visual percepts, shows that both can be extracted independently, hence substantiating the nature of numerosity as a primary feature of the visual scene.
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Li, Zhigang, Jinyu Yu, and Q. H. Wu. "Approximate Linear Power Flow Using Logarithmic Transform of Voltage Magnitudes With Reactive Power and Transmission Loss Consideration." IEEE Transactions on Power Systems 33, no. 4 (July 2018): 4593–603. http://dx.doi.org/10.1109/tpwrs.2017.2776253.
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Lim, Teik-Cheng. "Adjustable positive and negative hygrothermal expansion metamaterial inspired by the Maltese cross." Royal Society Open Science 8, no. 8 (August 2021): 210593. http://dx.doi.org/10.1098/rsos.210593.
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A metamaterial that can manifest both positive and negative coefficients of moisture and thermal expansion is presented herein, based on inspiration from the Maltese cross. Each unit of the metamaterial consists of a pair of equal-armed crosses pin-joined at their junctions to permit rotation, but elastically restrained by a bimaterial spiral spring, and four pairs of hinge rods to translate the relative rotational motion of the pair of equal-armed crosses into translational motion of the connecting rods. The effective coefficients of moisture and thermal expansion models were developed for small and large changes in the hygrothermal conditions using infinitesimal (approximate) and finite (exact) motion analyses, respectively, with the former giving constant effective coefficients with respect to environmental changes. Results indicate that the approximate method underestimates the magnitude of both the effective expansion coefficients under cooling and drying but overestimates magnitudes of both coefficients during heating and moistening, and that the change in both expansion coefficients is more drastic during cooling and drying than during heating and moistening. In addition to providing another micro-lattice geometry for effecting expansion coefficients of either signs, this metamaterial exhibits auxetic property.
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Bozorgnia, Yousef, Mahmoud M. Hachem, and Kenneth W. Campbell. "Ground Motion Prediction Equation (“Attenuation Relationship”) for Inelastic Response Spectra." Earthquake Spectra 26, no. 1 (February 2010): 1–23. http://dx.doi.org/10.1193/1.3281182.
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This paper presents the process and fundamental results of a comprehensive ground motion prediction equation (GMPE, or “attenuation” relationship) developed for inelastic response spectra. We used over 3,100 horizontal ground motions recorded in 64 earthquakes with moment magnitudes ranging from 4.3–7.9 and rupture distances ranging from 0.1–199 km. For each record, we computed inelastic spectra for ductility ranging from one (elastic response) to eight. Our GMPE correlates inelastic spectral ordinates to earthquake magnitude, site-to-source distance, fault mechanism, local soil properties, and basin effects. The developed GMPE is used in both deterministic and probabilistic hazard analyses to directly generate inelastic spectra. This is in contrast to developing “attenuation” relationships for elastic response spectra, carrying out a hazard analysis, and subsequently adopting approximate rules to derive inelastic response from elastic spectra.
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Lalith, Mulukala Sri, Patthi Sridhar, Ranjith Kumar Gatla, and Alladi Sathish Kumar. "Evaluation of Surge Voltages on the Overhead Lines due to Direct and Indirect Lightning Impulse." Journal Européen des Systèmes Automatisés 54, no. 5 (October 31, 2021): 751–62. http://dx.doi.org/10.18280/jesa.540510.
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This paper is devoted to describe how surge magnitudes are calculated and how do we use this data in order to determine the ageing of insulation on the transmission line poles so that we can replace the insulation in pre fault time, based on its condition. The main object of this report is to design algorithm of implementation of SCADA in the transmission line system to identify insulation ageing factor. In order to identify the magnitude of voltage due to direct lightning source, we have some formulae which provides the approximate value. For the magnitude value due to indirect lightning strokes, we use two methods namely RBF-FDTD method which uses artificial neural network function in order to study the detailed concept of coupling between field to transmission lines and the other method is the modelling of simulation system in which the coupling system approximations are taken. This paper also describes about the calculation of outage rate and its Geometrical analysis.
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Fan, Shuai, and Shouwen Fan. "Approximate Stiffness Modelling and Stiffness Defect Identification for a Heavy-load Parallel Manipulator." Robotica 37, no. 6 (February 18, 2019): 1120–42. http://dx.doi.org/10.1017/s0263574718001492.
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SummaryWhen using parallel manipulators as machine tools, their stiffness is an important factor in the quality of the produced products. This paper presents an overall approximate stiffness model for a heavy-load parallel manipulator, which considers the effects of actuator stiffness, joint clearance, joint contact deformation, and limb deformation. Based on the principle of virtual work and the introduced modified parameters, the proposed overall compliance matrix successfully takes four factors into a unified expression. To obtain the overall compliance matrix, the approximate stiffness models of the joint clearance, joint contact deformation, and limb deformation are given. In addition, by combining the statistical simulation including the random uncertainties and the proposed approximate stiffness models as the basis of the magnitudes for each random variable, an approach based on the expected trajectory and external load is also proposed for stiffness defect identification such that the estimation is more accurate and reliable. Finally, a numerical example of the 1PU+3UPS parallel manipulator and a discussion are presented to demonstrate the practicability of the proposed stiffness model and defect identification approach. After modifying the structure parameters of the defective components, the prototype experiences a significant stiffness improvement.
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Ju, Yuntao. "Discussion on “Approximate Linear Power Flow Using Logarithmic Transform of Voltage Magnitudes With Reactive Power and Transmission Loss Consideration”." IEEE Transactions on Power Systems 34, no. 5 (September 2019): 3984. http://dx.doi.org/10.1109/tpwrs.2019.2932509.
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Campos-García, J. C., M. E. Molinar-Tabares, C. Figueroa-Navarro, and L. Castro-Arce. "Approximate construction of new conservative physical magnitudes through the fractional derivative of polynomialtype functions: a particular case in semiconductors of type AlxGa1-xAs." Revista Mexicana de Física 66, no. 6 Nov-Dec (November 5, 2020): 874. http://dx.doi.org/10.31349/revmexfis.66.874.
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The fractional calculus has a very large diversification as it relates to applications from physical interpretations to experimental facts to modeling of new problems in the natural sciences. Within the framework of a recently published article, we obtained the fractional derivative of the variable concentration x (z), the effective mass of the electron dependent on the position m (z) and the potential energy V (z), produced by the confinement of the electron in a semiconductor of type AlxGa1-xAs, with which we can intuit a possible geometric and physical interpretation. As a consequence, it is proposed the existence of three physical and geometric conservative quantities approximate character, associated with each of these parameters of the semiconductor, which add to the many physical magnitudes that already exist in the literature within the context of fractional variation rates. Likewise, we find that the fractional derivatives of these magnitudes, apart from having a common critical point, manifest self-similar behavior, which could characterize them as a type of fractal associated with the type of semiconductor structures under study.
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Patwardhan, Avinash G., Kevin P. Meade, and Brian Lee. "A Frontal Plane Model of the Lumbar Spine Subjected to a Follower Load: Implications for the Role of Muscles." Journal of Biomechanical Engineering 123, no. 3 (December 21, 2000): 212–17. http://dx.doi.org/10.1115/1.1372699.
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Compression on the lumbar spine is 1000 N for standing and walking and is higher during lifting. Ex vivo experiments show it buckles under a vertical load of 80–100 N. Conversely, the whole lumbar spine can support physiologic compressive loads without large displacements when the load is applied along a follower path that approximates the tangent to the curve of the lumbar spine. This study utilized a two-dimensional beam–column model of the lumbar spine in the frontal plane under gravitational and active muscle loads to address the following question: Can trunk muscle activation cause the path of the internal force resultant to approximate the tangent to the spinal curve and allow the lumbar spine to support compressive loads of physiologic magnitudes? The study identified muscle activation patterns that maintained the lumbar spine model under compressive follower load, resulting in the minimization of internal shear forces and bending moments simultaneously at all lumbar levels. The internal force resultant was compressive, and the lumbar spine model, loaded in compression along the follower load path, supported compressive loads of physiologic magnitudes with minimal change in curvature in the frontal plane. Trunk muscles may coactivate to generate a follower load path and allow the ligamentous lumbar spine to support physiologic compressive loads.
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Alcorn, Sara R., Xian Chiong Zhou, Casey Bojechko, Rodrigo A. Rubo, Michael J. Chen, Karin Dieckmann, Ralph P. Ermoian, et al. "Low-Dose Image-Guided Pediatric CNS Radiation Therapy: Final Analysis From a Prospective Low-Dose Cone-Beam CT Protocol From a Multinational Pediatrics Consortium." Technology in Cancer Research & Treatment 19 (January 1, 2020): 153303382092065. http://dx.doi.org/10.1177/1533033820920650.
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Background: Lower-dose cone-beam computed tomography protocols for image-guided radiotherapy may permit target localization while minimizing radiation exposure. We prospectively evaluated a lower-dose cone-beam protocol for central nervous system image-guided radiotherapy across a multinational pediatrics consortium. Methods: Seven institutions prospectively employed a lower-dose cone-beam computed tomography central nervous system protocol (weighted average dose 0.7 mGy) for patients ≤21 years. Treatment table shifts between setup with surface lasers versus cone-beam computed tomography were used to approximate setup accuracy, and vector magnitudes for these shifts were calculated. Setup group mean, interpatient, interinstitution, and random error were estimated, and clinical factors were compared by mixed linear modeling. Results: Among 96 patients, with 2179 pretreatment cone-beam computed tomography acquisitions, median age was 9 years (1-20). Setup parameters were 3.13, 3.02, 1.64, and 1.48 mm for vector magnitude group mean, interpatient, interinstitution, and random error, respectively. On multivariable analysis, there were no significant differences in mean vector magnitude by age, gender, performance status, target location, extent of resection, chemotherapy, or steroid or anesthesia use. Providers rated >99% of images as adequate or better for target localization. Conclusions: A lower-dose cone-beam computed tomography protocol demonstrated table shift vector magnitude that approximate clinical target volume/planning target volume expansions used in central nervous system radiotherapy. There were no significant clinical predictors of setup accuracy identified, supporting use of this lower-dose cone-beam computed tomography protocol across a diverse pediatric population with brain tumors.
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Luan, X., L. Liu, W. Wan, J. Lei, and T. Yu. "A climatology of the F-layer equivalent winds derived from ionosonde measurements over two decades along the 120°-150°E sector." Annales Geophysicae 22, no. 8 (September 7, 2004): 2785–96. http://dx.doi.org/10.5194/angeo-22-2785-2004.
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Abstract. The vertical equivalent winds (VEWs) at the F-layer are analyzed along the 120°-150°E longitude sector with an emphasis on their latitudinal dependence. The VEWs are derived from the monthly median data of fourteen ionosonde stations over two decades. The results show that the VEWs have considerable dependences on the magnetic latitude with an approximate symmetry about the magnetic equator. They are mostly controlled by the electric field drifts in the magnetic equatorial region, and shift to be mostly contributed by neutral winds at mid-latitudes. The relative contribution of the two dynamic factors is regulated by the magnetic dip in addition to their own magnitudes. The VEWs generally have opposite directions and different magnitudes between lower and higher latitudes. At solar minimum, the magnitudes of VEWs are only between -20 and 20m/s at lower latitudes, while at higher latitudes they tend to increase with latitudes, typically having magnitudes between 20-40m/s. At solar maximum, the VEWs are reduced by about 10-20m/s in magnitudes during some local times at higher latitudes. A tidal analysis reveals that the relative importance of major tidal components is also different between lower and higher latitudes. The VEWs also depend on local time, season and solar activity. At higher latitudes, the nighttime VEWs have larger magnitude during post-midnight hours and so do the daytime ones before midday. The VEWs tend to have an inverse relationship with solar activity not only at night, but also by day, which is different from the meridional winds predicted by the HWM93 model. The latitudinal dependence of VEWs has two prevailing trends: one is a maximum at the highest latitudes (as far as the latitudes concerned in the present work); the other is a mid-latitude maximum. These two latitudinal trends are mostly dependent on season, while they depend relatively weakly on local time and solar activity. The latitudinal gradients of VEWs also show a tendency of a mid-latitude maximum, except that there are much stronger latitudinal gradients at southern higher mid-latitudes in some seasons. The gradients during daytime are much smaller at solar maximum than minimum, whereas they are generally comparable at night under both solar activity levels.
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Liu, Renqiang, and Yanyan Fu. "Verification of an Approximate Thermodynamic Equation with Application to Study on Arctic Stratospheric Temperature Changes." Journal of the Atmospheric Sciences 76, no. 1 (December 17, 2018): 3–9. http://dx.doi.org/10.1175/jas-d-18-0109.1.
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Abstract Temperature changes in the Arctic lower stratosphere on both short- and long-term time scales are critical for changing the magnitude of ozone losses in the Arctic vortex. In this paper, an approximate month-to-month temperature change equation is constructed and extended to a new form for decade-to-decade changes. Then we provide a verification of these equations and show an example of an application for partitioning between the dynamical and radiative contributions to the Arctic lower-stratospheric temperature decadal changes, as well as the trends, using the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) data during the period of 1980–99. At 100 hPa, the month-to-month Arctic temperature increment is a small term compared to the dynamical heating and diabatic heating, which are largely canceling terms with maximum magnitudes in November–April and October–March, respectively. However, it is not the case for their decadal changes and the decadal change of the Arctic current-month temperature compared to those of the regressed dynamical heating and radiative heating, where the current-month decadal changes and the corresponding trends are approached except in March and a rough agreement exists between these trends and those reported in other studies. The dynamical plus diabatic heating term and the temperature increment, as well as their decadal changes, are roughly balanced during the annual oscillation. However, some departures exist in both cases because of the large deviations or uncertainties of relevant terms and also probably due to the quasigeostrophic approximation and the eddy heat flux approximation of the dynamical heating, and a restricted condition of the eddy heat flux approximation is given at the end.
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Almeida, Manoel C. "Neurociência, História da Matemática e Música: Conexões Interdisciplinares." REMATEC 16 (February 2, 2021): 01–15. http://dx.doi.org/10.37084/rematec.1980-3141.2021.n.p01-15.id319.
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O escopo do presente trabalho é investigar as conexões interdisciplinares entre a Neurociência, a História da Matemática e a Música. Serão discutidos avanços da Neurociência, como a Lei de Weber-Fechner, sistemas de representação de valores numéricos, com enfase no (ANS-Approximate Number System) e como as frações seão representações inatas não simbólicas de magnitudes analógicas. Com base nesses avanços, serão analisadas quais escalas musicais, cujas frações intercalares a História da Matemática registra, melhor se adequem ao sistema ANS.
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Jenkins, J. T., and M. W. Richman. "Plane simple shear of smooth inelastic circular disks: the anisotropy of the second moment in the dilute and dense limits." Journal of Fluid Mechanics 192 (July 1988): 313–28. http://dx.doi.org/10.1017/s0022112088001879.
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We consider a plane, steady, homogeneous flow of circular disks. The disks are identical, smooth, and inelastic. We adopt the assumption of molecular chaos and introduce an anisotropic Maxwellian velocity distribution function based on the full second moment of the velocity fluctuations. In the limits of dilute and dense flows, we determine approximate analytic solutions of the balance law for the second moment that result in stresses whose qualitative behaviour and magnitudes are in good agreement with numerical simulations.
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Brezis, Noam, Zohar Z. Bronfman, Noa Jacoby, Michal Lavidor, and Marius Usher. "Transcranial Direct Current Stimulation over the Parietal Cortex Improves Approximate Numerical Averaging." Journal of Cognitive Neuroscience 28, no. 11 (November 2016): 1700–1713. http://dx.doi.org/10.1162/jocn_a_00991.
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The parietal cortex has been implicated in a variety of numerosity and numerical cognition tasks and was proposed to encompass dedicated neural populations that are tuned for analogue magnitudes as well as for symbolic numerals. Nonetheless, it remains unknown whether the parietal cortex plays a role in approximate numerical averaging (rapid, yet coarse computation of numbers' mean)—a process that is fundamental to preference formation and decision-making. To causally investigate the role of the parietal cortex in numerical averaging, we have conducted a transcranial direct current stimulation (tDCS) study, in which participants were presented with rapid sequences of numbers and asked to convey their intuitive estimation of each sequence's average. During the task, the participants underwent anodal (excitatory) tDCS (or sham), applied either on a parietal or a frontal region. We found that, although participants exhibit above-chance accuracy in estimating the average of numerical sequences, they did so with higher precision under parietal stimulation. In a second experiment, we have replicated this finding and confirmed that the effect is number-specific rather than domain-general or attentional. We present a neurocomputational model postulating population-coding underlying rapid numerical averaging to account for our findings. According to this model, stimulation of the parietal cortex elevates neural activity in number-tuned dedicated detectors, leading to increase in the system's signal-to-noise level and thus resulting in more precise estimations.
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Al Jawarneh, Isam Mashhour, Paolo Bellavista, Antonio Corradi, Luca Foschini, and Rebecca Montanari. "QoS-Aware Approximate Query Processing for Smart Cities Spatial Data Streams." Sensors 21, no. 12 (June 17, 2021): 4160. http://dx.doi.org/10.3390/s21124160.
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Large amounts of georeferenced data streams arrive daily to stream processing systems. This is attributable to the overabundance of affordable IoT devices. In addition, interested practitioners desire to exploit Internet of Things (IoT) data streams for strategic decision-making purposes. However, mobility data are highly skewed and their arrival rates fluctuate. This nature poses an extra challenge on data stream processing systems, which are required in order to achieve pre-specified latency and accuracy goals. In this paper, we propose ApproxSSPS, which is a system for approximate processing of geo-referenced mobility data, at scale with quality of service guarantees. We focus on stateful aggregations (e.g., means, counts) and top-N queries. ApproxSSPS features a controller that interactively learns the latency statistics and calculates proper sampling rates to meet latency or/and accuracy targets. An overarching trait of ApproxSSPS is its ability to strike a plausible balance between latency and accuracy targets. We evaluate ApproxSSPS on Apache Spark Structured Streaming with real mobility data. We also compared ApproxSSPS against a state-of-the-art online adaptive processing system. Our extensive experiments prove that ApproxSSPS can fulfill latency and accuracy targets with varying sets of parameter configurations and load intensities (i.e., transient peaks in data loads versus slow arriving streams). Moreover, our results show that ApproxSSPS outperforms the baseline counterpart by significant magnitudes. In short, ApproxSSPS is a novel spatial data stream processing system that can deliver real accurate results in a timely manner, by dynamically specifying the limits on data samples.
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Du, Ying, and Changlin Mei. "A Compensated Numerical Method for Solving Stochastic Differential Equations with Variable Delays and Random Jump Magnitudes." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/810160.
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Stochastic differential equations with jumps are of a wide application area especially in mathematical finance. In general, it is hard to obtain their analytical solutions and the construction of some numerical solutions with good performance is therefore an important task in practice. In this study, a compensated split-stepθmethod is proposed to numerically solve the stochastic differential equations with variable delays and random jump magnitudes. It is proved that the numerical solutions converge to the analytical solutions in mean-square with the approximate rate of 1/2. Furthermore, the mean-square stability of the exact solutions and the numerical solutions are investigated via a linear test equation and the results show that the proposed numerical method shares both the mean-square stability and the so-called A-stability.
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Marthinsen, K., and R. Høier. "On the determination of enanttomorphs from non-systematic many-beam effects in CBED patterns." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 484–85. http://dx.doi.org/10.1017/s0424820100154391.
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A convergent beam electron diffraction (CBED) method which makes it possible to determine structure factor magnitudes and phases with high accuracy has recently been suggested. It is based on detailed simulations of non-systematic many-beam diffraction effects in the disks. Basis for the phase determination is an asymmetry which may appear in a line h with respect to the Bragg condition of the coupled reflection g near a three-beam condition. Approximate analytical three-beam solutions show that the sign and size of this asymmetry depends on the structure factor phases Θh of the reflections h involved through a term cos(Φ) where Φ is the three phase structure invariant, Φ = Θh + Θg + Θh-g. The magnitude of the phase invariant is thus in principle available, but not the sign. The aim of the present work has been to discuss the origin of the sign problem and the possibilities of distinguishing +/−Φ.
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Li, Zhigang. "Closure to Discussion on “Approximate Linear Power Flow Using Logarithmic Transform of Voltage Magnitudes With Reactive Power and Transmission Loss Consideration”." IEEE Transactions on Power Systems 34, no. 5 (September 2019): 3985. http://dx.doi.org/10.1109/tpwrs.2019.2932636.
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Sturman, V. I. "The pattern of power frequency electromagnetic fields in the Pushkin municipal area of Saint Petersburg." Известия Русского географического общества 151, no. 6 (December 20, 2019): 58–68. http://dx.doi.org/10.31857/s0869-6071151658-68.
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The study of patterns of electric fields intensity indicators and amagnetic induction in the Pushkin municipal area of Saint Petersburg has been executed. It is established that intensity of electric fields reaches significant sizes only near to air high-voltage transmission lines. Magnetic induction over admissible levels is not noted, but within city territory its size change largely that had been represented on the original map. The dependence of indicators of magnetic induction on the land use and building of territories in Pushkin is rather simple: the minimum values are registered in the parks, squares and boulevards, the averages are in the built-up territories, the raised are in anomalies. Magnitudes over hygienic standard are not noted. Magnitudes over the approximate safer limit 400nTl are observed in Pushkin area only in places of underground cables. As awhole, the Pushkin area is characterized by the indicators of magnetic induction lowered in comparison with another cities.
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SRIVASTAVA, H. N., R. K. SINGH, DAL SINGH, RAJESH PRAKASH, and A. K. SHUKLA. "Bhuj (2001) aur Muzaffarabad (2005) bhukampon ke purv tatha baad ke bhukampon ka tulnatmak addhyayan." MAUSAM 64, no. 2 (April 1, 2013): 323–44. http://dx.doi.org/10.54302/mausam.v64i2.5868.
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Bhuj (2001) and Muzaffarabad (2005) earthquakes of same moment magnitude of Mw : 7.6 occured in different techtonic regions i.e., intraplate and interplate regions of Indo-Eurasian plates respectevely. Keeping this in view, their comparative study has been attempted in this paper. A detailed catalogue of earthquakes has been prepared to study seismicity of Kutchh region by including historical and paleoseismic data. Discussion on seismicity of Muzaffarabad (2005) earthquake is based on IMD catalogoue of earthquakes. Difference has been found between Bhuj (2001) and Muzaffarabad (2005) earthquakes based on their foreshocks, magnitudes of aftershocks and their decay, b-value and their spectra. Though no relation between magnitudes of aftershocks and stress drop could be found but mostly the corner frequency and magnitude are inversely related. Difference in both these large earthquakes (M>=7.6) occurring in different tectonic plate set up is clearly evident from their stress drop. Seismic gap is noticed prior to main event of Muzaffarabad earthquake; which is similar to other Himalayan earthquakes of that region like Uttarkashi (1991) and Chamoli (1999). From the point of view earthquake prediction, the results based on satellite thermal anamolies, ionosphere, electromagnetic and sodar observations reported for these earthquakes are considered to be of limited value due to the large influence of atmospheric parameters. Though approximate displacement measured through GPS is useful for calculating the plate motion but their results to derive large vertical displacement is questionable in any case of Bhuj earthquake due to use of standard radio atmosphere. The errors in such results can be reduced by adopting radio atmosphere for the Indian region. Through a review of methodologies to predict the strong ground motion in the near field, it is evident that further research is called for.
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Nguyen, Thi Mai, Hong Phuong Nguyen, Van Phong Vu, The Truyen Pham, and Thi Nhung Bui. "Seismic activity in the continental shelf of South-Central Vietnam and adjacent regions from 2005 to 2020." Tạp chí Khoa học và Công nghệ Biển 22, no. 2 (June 21, 2022): 143–54. http://dx.doi.org/10.15625/1859-3097/16519.
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Since 2005, 10 seismic monitoring stations have been installed in the southern part of Vietnam. These stations can detail the earthquakes in the region and adjacent areas. In the past, there was an earthquake of magnitude 6.1 (1923) in the offshore South-Central Part related to the Hon Tro eruption, the largest observed earthquake magnitude in the 20th century. Between 2005 and 2020, 371 earthquakes were recorded with magnitudes ranging from 0.7 to 5.3. Most of events were distributed on some northeast-southwest direction faults in South Central offshore. The magnitude of the representative earthquake was relatively small, Mc = 2.2, so it is assumed that this research area was of weak activity. The epicenter is about < 20 km, and the majority concentration is at a relatively shallow depth of 5km and still located in the crust of Earth. The relationship between earthquake magnitude and frequency in this region is as follows: lgN = 4.063 – 0.694*M for the entire catalog of 371 events and lgN = 3.826 – 0.704*M after filtering 92 foreshocks and aftershocks of the earthquakes M = 5.3 on November 8th, 2005, and M = 5.2 on November 28th, 2007. So, the calculated average b-values before and after filtering foreshocks and aftershocks were approximately 0.7. These values are almost approximate to the b-value of 0.76 determined by Pham Van Thuc et al., (2004) based on the East Vietnam Sea earthquake catalog from 1903 to 2002 and smaller than the b-value of 0.92 for triggered earthquakes in the Song Tranh 2 hydropower region. In addition, oil and gas exploitation activities are still taking place in the South-Central continental shelf; it is necessary to continue collecting earthquake data to elucidate the causes of earthquakes in the study region.
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Ashkenazi, Sarit, and Yulia Tsyganov. "The Cognitive Estimation Task is nonunitary: Evidence for multiple magnitude representation mechanisms among normative and ADHD college students." Journal of Numerical Cognition 2, no. 3 (February 10, 2017): 220–46. http://dx.doi.org/10.5964/jnc.v2i3.3.
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There is a current debate on whether the cognitive system has a shared representation for all magnitudes or whether there are unique representations. To investigate this question, we used the Biber cognitive estimation task. In this task, participants were asked to provide estimates for questions such as, “How many sticks of spaghetti are in a package?” The task uses different estimation categories (e.g., time, numerical quantity, distance, and weight) to look at real-life magnitude representations. Experiment 1 assessed (N = 95) a Hebrew version of the Biber Cognitive Estimation Task and found that different estimation categories had different relations, for example, weight, time, and distance shared variance, but numerical estimation did not. We suggest that numerical estimation does not require the use of measurement in units, hence, it represents a more “pure” numerical estimation. Experiment 2 found that different factors explain individual abilities in different estimation categories. For example, numerical estimation was predicted by preverbal innate quantity understanding (approximate number sense) and working memory, whereas time estimations were supported by IQ. These results demonstrate that cognitive estimation is not a unified construct.
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Panda, B. B., M. L. Rucker, and K. C. Fergason. "Modeling of earth fissures caused by land subsidence due to groundwater withdrawal." Proceedings of the International Association of Hydrological Sciences 372 (November 12, 2015): 69–72. http://dx.doi.org/10.5194/piahs-372-69-2015.
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Abstract. Land subsidence and earth fissures are phenomena related to groundwater withdrawal in a sedimentary basin. If the rock basement or basin lithology is irregular, both vertical and horizontal displacements can be induced due to differential settlement and tensile stresses appearing in the soil mass. If the differential settlement is of sufficient magnitude, earth fissuring can occur within tensile zones. The magnitudes of compaction and fissure geometry are closely related to the thickness and skeletal compressibility of fine-grained sediments within the aquifer system. Land subsidence and earth fissuring were modeled by employing a two-dimensional (2-D) coupled seepage and stress-strain finite element analysis. The basin bedrock geometry, lithological variation, measurements of surface displacements, and changes in hydraulic head were the critical input parameter for the subsidence modeling. Simulation results indicate that strain had exceeded the approximate threshold for fissure formation of 0.02 to 0.06 % in the area of the identified fissures. The numerical model was used to predict future subsidence and potential earth fissures for flood control structures within the metro Phoenix area.
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Chiang, L. E., and E. B. Stamm. "Design Optimization of Valveless DTH Pneumatic Hammers by a Weighted Pseudo-Gradient Search Method." Journal of Mechanical Design 120, no. 4 (December 1, 1998): 687–94. http://dx.doi.org/10.1115/1.2829332.
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A design methodology for Down-The-Hole (DTH) pneumatic hammers used for rock drilling is proposed which renders an optimal design for a given set of constraints. A generic non-linear dynamic model developed by the authors is used to compute the hammer performance. This model consists of a set of six differential equations plus a set of twenty non-linear polynomial equations. In addition there are parameter range restrictions given by fabrication and operational standard procedures. In any given application, magnitudes such as power, impact energy, frequency, efficiency and mass flow may be sought for optimality. However these magnitudes must be computed by integration after solving the dynamic model over an entire cycle, thus traditional optimization methods for non-linear equations that are based in gradient information are not suitable. Hence a method that uses secant information is used to approximate the gradient of the space of design variables. Several prototypes using this optimization method have been designed and field tested. The results are in agreement with predicted values.
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Dorset, D. L., M. P. McCourt, W. F. Tivol, and J. N. Turner. "Electron diffraction from phospholipids – an approximate correction for dynamical scattering and tests for a correct phase determination." Journal of Applied Crystallography 26, no. 6 (December 1, 1993): 778–86. http://dx.doi.org/10.1107/s0021889893005394.
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An approximate experimental correction of electron diffraction intensities from an epitaxically crystallized phospholipid bilayer for dynamical scattering is described. This correction, which is useful for certain low-angle centrosymmetric data sets, compares intensities recorded at high and low electron-accelerating voltages to ascertain which reflections are most affected by n-beam interactions. When applied to experimental intensity data from 1,2-dihexadecyl-sn-glycerophosphoethanolamine (DHPE), the correction facilitates a direct phase determination based on the probabilistic estimate of three-phase invariants because a more accurate estimate of the hierarchy of |El | values is obtained. When a multisolution technique is used, incorporating algebraic unknowns for certain phase values, the best phase assignment can be assessed by comparison of the single convolution of phased structure factors to the observed structure-factor magnitudes for the low-voltage data. This approach exploits an approximate analogy made earlier by Moodie between the Sayre equation and the phase grating series and is valid as long as the single convolution adequately models experimental low-voltage data (a condition favored by light-atom structures in a low-angle region of reciprocal space). In real space, the correct structure can also be readily identified as the one having the smoothest density profile.
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Tortorelli, Luca, Malgorzata Siudek, Beatrice Moser, Tomasz Kacprzak, Pascale Berner, Alexandre Refregier, Adam Amara, et al. "The PAU survey: measurement of narrow-band galaxy properties with approximate bayesian computation." Journal of Cosmology and Astroparticle Physics 2021, no. 12 (December 1, 2021): 013. http://dx.doi.org/10.1088/1475-7516/2021/12/013.
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Abstract Narrow-band imaging surveys allow the study of the spectral characteristics of galaxies without the need of performing their spectroscopic follow-up. In this work, we forward-model the Physics of the Accelerating Universe Survey (PAUS) narrow-band data. The aim is to improve the constraints on the spectral coefficients used to create the galaxy spectral energy distributions (SED) of the galaxy population model in Tortorelli et al. 2020. In that work, the model parameters were inferred from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) data using Approximate Bayesian Computation (ABC). This led to stringent constraints on the B-band galaxy luminosity function parameters, but left the spectral coefficients only broadly constrained. To address that, we perform an ABC inference using CFHTLS and PAUS data. This is the first time our approach combining forward-modelling and ABC is applied simultaneously to multiple datasets. We test the results of the ABC inference by comparing the narrow-band magnitudes of the observed and simulated galaxies using Principal Component Analysis, finding a very good agreement. Furthermore, we prove the scientific potential of the constrained galaxy population model to provide realistic stellar population properties by measuring them with the SED fitting code CIGALE. We use CFHTLS broad-band and PAUS narrow-band photometry for a flux-limited (i < 22.5) sample of galaxies up to redshift z ∼ 0.8. We find that properties like stellar masses, star-formation rates, mass-weighted stellar ages and metallicities are in agreement within errors between observations and simulations. Overall, this work shows the ability of our galaxy population model to correctly forward-model a complex dataset such as PAUS and the ability to reproduce the diversity of galaxy properties at the redshift range spanned by CFHTLS and PAUS.
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Lunin, V. Y., N. L. Lunina, and T. E. Petrova. "Mask-Based Approach in Phasing and Restoring of Single-Particle Diffraction Data." Mathematical Biology and Bioinformatics 15, no. 1 (March 2, 2020): 57–72. http://dx.doi.org/10.17537/2020.15.57.
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The development of experimental techniques, in particular the emergence of the X-ray free-electron lasers, allows one to register the scattering from an isolated particle and, thereby, opens a door to the study of a fine three-dimensional structure of non-crystalline biological objects by X-ray diffraction methods. The possibility to measure non-Bragg reflections makes experimental data mutually dependent and essentially simplifies the structure solution. The sampling of experimental scattering data to a sufficiently fine grid makes the structure determination equivalent to phasing of structure factor magnitudes for a 'virtual' crystal with extremely large solvent content. This makes density modification phasing methods especially powerful supposing the object envelope is known. At the same time, such methods may be sensitive to the accuracy of the predefined envelope and completeness of experimental data and may suffer from non-uniqueness of the solution of the phase problem. The mask-based approach is a preliminary phasing method that performs random search for connected object envelopes possessing of the structure factor magnitudes close to the values observed in X-ray experiment. The alignment and averaging of the phase sets corresponding to selected putative envelopes produce an approximate solution of the phase problem. Beside the estimation of unknown phase values this approach allows one to estimate the values of structure factor magnitudes lost in the experiment, e.g. those corresponding to beam-stop shade zone or to oversaturated reflections.
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Menq, C. H., J. H. Griffin, and J. Bielak. "The Influence of a Variable Normal Load on the Forced Vibration of a Frictionally Damped Structure." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 300–305. http://dx.doi.org/10.1115/1.3239903.
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An approximate procedure is developed for calculating the steady-state response of frictionally damped structures for which the normal load across the friction interface consists of a constant force and a force that varies linearly with the vibratory displacement. Such situations occur quite frequently in practice, as, for example; in the case of shrouded fan blades or in certain types of turbine-blade friction dampers. Depending on the magnitudes of the constant and the variable normal loads, the friction element will either stick, slip, or lift off at various intervals during a cycle of oscillation. The various possibilities are considered in the present study. Results from the approximate method are compared with “long-time” solutions obtained from a conventional transient analysis of the problem in order to assess the accuracy of the proposed procedure. As an application, the new method is then used to study the influence of the dynamic coupling on the optimization of the friction force in turbine blade dampers. Results show that the optimum friction force and the maximum amplitude of the response increase with dynamic coupling.
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Shragge, Jeffrey, and David Lumley. "Time-lapse wave-equation migration velocity analysis." GEOPHYSICS 78, no. 2 (March 1, 2013): S69—S79. http://dx.doi.org/10.1190/geo2012-0182.1.
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Time-lapse (4D) analysis of seismic data acquired at different stages of hydrocarbon production or gas/fluid injection has been very successful at imaging detailed reservoir changes. Conventional time-domain analysis of 4D data sets usually assumes a linear perturbation about a reference baseline earth model. However, this assumption is violated when production/injection significantly alters the subsurface generating large 4D velocity changes, time shifts, and complicated 4D wavefield coda, necessitating a more robust 4D analysis involving prestack wave-equation depth migration and velocity analysis. We address these situations by extending conventional 3D wave-equation migration velocity analysis (WEMVA) based on one-way wave-equations and single-scattering theory to 4D velocity estimation using a “parallel” inversion approach involving parallel solution of two separate inversion problems. Recognizing that the 4D WEMVA strategy requires precomputed baseline/monitor image-difference volumes, we develop an approximate 4D WEMVA technique that replaces these differences with a single weight function derived from the smooth background time-lapse image difference. We demonstrate the usefulness of the parallel and an approximate 4D WEMVA approach using a synthetic time-lapse [Formula: see text] geosequestration experiment that requires inverting for a thin-layer velocity change derived from [Formula: see text] injection in an analogue North Sea reservoir. The parallel 4D WEMVA solutions generate an excellent high-resolution velocity estimates, whereas the approximate methods recover lower-resolution estimates with magnitudes that must be rescaled through a post-inversion gradient line-search.
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Lu, P. X., D. A. Huber, and T. L. White. "Potential biases of incomplete linear models in heritability estimation and breeding value prediction." Canadian Journal of Forest Research 29, no. 6 (June 1, 1999): 724–36. http://dx.doi.org/10.1139/x99-047.
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Potential biases associated with incomplete linear models in the estimation of heritability and the prediction of breeding values have been investigated. Results indicate that estimates of additive genetic variance and heritability as well as predicted parental breeding values from incomplete models will inevitably be biased as long as the true variance components of ignored effects are not zero. While models ignoring the interaction effect of males and females (SCA) × environment (E) interaction downwardly biased the estimates of additive genetic variance and heritability, models ignoring SCA and (or) the additive genetic effect (GCA) × E interaction yielded upward biases. The magnitudes of biases are functions of population genetic architecture, mating design, and field experimental design and can be precisely assessed with formulae derived for balanced data. Numerical simulations using unbalanced data of different mating and field experimental designs suggest that the formulae from balanced data can be used to approximate the minimum biases associated with unbalanced data. Because of the magnitudes of biases for some typical forest genetic scenarios, it is suggested that models ignoring SCA and (or) GCA × E should be avoided when the numbers of test sites and crosses per parent are small. However, incomplete model ignoring SCA × E interaction may be used to reduce computational demand with only negligible consequences.
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Tarassov, Jevgeni, and Nicolas Houlié. "Bitcoin: A life in crises." PLOS ONE 17, no. 9 (September 30, 2022): e0274165. http://dx.doi.org/10.1371/journal.pone.0274165.
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In this study, we investigate the BTC price time-series (17 August 2010–27 June 2021) and show that the 2017 pricing episode is not unique. We describe at least ten new events, which occurred since 2010–2011 and span more than five orders of price magnitudes ($US 1 –$US 60k). We find that those events have a similar duration of approx. 50–100 days. Although we are not able to predict times of a price peak, we however succeed to approximate the BTC price evolution using a function that is similar to a Fibonacci sequence. Finally, we complete a comparison with other types of financial instruments (equities, currencies, gold) which suggests that BTC may be classified as an illiquid asset.
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Christov, C., S. Gabriel, B. Atanasov, and J. Fleischhauer. "Calculation of the CD Spectrum of Class A β-Lactamase from Escherichia coli (TEM-1)." Zeitschrift für Naturforschung A 56, no. 11 (November 1, 2001): 757–60. http://dx.doi.org/10.1515/zna-2001-1111.
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Abstract The Circular Dichroism (CD) spectrum of β-lactamase from Escherichia coli (TEM-1) has been calculated with the matrix method on the basis of the x-ray diffraction structure. All known transitions in the peptide and side-chain groups, especially the aromatic and disulfide groups have been included. The calculations were performed with and without the tryptophan (Trp) residues. Rotational strengths calculated with the matrix method were combined with Gaussians to generate the CD spectrum. The calculated spectrum reproduces the signs and approximate magnitudes of the CD bands rather w ell only when the trytophan side chains are included. However, the experimental negative double band at 208 and 222 nm, which is characteristic for a-helices, is absent in the calculated spectrum.
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Darbandi, Masoud, and Gerry E. Schneider. "Thermobuoyancy Treatment for Electronic Packaging Using an Improved Advection Scheme." Journal of Electronic Packaging 125, no. 2 (June 1, 2003): 244–50. http://dx.doi.org/10.1115/1.1569508.
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The complex nature of the convective terms in the fluid flow governing equations has caused many researchers to work on estimating more accurate advection term magnitudes by employing better approximate expressions. The trend of progress has been to include more physics of flow in the approximations. However, there is no archival evidence that reports the direct implementation of buoyancy as a physical influence in the advection term modeling. In this work, the influence of buoyancy in an efficient advection term expression is investigated in a control volume context with a collocated grid arrangement. The accuracy of the results obtained by both excluding and including the buoyancy term is evaluated through application to the natural convection heat transfer problem in a cavity at different Rayleigh numbers.
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Namboodiri, Vijay Mohan K., Stefan Mihalas, and Marshall G. Hussain Shuler. "Analytical Calculation of Errors in Time and Value Perception Due to a Subjective Time Accumulator: A Mechanistic Model and the Generation of Weber’s Law." Neural Computation 28, no. 1 (January 2016): 89–117. http://dx.doi.org/10.1162/neco_a_00792.
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It has been previously shown (Namboodiri, Mihalas, Marton, & Hussain Shuler, 2014 ) that an evolutionary theory of decision making and time perception is capable of explaining numerous behavioral observations regarding how humans and animals decide between differently delayed rewards of differing magnitudes and how they perceive time. An implementation of this theory using a stochastic drift-diffusion accumulator model (Namboodiri, Mihalas, & Hussain Shuler, 2014a ) showed that errors in time perception and decision making approximately obey Weber’s law for a range of parameters. However, prior calculations did not have a clear mechanistic underpinning. Further, these calculations were only approximate, with the range of parameters being limited. In this letter, we provide a full analytical treatment of such an accumulator model, along with a mechanistic implementation, to calculate the expression of these errors for the entirety of the parameter space. In our mechanistic model, Weber’s law results from synaptic facilitation and depression within the feedback synapses of the accumulator. Our theory also makes the prediction that the steepness of temporal discounting can be affected by requiring the precise timing of temporal intervals. Thus, by presenting exact quantitative calculations, this work provides falsifiable predictions for future experimental testing.
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Orujov, Gurban, Rita Streich, and Andrei Swidinsky. "Modeling and inversion of electromagnetic data collected over steel casings: An analysis of two controlled field experiments in Colorado." Leading Edge 41, no. 2 (February 2022): 114–21. http://dx.doi.org/10.1190/tle41020114.1.
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Modeling and inversion of electromagnetic (EM) data contaminated by steel infrastructure remains a numerically challenging task. In this study, we collected controlled-source EM (CSEM) field data at two test sites. First, we conducted a CSEM survey over a dry and abandoned well in eastern Colorado. Next, we collected CSEM data over a test well located at the Colorado School of Mines. The purpose of these experiments was to examine methods to invert EM data contaminated by infrastructure effects and recover undistorted subsurface conductivity models. We used a hybrid approach to model casing effects by considering the conductive metal as a distribution of secondary sources with magnitudes calculated using an approximate layered background. In particular, we applied the method of moments algorithm to calculate the magnitude of the secondary electric dipole sources along the casing. Subsequently, we included these secondary sources in a 3D finite-volume-based forward calculation and used the Gauss-Newton method to invert the contaminated field data. As expected, our preliminary inversion results show that by not considering casing effects, significant artifacts are introduced in the recovered models. Furthermore, we show that such artifacts are reduced significantly through the introduction of casing physics in the forward model, enabling the surrounding subsurface conductivity and corresponding geology to be characterized.
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Aziz, A. F., N. H. Mardi, and M. A. Malek. "Projection of Tsunami Wave Height at East-Coast of Peninsular Malaysia using Green’s Law." International Journal of Engineering & Technology 7, no. 4.35 (November 30, 2018): 270. http://dx.doi.org/10.14419/ijet.v7i4.35.22745.
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In recent years, studies regarding a new source of tsunami-genic earthquake at South China Sea region known as Manila Trench earthquake have attracted the attention of many researchers. It is expected that this subduction zone is capable to trigger large moment magnitude earthquake and affects countries located within South China Sea. The objective of this study is to project tsunami wave height and arrival time generated from Manila Trench earthquake towards coastal areas located along east-coast of Peninsular Malaysia. This study focuses on simulating tsunami at four different moment magnitudes by using TUNA-M2 model to record wave height and arrival time at the offshore areas. Then the Green’s law is used to approximate reliable tsunami wave height when approaching onshore. Results obtained in this study showed that tsunami waves from Manila Trench are estimated to arrive at coastal areas of east-coast Peninsular Malaysia between 9.1 to 10.25 hours post-earthquake occurrence. The observation points located at offshore of Kelantan are anticipated to experience the highest wave height as compared to other observation points located at offshore areas of Terengganu and Pahang. This study is important to the coastal communities as it provides vital information on possible tsunami occurrences in the future.
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Perras, Frédéric A., and David L. Bryce. "A ZORA-DFT and NLMO study of the one-bond fluorine–X indirect nuclear spin-spin coupling tensors for various VSEPR geometries." Canadian Journal of Chemistry 89, no. 7 (July 2011): 789–802. http://dx.doi.org/10.1139/v10-172.
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Zeroth-order regular approximation (ZORA) density functional theory (DFT) calculations of one-bond X–19F indirect nuclear spin-spin coupling (J) tensors were performed on a series of fluorine-containing compounds covering several valence shell electron pair repulsion (VSEPR) theory geometries for which J, by symmetry, is not required to be axially symmetric. The calculations show that the antisymmetric components of J are only of the same order of magnitude as the principal components of the symmetric J-coupling tensor for a few geometries, and that in cases of approximate axial symmetry along the bond, J remains nearly axially symmetric with its unique component along the bond. In general, different species having the same nominal geometry tend to have similar tensor orientations, magnitudes of anisotropy of J relative to the isotropic coupling constant, as well as the same dominant contributions from the different coupling mechanisms. Structures are also systematically modified to determine how the tensor components depend on geometrical parameters. The isotropic coupling constants are subsequently interpreted using a natural localized molecular orbital (NLMO) approach. Our results could prove to be useful for future experimental characterizations of J tensors in systems having symmetry properties that do not force J to be axially symmetric or coincident with the dipolar coupling tensor.