Multiple Traces Research Articles

Stacking Seismic Data Based on Ramanujan Sums

Real seismic data consist of multiple traces captured by an array of receivers. These multiple traces are sorted by the common midpoint between the source and the receiver, and the time-lag between different traces is corrected by a normal move-out correction process. After these preprocessing steps, the sorted traces contain the same information about the earth sublayers and are corrupted by noise. The next step, termed stacking in seismic signal processing, involves the construction of an optimum trace with an improved signal-to-noise ratio (SNR) from these sorted traces. In this letter, we present an improved method for weighted stacking, where each trace is weighed in accordance with the noise variance. Using the first-order derivative property of Ramanujan sums, we perform the estimation of noise variance in each trace. Numerical results demonstrate that the method presented in this letter has better SNR for the trace obtained after stacking in comparison with existing methods.

Plate boundary localization, slip-rates and rupture segmentation of the Queen Charlotte Fault based on submarine tectonic geomorphology

Linking fault behavior over many earthquake cycles to individual earthquake behavior is a primary goal in tectonic geomorphology, particularly across an entire plate boundary. Here, we examine the 1150-km-long, right-lateral Queen Charlotte-Fairweather fault system using comprehensive multibeam bathymetry data acquired along the Queen Charlotte Fault (QCF) offshore southeastern Alaska and western British Columbia. Fine-scale analysis of tectonic geomorphology allowed us to identify and reconstruct 184 strike-slip piercing points over a 630 km stretch of the QCF. Age constraints from glacial recession and offshore sedimentation patterns yield a consistent slip-rate of ∼50–57 mm/yr since ∼17–12 ka, the fastest rate for a continent-ocean strike-slip fault on Earth. These slip-rates equal or exceed estimates of Pacific-North America (PA-NA) relative motion from global plate reconstructions, indicating that PA-NA motion is highly localized. The QCF cuts the seafloor along a narrow and unusually straight trace for its entire length and multiple fault traces are observed only at local step-overs. The geometry and behavior of the QCF over many earthquake cycles is simple and typical of mature faults with relatively homogeneous stress fields. Since the QCF is the primary PA-NA plate boundary, we used the trace of the QCF to define the small circle path for relative plate motion and computed the associated Euler pole. Predicted along-strike obliquity variations based on the new pole agree with observed tectonic geomorphology and suggest that previous global plate reconstructions overestimated the degree of oblique convergence along the QCF. We also find that subtle, long-wavelength (75–150 km) bends and discrete step-overs appear to define the endpoints of M>7 earthquakes, suggesting that obliquity and resultant fault geometry may control rupture segmentation and asperity development. Lastly, the agreement between predicted obliquity and tectonic geomorphology along the entire length of QCF compelled a reevaluation of regional tectonic models. In the north, the eastern Yakatat Terrane appears to be translating northwest with the Pacific plate, and slip transferred from the QCF to the Fairweather Fault results in ∼20 mm/yr of convergence along the southern St. Elias mountains. In the south, we predict a reduced rate of convergence along the QCF west of Haida Gwaii (∼5–6 mm/yr of shortening, on average) relative to previous studies. Our results support a model for transpression and strike-slip partitioning along the edge of a hot and weak Pacific Plate, leading to crustal thickening and growth of the Queen Charlotte Terrace to the west of Haida Gwaii.

Has multiple trace theory been refuted?

Multiple trace theory (Nadel & Moscovitch, Current Opinion in Neurobiology, 1997, 7, 217-227) has proven to be one of the most novel and influential recent memory theories, and played an essential role in shifting perspective on systems-level memory consolidation. Here, we briefly review its impact and testable predictions and focus our discussion primarily on nonhuman animal experiments. Perhaps, the most often supported claim is that episodic memory tasks should exhibit comparable severity of retrograde amnesia (RA) for recent and remote memories after extensive damage to the hippocampus (HPC). By contrast, there appears to be little or no experimental support for other core predictions, such as temporally limited RA after extensive HPC damage in semantic memory tasks, temporally limited RA for episodic memories after partial HPC damage, or the existence of storage of multiple HPC traces with repeated reactivations. Despite these shortcomings, it continues to be a highly cited HPC memory theory.

Multimodal Markov chain Monte Carlo method for nonlinear petrophysical seismic inversion

One of the main objectives in the reservoir characterization is estimating the rock properties based on seismic measurements. We have developed a stochastic sampling method for the joint prediction of facies and petrophysical properties, assuming a nonparametric mixture prior distribution and a nonlinear forward model. The proposed methodology is based on a Markov chain Monte Carlo (MCMC) method specifically designed for multimodal distributions for nonlinear problems. The vector of model parameters includes the facies sequence along the seismic trace as well as the continuous petrophysical properties, such as porosity, mineral fractions, and fluid saturations. At each location, the distribution of petrophysical properties is assumed to be multimodal and nonparametric with as many modes as the number of facies; therefore, along the seismic trace, the distribution is multimodal with the number of modes being equal to the number of facies power the number of samples. Because of the nonlinear forward model, the large number of modes and as a consequence the large dimension of the model space, the analytical computation of the full posterior distribution is not feasible. We then numerically evaluate the posterior distribution by using an MCMC method in which we iteratively sample the facies, by moving from one mode to another, and the petrophysical properties, by sampling within the same mode. The method is extended to multiple seismic traces by applying a first-order Markov chain that accounts for the lateral continuity of the model properties. We first validate the method using a synthetic 2D reservoir model and then we apply the method to a real data set acquired in a carbonate field.

Структура, символика и атрибутика ритуальных комплексов периода дзё:мон на Японском архипелаге

Искусство каменного века Японского архипелага тесно связано с разнообразием ритуальных объектов, датируемых финальным палеолитом – эпохой дзё:мон (14–2,3 тыс. л.н.). По своим масштабам они подразделяются на макрокомплексы (каменные круги, насыпи, раковинные кучи) и микрокомплексы (наборы артефактов в жилищах, погребениях, кладах). В свою очередь, в пределах макрокомплексов (о-ва Хоккайдо, Хонсю) выделяются мегалитические структуры с горизонтальной и вертикальной ориентацией, они сопровождаются массовыми находками изделий мелкой глиняной пластики, фрагментами керамических сосудов с антропоморфной и зооморфной символикой, украшениями из мягкого камня. Особое место занимают каменные жезлы сэкибо: – их размеры варьируются от нескольких сантиметров до 2,5 м, каменные жезлы встречаются как в микро-, так и в макрокомплексах. Несмотря на кислотные почвы, разрушительно действующие на органику, многочисленные следы столбовых ям и широкий диапазон деревообрабатывающих инструментов позволяют с уверенностью предполагать, что вертикальные мегалиты предварялись и дополнялись серией деревянных конструкций. Японские материалы органично вписываются, с одной стороны, в общеевразийский контекст вертикальных мегалитов и деревянных идолов, а с другой – в круг древних культур тихоокеанского бассейна (Юго-Восточная Азия, Океания, побережья Северной и Южной Америк), насыщенных традициями изготовления каменных и деревянных тотемных столбов с ярусной организацией символов и мифологических персонажей.

Analysing user identity via time-sensitive semantic edit distance (t-SED): a case study of Russian trolls on Twitter

In the digital era, individuals are increasingly profiled and grouped based on the traces they leave behind in online social networks such as Twitter and Facebook. In this paper, we develop and evaluate a novel text analysis approach for studying user identity and social roles by redefining identity as a sequence of timestamped items (e.g. tweet texts). We operationalise this idea by developing a novel text distance metric, the time-sensitive semantic edit distance (t-SED), which accounts for the temporal context across multiple traces. To evaluate this method we undertake a case study of Russian online-troll activity within US political discourse. The novel metric allows us to classify the social roles of trolls based on their traces, in this case tweets, into one of the predefined categories left-leaning, right-leaning, and news feed. We show the effectiveness of the t-SED metric to measure the similarities between tweets while accounting for the temporal context, and we use novel data visualisation techniques and qualitative analysis to uncover new empirical insights into Russian troll activity that have not been identified in previous work. Additionally, we highlight a connection with the field of Actor-Network Theory and the related hypotheses of Gabriel Tarde, and we discuss how social sequence analysis using t-SED may provide new avenues for tackling a longstanding problem in social theory: how to analyse society without separating reality into micro versus macro levels.

Reclaiming the aesthetic of women: de-colonizing land ownership

ABSTRACTThis paper engages with the study of the aesthetic as an embodied form and offers a critique of the study of value and commodification that emerges in the global spatial imagination. I explore the neglected interrelationship between cultural-spatial reconstruction and land ownership as a sign of livelihood by way of a critique of development and through an investigation of the multiple traces of colonialism in Indonesia in contemporary times, after the massacres. First, land is taken from communities to be used for state and corporate industrialization, and then aesthetic acts of resistance and remembrance by members of these communities, via artistic productions and protest, are commoditized as touristic attractions by the state as a form of nationalism and fetishism of the indigenous, and by corporations as a form of corporate cultural responsibility. This new method of capitalist inclusion of the survivor in a globalized project of aestheticizing space is a neoliberal tactic in which the commoditized reappearance of the aesthetic creations of the marginalized is not, in fact, a sign of inclusion but rather of further displacement. My study follows the focus of this special issue to analyse cultural production within the complexity of multiple and converging colonial forms in historical and contemporary contexts considering the relationality, contradictions and incommensurabilities generated within converging structures of colonial and racialized violence. I locate the ways in which artistic projects within this schema may be used as acts of resistance but also possibly co-optation/ domination. Aesthetic creations intended as means of archiving may also bring insurrections into the paradigm of globalization and to its attention. This paper is an attempt to look at how the creative urge negates and also creates the possibility of resistance, inviting us to urgently rethink aesthetic projects and their representation through a genealogy of global participation.

Retention time bracketing for targeted sphingolipidomics by liquid chromatography-tandem mass spectrometry.

Aim: In complex biological matrixes, many sphingolipids are present with multiple reaction monitoring traces or lack of standard for verification, potentially leading to inaccurate identification and quantitation. Results/methodology: Based on these retention times of available standards, we devised a retention time bracketing approach to identify and predict sphingolipids of the same homologous series. Excellent concordance of predicted and observed retention times (<0.1 min) of sphingolipids were demonstrated. We also showed that many odd- and/or short-chain sphingolipids, commonly used as internal standards, are present in biological matrices including human serum, peritoneal fluid and cells. Conclusion: A retention time table, and a list of appropriate standards are presented, which are expected to be useful resources in targeted sphingolipidomics.

A New Approach for Recovering High-Level Sequence Diagrams from Object-Oriented Applications Using Petri Nets

Software development starts with sound documentation and design, but during the course of time, design document or other software artifacts are neither updated nor well maintained. It is very essential to understand the existing system to maintain and to evolve it with new requirements. To better understand these legacy systems, we need to extract dynamic behavior and represent it graphically in models. Reverse engineering UML sequence diagrams is a very efficient way to understand the behavior of these systems. Most approaches dealing with this subject, in addition to rarely offer a way to filter source code information, they do not cover all UML control operators such as the operator "par" which is very important in the context of parallelism. In this paper, we propose a new approach to extract UML2 sequence diagrams from multiple execution traces. This approach consists of generating and collecting the corresponding traces of different use cases, filtering and analyzing them using Colored Petri Nets to finally extract a high-level sequence diagram.

The Złota culture grave from Święcica, site 30, Sandomierz district

The paper presents the results of research on a unique Zlota culture niche grave discovered at site 30 in Świecica, Sandomierz district. The construction of the grave, as well as its inventory, bears multiple traces that could be linked to the tradition of the Globular Amphora culture. The structure, dated to the 1st half of the 3rd millennium BC, presents a rare example of funerary rituals using animal remains in the Zlota culture, and sheds new light on the processes of origin of this community.

Automated Neuron Reconstruction from 3D Fluorescence Microscopy Images Using Sequential Monte Carlo Estimation

Microscopic images of neuronal cells provide essential structural information about the key constituents of the brain and form the basis of many neuroscientific studies. Computational analyses of the morphological properties of the captured neurons require first converting the structural information into digital tree-like reconstructions. Many dedicated computational methods and corresponding software tools have been and are continuously being developed with the aim to automate this step while achieving human-comparable reconstruction accuracy. This pursuit is hampered by the immense diversity and intricacy of neuronal morphologies as well as the often low quality and ambiguity of the images. Here we present a novel method we developed in an effort to improve the robustness of digital reconstruction against these complicating factors. The method is based on probabilistic filtering by sequential Monte Carlo estimation and uses prediction and update models designed specifically for tracing neuronal branches in microscopic image stacks. Moreover, it uses multiple probabilistic traces to arrive at a more robust, ensemble reconstruction. The proposed method was evaluated on fluorescence microscopy image stacks of single neurons and dense neuronal networks with expert manual annotations serving as the gold standard, as well as on synthetic images with known ground truth. The results indicate that our method performs well under varying experimental conditions and compares favorably to state-of-the-art alternative methods.

NetStorage: A synchronized trace-driven replayer for network-storage system evaluation

Trace-driven replayers provide a flexible and convenient way to evaluate or debug target systems. Previous researchers focused on the individual impact of either the network or the storage system on overall system performance by using trace-driven replayers. However, as big data and cloud servers become prevalent and the performance gap between storage and networks decreases substantially, it becomes important to consider both impacts of storage and network on target systems. In this paper, we build a replayer called NetStorage to replay the captured traces of both network and storage to evaluate the performance of combined network-storage systems. When involving multiple replayers, the synchronization between these replayers becomes crucial. We introduce a manager component to control the synchronization between replayers. By doing that, the NetStorage is capable of efficiently replaying multiple traces synchronously in order to mimic the real application behavior in network and storage environments for different scenarios. Finally, a case study is provided to compare performance of two systems by using the NetStorage.

Migrating People, Migrating Data: Digital Approaches to Migrant Heritage

Migrants all over the world have left multiple traces in different countries and this cultural heritage is of growing interest for researchers and the migrant community alike. Cultural heritage institutions, however, have dwindling funds and resources to meet this demand. In this article we propose that the key to bridge this gap is to be found in the use of new possibilities in digital collection exploration and resource linking. Building a composite and distributed resource around the migrant's life courses can connect dispersed collections of heritage institutions, provide the community with detailed data about their families and researchers with serial and qualitative data for sophisticated and innovative research. We begin with the Dutch-Australian collaborative project ‘Migrant, Mobilities and Connection’ as a use case and propose that in using this life course-centered methodology may develop into a migration heritage template for migrants worldwide.

Denoising of pre‐stack seismic data using subspace estimation methods

Denoising is one of the core steps in seismic data processing flow. The seismic gather consists of multiple traces captured at different receivers. A set of receivers observe waves which are reflected from the same reflection point. Those traces need to be grouped together as they contain the same information about the earth subsurface layers. This is done by finding a common mid-point (CMP) between the source and geophones. The time delay between CMP gathered traces are corrected by the normal move out correction method but the individual traces are corrupted by noise. In this paper we, propose a method for denoising individual traces. The set of traces can be modelled as belonging to a low-dimensional subspace of an ambient signal space. This allows for construction of sparse representations of each trace in terms of other traces in the CMP gather. The resulting sparse representations are subsequently utilised to construct approximations of individual traces and thus, noise is suppressed. We constructed, the approximations using orthogonal matching pursuit. We applied proposed method to synthetic and field seismic data, the proposed technique performs better on established benchmarks while capturing the true locations of weak reflections and effectively attenuating the random noise.

Dynamic Convolution-based Misfit Function for Time Domain Full Waveform Inversion

Under the same propagation operator, the precision of the seismic wavelet determines whether synthetic data can match field data accurately. By constructing the convolution wavefield objective function, the source difference between simulated and observed data is ignored, thus avoiding the source wavelet estimation. Theoretically, this process has no restriction on the accuracy of the wavelet, and a multi-scale inversion strategy can be implemented by using a source wavelet with different dominant frequencies. When the propagation operator used does not conform with reality, even if both the wavelet and the parameter mode are accurate, it is impossible to simulate the full waveforms of the observed data. Meanwhile, the difference in the Green function brings new discrepancy to the convolution wavefield objective function and affects the final inversion results. The method presented in this paper is based on the convolution wavefield objective function. On the basis of an original single reference trace, we discuss the performance of the convolution wavefield-type objective function under multiple reference traces selected from different offsets. After introducing the changed wavefield information, the objective function has the ability to adapt to different types of data. The analysis shows that nonlinearity is significantly increased after introducing the different wavefield information and also increases with inversion frequency. Even for anisotropic data, it is still possible to give a relatively accurate structure at the low-frequency stage, which shows that the wavefield information from different offsets can help to weaken the artifacts introduced by operator mismatch, thus providing more possibilities for the application of acoustic wave equation inversion.

Fast flow volume estimation

The increasing popularity of jumbo frames means growing variance in the size of packets transmitted in modern networks. Consequently, network monitoring tools must maintain explicit traffic volume statistics rather than settle for packet counting as before. We present constant time algorithms for volume estimations in streams and sliding windows, which are faster than previous work. Our solutions are formally analyzed and are extensively evaluated over multiple real-world packet traces as well as synthetic ones. For streams, we demonstrate a run-time improvement of up to 2.4X compared to the state of the art. On sliding windows, we exhibit a memory reduction of over 100X on all traces and an asymptotic runtime improvement to a constant. Finally, we apply our approach to hierarchical heavy hitters and achieve an empirical 2.4-7X speedup.

Probabilistic programming with programmable inference

We introduce inference metaprogramming for probabilistic programming languages, including new language constructs, a formalism, and the rst demonstration of e ectiveness in practice. Instead of relying on rigid black-box inference algorithms hard-coded into the language implementation as in previous probabilistic programming languages, infer- ence metaprogramming enables developers to 1) dynamically decompose inference problems into subproblems, 2) apply in- ference tactics to subproblems, 3) alternate between incorpo- rating new data and performing inference over existing data, and 4) explore multiple execution traces of the probabilis- tic program at once. Implemented tactics include gradient- based optimization, Markov chain Monte Carlo, variational inference, and sequental Monte Carlo techniques. Inference metaprogramming enables the concise expression of proba- bilistic models and inference algorithms across diverse elds, such as computer vision, data science, and robotics, within a single probabilistic programming language.

Multiple traces formulation and semi-implicit scheme for modelling biological cells under electrical stimulation

We model the electrical behavior of several biological cells under external stimuli by extending and computationally improving the multiple traces formulation introduced in Henríquezet al.[Numer. Math.136(2016) 101–145]. Therein, the electric potential and current for a single cell are retrieved through the coupling of boundary integral operators and non-linear ordinary differential systems of equations. Yet, the low-order discretization scheme presented becomes impractical when accounting for interactions among multiple cells. In this note, we consider multi-cellular systems and show existence and uniqueness of the resulting non-linear evolution problem in finite time. Our main tools are analytic semigroup theory along with mapping properties of boundary integral operators in Sobolev spaces. Thanks to the smoothness of cellular shapes, solutions are highly regular at a given time. Hence, spectral spatial discretization can be employed, thereby largely reducing the number of unknowns. Time-space coupling is achievedviaa semi-implicit time-stepping scheme shown to be stable and second order convergent. Numerical results in two dimensions validate our claims and match observed biological behavior for the Hodgkin–Huxley dynamical model.

Enrichment of OpenStreetMap Data Completeness with Sidewalk Geometries Using Data Mining Techniques.

Tailored routing and navigation services utilized by wheelchair users require certain information about sidewalk geometries and their attributes to execute efficiently. Except some minor regions/cities, such detailed information is not present in current versions of crowdsourced mapping databases including OpenStreetMap. CAP4Access European project aimed to use (and enrich) OpenStreetMap for making it fit to the purpose of wheelchair routing. In this respect, this study presents a modified methodology based on data mining techniques for constructing sidewalk geometries using multiple GPS traces collected by wheelchair users during an urban travel experiment. The derived sidewalk geometries can be used to enrich OpenStreetMap to support wheelchair routing. The proposed method was applied to a case study in Heidelberg, Germany. The constructed sidewalk geometries were compared to an official reference dataset (“ground truth dataset”). The case study shows that the constructed sidewalk network overlays with 96% of the official reference dataset. Furthermore, in terms of positional accuracy, a low Root Mean Square Error (RMSE) value (0.93 m) is achieved. The article presents our discussion on the results as well as the conclusion and future research directions.

Detection and Denoising of Microseismic Events Using Time–Frequency Representation and Tensor Decomposition

Reliable detection and recovery of a microseismic event in large volume of passive monitoring data is usually a challenging task due to the low signal-to-noise ratio environment. The accuracy of weak microseismic event identification is a very important step in the analysis and interpretation of microseismic data. This paper introduces an approach for detecting (presence indication) and denoising (accurate recovery) microseismic events using tensor decomposition by considering the time-frequency representation of multiple traces as a 3-D tensor. A tensor is a multiway array having dimension greater than two, and recent signal processing techniques have been developed to manipulate such data by taking advantage of the multidimensional structure. With advances in technology and the availability of cheap memory, it is now possible to store and do mathematical operations, such as higher order singular-value decomposition or tensor decomposition, on multiway data. In active seismic, tensor decomposition has been used for multidimensional reconstruction via higher order interpolation to obtain missing observations. In this paper, we use 3-D tensor decomposition to process passive seismic data. Experiments performed on synthetic and field data sets show promising results achieved by these new methods.