2,782 research outputs found

    Imaging Seismic Reflections

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    The goal of reflection seismic imaging is making images of the Earth subsurface using surface measurements of reflected seismic waves. Besides the position and orientation of subsurface reflecting interfaces it is a challenge to recover the size or amplitude of the discontinuities. We investigate two methods or techniques of reflection seismic imaging in order to improve the amplitude. First we study the \textsl{one-way wave equation} with attention to the amplitude of the waves. In our study of \textsl{reverse-time migration} the amplitude refers to the amplitude of the image. Though the approach in the thesis is formal, our results have practical implications for seismic imaging algorithms, which improve or correct the amplitudes. The one-way wave equation is a 1st1^{\rm st}-order equation that describes wave propagation in a predetermined direction. We derive the equation and identify the steps that determine the wave amplitude. We introduce a \textsl{symmetric square root operator} and a wave field normalization operator and show that they provide the correct amplitude. The idea to use a symmetric square root is generally applicable. Our amplitude claims are numerically verified. The one-way wave equation is an application of \textsl{pseudo-differential operators}. \textsl{Reverse-time migration} (RTM) is an imaging method that uses simulations of the source and receiver wave fields through a slowly varying estimate of the subsurface medium. The receiver wave is an in reverse time continued field that matches the measurements. An \textsl{imaging condition} transforms the fields into an image of the small scale medium contrast. We investigate the linearized inverse problem and use the RTM procedure to reconstruct the perturbation of the medium. We model the scattering event by the scattering operator, which maps the medium perturbation to the scattered wave. We propose an approximate inverse of the scattering operator, derive a novel imaging condition and show that it yields a reconstruction of the perturbation with correct amplitude. The study extensively uses the theory of \textsl{Fourier integral operators} (FIO). Besides that we globally characterize the scattering operator as a FIO, we also obtain a local expression to calculate the amplitude explicitly. The claims are confirmed and illustrated by numerical simulations

    Magnetic read only memory

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    #MeToo & the Courts: The Impact of Social Movements on Federal Judicial Decisionmaking

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    In late 2017, the #MeToo movement swept through the United States as individuals from all backgrounds and walks of life revealed their experiences with sexual abuse and sexual harassment. After the #MeToo movement, many scholars, advocates, and policymakers posited that the watershed moment would prompt changes in the ways in which sexual harassment cases were handled. This Article examines the impact the #MeToo movement has had on judicial decisionmaking. Our hypothesis is that the #MeToo movement’s increase in public awareness and political attention to experiences of sexual misconduct should lead to more pro-claimant voting in federal courts at the district and courts of appeals levels. For district courts, we find that the probability of a pro-employee ruling in a district court increased drastically after November 1, 2017. However, while pro-employee rulings increased in district courts during the #MeToo era, pro-employee rulings decreased in circuit courts during this time period. Our findings suggest that the #MeToo movement—an extralegal social movement—impacted legal rulings that occurred in its wake before district courts but courts of appeals were more restrained in their reaction to the movement. Importantly, the law and legal standards in place during the time period of our study did not meaningfully change. In short, the #MeToo movement had a statistically significant impact on rulings from district court judges

    A Novel Isoflurane Anesthesia Induction System for Raccoons

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    We developed a novel small-volume (24-L) conical-shaped isoflurane anesthesia induction chamber for use in a den chamber and tested it along with 3 conventional stand-alone induction chambers (2 clear acrylic plastic chambers and a cylindrical-shaped chamber) to determine utility for daily short-duration manipulations of captive raccoons (Procyon lotor). Although the conventional chambers were valuable, the majority of inductions were performed using the cone chamber in a pen setting. With the novel device, we were able to minimize the need for pre-anesthetic handling of animals and eliminate the need for injectable anesthesia agents. As a result, side effects normally associated with injectable agents were avoided. Mean anesthesia induction time using the cone chamber was 3.4 min (SD = 0.90). When used as designed, conventional chambers worked well, with induction times ranging from 2.7 min to 5.4 min. Because the stand-alone chambers were not reliant upon den chambers for use, they may provide greater utility for field work. The conical-shaped induction chamber, however, provides an option for safe short-duration anesthetization of captive raccoons and could perhaps be used with other species and in other research settings

    #MeToo & The Courts: The Impact of Social Movements on Federal Judicial Decisionmaking

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    In late 2017, the #MeToo movement swept through the United States as individuals from all backgrounds and walks of life revealed their experiences with sexual abuse and sexual harassment. After the #MeToo movement, many scholars, advocates, and policymakers posited that the watershed moment would prompt changes in the ways in which sexual harassment cases were handled. This Article examines the impact the #MeToo movement has had on judicial decisionmaking. Our hypothesis is that the #MeToo movement’s increase in public awareness and political attention to experiences of sexual misconduct should lead to more pro-claimant voting in federal courts at the district and courts of appeals levels. For district courts, we find that the probability of a pro-employee ruling in a district court increased drastically after November 1, 2017. However, while pro-employee rulings increased in district courts during the #MeToo era, pro-employee rulings decreased in circuit courts during this time period. Our findings suggest that the #MeToo movement—an extralegal social movement—impacted legal rulings that occurred in its wake before district courts but courts of appeals were more restrained in their reaction to the movement. Importantly, the law and legal standards in place during the time period of our study did not meaningfully change. In short, the #MeToo movement had a statistically significant impact on rulings from district court judges

    The C@merata Task at MediaEval 2014: Natural Language Queries on Classical Music Scores

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    This paper summarises the C@merata task in which participants built systems to answer short natural language queries about classical music scores in MusicXML. The task thus combined natural language processing with music information retrieval. Five groups from four countries submitted eight runs. The best submission scored Beat Precision 0.713 and Beat Recall 0.904

    Comment on studying the corrections to factorization in B -> D(*) X

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    We propose studying the mechanism of factorization in exclusive decays of the form B->D(*)X by examining the differential decay rate as a function of the invariant mass of the light hadronic state X. If factorization works primarily due to the large N_c limit then its accuracy is not expected to decrease as the X invariant mass increases. However, if factorization is mostly a consequence of perturbative QCD then the corrections should grow with the X invariant mass. Combining data for hadronic tau decays and semileptonic B decays allows tests of factorization to be made for a variety of final states. We discuss the examples of B->D^*\pi^+\pi^-\pi^-\pi^0 and B->D^*\omega\pi^-. The mode B->D^*\omega\pi^- will allow a precision study of the dependence of the corrections to factorization on the invariant mass of the light hadronic state.Comment: 7 pages, minor clarifications to tex

    Centering Individual Animals to Improve Research and Citation Practices

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    Modern behavioural scientists have come to acknowledge that individual animals may respond differently to the same stimuli and that the quality of welfare and lived experience can affect behavioural responses. However, much of the foundational research in behavioural science lacked awareness of the effect of both welfare and individuality on data, bringing their results into question. This oversight is rarely addressed when citing seminal works as their findings are considered crucial to our understanding of animal behaviour. Furthermore, more recent research may reflect this lack of awareness by replication of earlier methods – exacerbating the problem. The purpose of this review is threefold. First, we critique seminal papers in animal behaviour as a model for re-examining past experiments, attending to gaps in knowledge or concern about how welfare may have affected results. Second, we propose a means to cite past and future research in a way that is transparent and conscious of the abovementioned problems. Third, we propose a method of transparent reporting for future behaviour research that (i) improves replicability, (ii) accounts for individuality of non-human participants, and (iii) considers the impact of the animals\u27 welfare on the validity of the science. With this combined approach, we aim both to advance the conversation surrounding behaviour scholarship while also serving to drive open engagement in future science
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