Search

We give a new proof of Faltings's p-adic Eichler-Shimura decomposition of the modular curves via BGG methods and the Hodge-Tate period map. The key property is the relation between the Tate module and the Faltings extension, which was already used in the original proof. Then, we construct overconvergent Eichler-Shimura (ES) maps for the modular curves providing ''the second half'' of the overconvergent ES map of Andreatta-Iovita-Stevens. We use higher Coleman theory on the modular curve developed by Boxer-Pilloni to show that the small slope part of the ES maps interpolates the classical p-adic Eichler-Shimura decompositions. Finally, we prove that the overconvergent ES maps are compatible with Poincar\'e and Serre pairings., Comment: To appear in Compositio Mathematica

Aridoamerica and Mesoamerica are two distinct cultural areas in northern and central Mexico, respectively, that hosted numerous pre-Hispanic civilizations between 2500 BCE and 1521 CE. The division between these regions shifted southward because of severe droughts ~1100 years ago, which allegedly drove a population replacement in central Mexico by Aridoamerican peoples. In this study, we present shotgun genome-wide data from 12 individuals and 27 mitochondrial genomes from eight pre-Hispanic archaeological sites across Mexico, including two at the shifting border of Aridoamerica and Mesoamerica. We find population continuity that spans the climate change episode and a broad preservation of the genetic structure across present-day Mexico for the past 2300 years. Lastly, we identify a contribution to pre-Hispanic populations of northern and central Mexico from two ancient unsampled “ghost” populations.

Aridoamerica and Mesoamerica are two distinct cultural areas that hosted numerous pre-Hispanic civilizations between 2,500 BCE and 1,521 CE. The division between these regions shifted southward due to severe droughts ca. 1,100 years ago, allegedly driving demographic changes and population replacement in some sites in central Mexico. Here, we present shotgun genome-wide data from 12 individuals and 26 mitochondrial genomes from eight pre-Hispanic archaeological sites across Mexico, including two at the shifting border of Aridoamerica and Mesoamerica. We find population continuity spanning the climate change episode and a broad preservation of the genetic structure across present-day Mexico for the last 2,300 years. Lastly, we identify a contribution to pre-Hispanic populations of northern and central Mexico from an ancient unsampled ‘ghost’ population.

espanolEn los ultimos anos hemos observado la aparicion de un importante numero de series de television que buscan acercar al gran publico el conocimiento de nuestra historia. Productos mediaticos con gran poder de influencia en el imaginario de sus espectadores, asi como en la creacion de estereotipos. Este articulo pretende reflexionar en torno al papel que los productos televisivos de pretendido caracter historico pueden jugar en el conocimiento de la gente, asi como sobre la utilidad de este modo de aproximacion al conocimiento historico. EnglishOver the past years, We have observed the appearance of a significant number of television series that seek to bring the general public closer to the knowledge of our history. Media products with high power to influence the imagery of their viewers, as well as the creation of stereotypes. This article proposes to reflect on the role that television products of the intended historical character can play in the knowledge of people as well as on the utility of this approach to historical knowledge.

The population of Mexico has a considerable genetic substructure due to both its pre-Columbian diversity and due to genetic admixture from post-Columbian trans-oceanic migrations. The latter primarily originated in Europe and Africa, but also, to a lesser extent, in Asia. We analyze previously understudied genetic connections between Asia and Mexico to infer the timing and source of this genetic ancestry in Mexico. We identify the predominant origin within Southeast Asia—specifically western Indonesian and non-Negrito Filipino sources—and we date its arrival in Mexico to approximately 13 generations ago (1620 CE). This points to a genetic legacy from the seventeenth century Manila galleon trade between the colonial Spanish Philippines and the Pacific port of Acapulco. Indeed, within Mexico we observe the highest level of this trans-Pacific ancestry in Acapulco, located in the state of Guerrero. This colonial Spanish trade route from East Asia to Europe was centred on Mexico and appears in historical records, but its legacy has been largely ignored. Identities and stories were suppressed due to slavery, assimilation of the immigrants as ‘Indios’ and incomplete historical records. Here we characterize this understudied Mexican ancestry. This article is part of the theme issue ‘Celebrating 50 years since Lewontin's apportionment of human diversity’.

SummaryMexico has considerable population substructure due to pre-Columbian diversity and subsequent variation in admixture levels from trans-oceanic migrations, primarily from Europe and Africa, but also, to a lesser extent, from Asia. Detailed analyses exploring sub-continental structure remain limited and post-Columbian demographic dynamics within Mexico have not been inferred with genomic data. We analyze the distribution of ancestry tracts to infer the timing and number of pulses of admixture in ten regions across Mexico, observing older admixture timings in the first colonial cities and more recent timings moving outward into southern and southeastern Mexico. We characterize the specific origin of the heterogeneous Native American ancestry in Mexico: a widespread western-central Native Mesoamerican component in northern Aridoamerican states and a central-eastern Nahua contribution in Guerrero (southern Mexico) and Veracruz to its north. Yucatan shows lowland Mayan ancestry, while Sonora exhibits a unique northwestern native Mexican ancestry matching no sampled reference, each consistent with localized indigenous cultures. Finally, in Acapulco, Guerrero a notable proportion of East Asian ancestry was observed, an understudied heritage in Mexico. We identified the source of this ancestry within Southeast Asia—specifically western Indonesian and non-Negrito Filipino—and dated its arrival to approximately thirteen generations ago (1620 CE). This points to a genetic legacy from the 17thcentury Manila Galleon trade between the colonial Spanish Philippines and the Pacific port of Acapulco in Spanish Mexico. Although this piece of the colonial Spanish trade route from China to Europe appears in historical records, it has been largely ignored as a source of genetic ancestry in Mexico, neglected due to slavery, assimilation as “Indios” and incomplete historical records.

Polynesia was settled in a series of extraordinary voyages across an ocean spanning one third of the Earth1, but the sequences of islands settled remain unknown and their timings disputed. Currently, several centuries separate the dates suggested by different archaeological surveys2–4. Here, using genome-wide data from merely 430 modern individuals from 21 key Pacific island populations and novel ancestry-specific computational analyses, we unravel the detailed genetic history of this vast, dispersed island network. Our reconstruction of the branching Polynesian migration sequence reveals a serial founder expansion, characterized by directional loss of variants, that originated in Samoa and spread first through the Cook Islands (Rarotonga), then to the Society (Tōtaiete mā) Islands (11th century), the western Austral (Tuha’a Pae) Islands and Tuāmotu Archipelago (12th century), and finally to the widely separated, but genetically connected, megalithic statue-building cultures of the Marquesas (Te Henua ‘Enana) Islands in the north, Raivavae in the south, and Easter Island (Rapa Nui), the easternmost of the Polynesian islands, settled in approximately ad 1200 via Mangareva. Analysis of genomic networks from 430 modern individuals across 21 Pacific island populations reveals the human settlement history of Polynesia.

Traditional Probabilistic Seismic Hazard Analysis (PSHA) estimates the level of earthquake ground shaking that is expected to be exceeded with a given recurrence time on the basis of historical earthquake catalogues and empirical and time-independent Ground Motion Prediction Equations (GMPEs). The smooth nature of GMPEs usually disregards some well known drivers of ground motion characteristics associated with fault rupture processes, in particular in the near-fault region, complex source-site propagation of seismic waves, and sedimentary basin response. Modern physics-based earthquake simulations can consider all these effects, but require a large set of input parameters for which constraints may often be scarce. However, with the aid of high-performance computing (HPC) infrastructures the parameter space may be sampled in an efficient and scalable manner allowing for a large suite of site-specific ground motion simulations that approach the center, body and range of expected ground motions. CyberShake is a HPC platform designed to undertake physics-based PSHA from a large suite of earthquake simulations. These simulations are based on seismic reciprocity, rendering PSHA computationally tractable for hundreds of thousands potential earthquakes. For each site of interest, multiple kinematic rupture scenarios, derived by varying slip distributions and hypocenter location across the pre-defined fault system, are generated from an input Earthquake Forecast Model (EFM). Each event is simulated to determine ground motion intensities, which are synthesized into hazard results. CyberShake has been developed by the Southern California Earthquake Center, and used so far to assess seismic hazard in California. This work focuses on the CyberShake migration to the seismic region of South Iceland (63.5°- 64.5°N, 20°-22°W) where the largely sinistral East-West transform motion across the tectonic margin is taken up by a complex array of near-vertical and parallel North-South oriented dextral transform faults in the South Iceland Seismic Zone (SISZ) and the Reykjanes Peninsula Oblique Rift (RPOR). Here, we describe the main steps of migrating CyberShake to the SISZ and RPOR, starting by setting up a relational input database describing potential causative faults and rupture characteristics, and key sites of interest. To simulate our EFM, we use the open source code SHERIFS, a logic-tree method that converts the slip rates of complex fault systems to the corresponding annual seismicity rate. The fault slip rates are taken from a new 3D physics-based fault model for the SISZ-RPOR transform fault system. To validate model and simulation parameters, two validation steps using key CyberShake modeling tools have been carried out. First, we perform simulations of historical earthquakes and compare the synthetics with recorded ground motions and results from other forward simulations. Second, we adjust the rupture kinematics to make slip distributions more representative of SISZ-type earthquakes by comparing with static slip distributions of past significant earthquakes. Finally, we run CyberShake and compare key parameters of the synthetic ground motions with new GMPEs available for the study region. The successful migration and use of CyberShake in South Iceland is the first step of a full-scale physics-based PSHA in the region, and showcases the implementation of CyberShake in new regions.

Seismic wave propagation is currently computationally prohibitive at high frequencies relevant for earthquake engineering or for civil protection purposes (up to 10 Hz). Developments of computational high-performance computing (HPC) infrastructures, however, will render routine executions of high-frequency simulations possible, enabling new approaches to assess seismic hazard - such as Seismic Urgent Computing (UC) in the immediate aftermath of an earthquake. The high spatial resolution of near-real time synthetic wavefields could complement existing live data records where dense seismic networks are present or provide an alternative to live data in regions with low coverage. However, time to solution for local near-field simulations accounting for frequencies above 1 Hz, as well as availability of substantial computational resources pose significant challenges that are incompatible with the requirements of decision makers. Moreover, the simulations require fine tuning of the parameters, as uncertainties in the underlying velocity model and in earthquake source information translate into uncertainties in final results. Estimating such uncertainties on ground motion proxies is non-trivial from a scientific standpoint, especially for the higher frequencies that remain an uncharted territory. In this talk we wish to address some of these key challenges and present our progress in the design and development of a prototype of a Seismic UC service. In the long run, we hope to demonstrate that deterministic modelling of ground motions can indeed in the future contribute to the short-term assessment of seismic hazard.

We construct an integral model of the perfectoid modular curve. Studying this object, we prove some vanishing results for the coherent cohomology at perfectoid level. We use a local duality theorem at finite level to compute duals for the coherent cohomology of the integral perfectoid curve. Specializing to the structural sheaf, we can describe the dual of the completed cohomology as the inverse limit of the integral cusp forms of weight $2$ and trace maps., 31 pages

The possibility of voyaging contact between prehistoric Polynesian and Native American populations has long intrigued researchers. Proponents have pointed to the existence of New World crops, such as the sweet potato and bottle gourd, in the Polynesian archaeological record, but nowhere else outside the pre-Columbian Americas1–6, while critics have argued that these botanical dispersals need not have been human mediated7. The Norwegian explorer Thor Heyerdahl controversially suggested that prehistoric South American populations had an important role in the settlement of east Polynesia and particularly of Easter Island (Rapa Nui)2. Several limited molecular genetic studies have reached opposing conclusions, and the possibility continues to be as hotly contested today as it was when first suggested8–12. Here we analyse genome-wide variation in individuals from islands across Polynesia for signs of Native American admixture, analysing 807 individuals from 17 island populations and 15 Pacific coast Native American groups. We find conclusive evidence for prehistoric contact of Polynesian individuals with Native American individuals (around ad 1200) contemporaneous with the settlement of remote Oceania13–15. Our analyses suggest strongly that a single contact event occurred in eastern Polynesia, before the settlement of Rapa Nui, between Polynesian individuals and a Native American group most closely related to the indigenous inhabitants of present-day Colombia. Genomic analyses of DNA from modern individuals show that, about 800 years ago, pre-European contact occurred between Polynesian individuals and Native American individuals from near present-day Colombia, while remote Pacific islands were still being settled.

Earthquake and tsunami early warning systems and post-event urgent computing simulations require of fast and accurate quantification of earthquake parameters such as magnitude, location and Focal Mechanism (FM). Methodologies to estimate earthquake location and magnitude are well-established and in place. However, automatic solutions of FMs are not always provided by operational institutions and are, in some cases, available only after a time-consuming inversion of the wave-forms needed to determine the moment tensor components. This precludes urgent seismic simulations, which aim at providing ground shaking maps with severe time constraints. We propose a new strategy for fast (

The invasion of Poland marked the beginning of the horror of World War II. After the concessions made to Hitler in Czechoslovakia, both France and England couldn’t simply look the other way when Hitler violated the polish border. This is a subject, then, of capital historical relevance and it’s teaching in class fundamental. This article remarks the didactical resources for it’s better explaining through the use of literary texts that help students to complete their vision of the analyzed facts. The intersected and close connection between History and Literature stands once more vindicated.

Deadly earthquakes are events that are unpredictable, relatively rare and have a huge impact upon the lives of those who suffer their consequences. Furthermore, each earthquake has specific characteristics (location, magnitude, directivity) which, combined to local amplification and de-amplification effects, makes their outcome very singular. Empirical relations are the main methodology used to make early assessment of an earthquake's impact. Nevertheless, the lack of sufficient data registers for large events makes such approaches very imprecise. Physics-based simulators, on the other hand, are powerful tools that provide highly accurate shaking information. However, physical simulations require considerable computational resources, a detailed geological model, and accurate earthquake source information. A better early assessment of the impact of earthquakes implies both technical and scientific challenges. We propose a novel HPC-based urgent seismic simulation workflow, hereafter referred to as Urgent Computing Integrated Services for EarthQuakes (UCIS4EQ), which can deliver, potentially, much more accurate short-time reports of the consequences of moderate to large earthquakes. UCIS4EQ is composed of four subsystems that are deployed as services and connected by means of a workflow manager. This paper describes those components and their functionality. The main objective of UCIS4EQ is to produce ground-shaking maps and other potentially useful information to civil protection agencies. The first demonstrator will be deployed in the framework of the Center of Excellence for Exascale in Solid Earth (ChEESE, https://cheese.coe.eu/, last access: 12 Feb. 2020). The ChEESE project has received funding from the European Union’sHorizon 2020 research and innovation programme under the grantagreement Number 823844. Further funding includes the SpanishMinistry project GAP TIN2016-80957-P, the EU project MATH-ROCKS Number 777778. The Graves-Pitarka Generator is availablethrough the SCEC Broadband Platform version 19.4. We acknowl-edge the assistance by Favio Silva and Phillip Maechling on itscompilation and execution.

Full waveform inversion (FWI) is one of the most challenging procedures to obtain quantitative information of the subsurface. For elastic inversions, when both compressional and shear velocities have to be inverted, the algorithmic issue becomes also a computational challenge due to the high cost related to modelling elastic rather than acoustic waves. This shortcoming has been moderately mitigated by using high-performance computing to accelerate 3D elastic FWI kernels. Nevertheless, there is room in the FWI workflows for obtaining large speedups at the cost of proper grid pre-processing and data decimation techniques. In the present work, we show how by making full use of frequency-adapted grids, composite shot lists and a novel dynamic offset control strategy, we can reduce by several orders of magnitude the compute time while improving the convergence of the method in the studied cases, regardless of the forward and adjoint compute kernels used.

Native American genetic variation remains underrepresented in most catalogs of human genome sequencing data. Previous genotyping efforts have revealed that Mexico’s indigenous population is highly differentiated and substructured, thus potentially harboring higher proportions of private genetic variants of functional and biomedical relevance. Here we have targeted the coding fraction of the genome and characterized its full site frequency spectrum by sequencing 76 exomes from five indigenous populations across Mexico. Using diffusion approximations, we modeled the demographic history of indigenous populations from Mexico with northern and southern ethnic groups splitting 7.2 kya and subsequently diverging locally 6.5 kya and 5.7 kya, respectively. Selection scans for positive selection revealed BCL2L13 and KBTBD8 genes as potential candidates for adaptive evolution in Rarámuris and Triquis, respectively. BCL2L13 is highly expressed in skeletal muscle and could be related to physical endurance, a well-known phenotype of the northern Mexico Rarámuri. The KBTBD8 gene has been associated with idiopathic short stature and we found it to be highly differentiated in Triqui, a southern indigenous group from Oaxaca whose height is extremely low compared to other native populations.

How did the political figures of the 70s and 80s influenced the way in which the history of Portuguese and Spanish colonial empires was told? That is the main question this article intends to answer. History manuals can stigmatize a period or evoke for eternity the figure of a determined monarch or politician. From the assumption that the textbook has been the educational resource most used to the development of the study of History, it’s interesting to analyse the way in which these books presented to Portuguese and Spanish students both the history and the characters of their colonial empires. For that purpose this article examines the main set of books shared in the Iberian Peninsula during the 70s and 80s with the intention of reflecting on the connection between their historical contents and the distinct political scenarios in Spain and Portugal. The selected books belong to the 2nd cycle of secondary education (in the case of New State), corresponding after the 3rd cycle of basic education (Democratic period) in the case of Portugal and also to the General Basic Education in Spain.

The so-called «Battle of Britain» is one of the key episodes of the Second World War due to the fact that it marks the first time that Hitler’s ambitions were slowed down in a severe way. Churchill’s resistance, and with him England’s, means the first stone of a building made of nations facing the III Reich. It is therefore a deeply significant issue to take into the classroom, and for structuring didactic strategies to help with its understanding. At this point, Literature is shown as an unbeatable area for supporting History. We should reach it, we have the possibility to take advantage from great quality literary texts which deal with these matters to illustrate historical explanations. That is the purpose of this article, to reflect about the relationship between History and Literature, to explain the «Battle of Britain» and to illustrate it providing literary texts that help us understand the situations and events in question.

Full-waveform inversion (FWI) in seismic scenarios continues to be a complex procedure for subsurface imaging that might require extensive human interaction in terms of model setup, constraints, and data preconditioning. The underlying reason is the strong nonlinearity of the problem that forces the addition of a priori knowledge (or bias) in order to obtain geologically sound results. In particular, when the use of a long-offset receiver is not possible or may not favor the reconstruction of the fine structure of the model, one needs to rely on reflection data. As a consequence, the inversion process is more prone to becoming stuck in local minima. Nevertheless, misfit functionals can be devised that can either cope with missing long-wavenumber features of initial models (e.g., cross-correlation-based misfit) or invert reflection-dominated data whenever the models are sufficiently good (e.g., normalized offset-limited least-squares misfit). By combining both, high-frequency data content with poor initial models can be successfully inverted. If one can figure out simple parameterizations for such functionals, the amount of uncertainty and manual work related to tuning FWI would be substantially reduced. Thus, FWI might become a semiautomatized imaging tool. We want to thank Repsol for funding this research by means of the Aurora project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 644202. Additionally, the research leading to these results has received funding from the European Union’s Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP) under the HPC4E Project (www.hpc4e.eu), grant agreement No 689772. We acknowledge Chevron for the dataset that was used in our second example.

Wide azimuth seismic surveys are needed in areas where conventional narrow azimuth streamer seismic data is insufficient for cost effective field development. Wide azimuth surveys are required in areas with illumination challenges or/and critical anisotropy or/and fracturing systems. Carbonate reservoirs may have a rapid spatial variation of their rock properties and lateral structural heterogeneities. They are difficult to characterize and have associated a high risk in structural interpretation. Objective of seismic data acquisition is not only to reduce the uncertainty of the final structural model but as well to determine the properties of the complex carbonate reservoir such as fracturing systems and their spatial distribution. Ray Tracing Modeling showed that there were not illumination issues. Anisotropy with associated velocity field changes on direction will cause small changes in the travel times to horizons. If the anisotropic effects are not considered, structural image may be degraded or there will be uncertainty in the position of the structural evens. However, the changes in travel times only will produce small variations in total illumination.

Los manuales de Historia influyen en el imaginario individual del alumno, asi como en la creacion de una memoria colectiva y de unos estereotipos culturales. Del mismo modo, pueden contribuir a estigmatizar una epoca o a un personaje historico, o bien a ensalzar para siempre la figura de un determinado monarca o grupo social. El libro de texto ha sido el recurso didactico mas utilizado para el desarrollo de la asignatura de Historia. Las distintas perspectivas de su analisis han propiciado una interesante linea de investigacion en Didactica de la Historia. Por ello, resulta muy interesante prestar atencion a la manera en que estos libros han presentado a nuestros escolares la historia, hechos y personajes de la Guerra de la Independencia, al ser esta uno de los procesos historicos mas utilizados en la creacion y consolidacion de identidades colectivas en Espana. Para obtener una muestra significativa en nuestro estudio, utilizamos ejemplos de las editoriales mas representativas y acudimos a textos de Educacion Secundaria editados en distintos momentos de las ultimas cuatro decadas.

Full Waveform Inversion of elastic dataset is challenging due to the complexity introduced by free-surface effects or P-S waves conversions among others. In this context, large offset are prefered for inversion because they favour transmission modes which are more linearly related to P-wave velocity. In contrast, the problem addressed here is whether short offset inversion should be suitable for seismic imaging. To answer this question, we choose to invert an elastic dataset obtained from the SEG/Overthrust SEG/EAGE model, with simultaneous inversion of Lame parameters. We will show that by using short offset and with only minimal pre-processing of the data (e.g. low-pass filter), we are able to construct reliable gradients. This, in turns, leads to accurate inversion of both shear and compression velocity models.

Parallel computer systems for geophysical electromagnetic modeling and inversion problems have been developed rapidly in the past decade addressing the needs of the industrial applications. In this work we present electromagnetics in BSIT, a software framework developed for massively parallel distributed environments. Its flexible structure allows to combine different physical problems with various solution methods and computer architectures. Inversion and forward modeling can be performed on independent grids with a proper interpolation scheme. For the EM modeling, kernels for isotropic and transversely isotropic media have been developed. The simulations show high efficiency and scalability of the code. Joint inversion of EM and other types of geophysical data could be performed in the future.

Full Waveform Inversion is one of the most advanced processing methods that is recently reaching a mature state after years of solving theoretical and technical issues such as the non-uniqueness of the solution and harnessing the huge computational power required by realistic scenarios. In this work, we present the application of this method to a 3D on-land dataset acquired to characterize the shallow subsurface. The current study explores the possibility to apply elastic isotropic Full Waveform Inversion using only the vertical component of the recorded seismograms. One of the main challenges in this case study remains the costly 3D modeling that includes topography and free surface effects. Nevertheless, the resulting models provide a higher resolution of the subsurface structures than starting models, and show a good correlation with the available borehole measurements. The authors thank Repsol for the permission to publish the present research and for funding through the Aurora project. J. Kormann also thankfully acknowledges the Spanish Supercomputing Network (RES) through grant FI-2014-2-0009. Funding support for the data acquisition and access to the available geophysical data was provided by ENRESA. The GFZ Instrument Pool provided the instrumentation for the data acquisition. This project was partially funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 644602.

Full Waveform Inversion of elastic dataset is challenging due to the complexity introduced by free-surface effects or P-S wave conversions among others. In this context, large offsets are preferred for inversion because they favor transmission modes which are more linearly related to P-wave velocity. In this paper, we present an original approach which allows to dynamically select the near offset at each frequency. We illustrate this approach with the inversion of a dataset without density. In order to deal with a more realistic scenario, we next present the inversion with density effects included into the modeling. As inverting density is known to be a hard task, we choose to not invert it. This approach leads to the use of a phase misfit function, which is more connected to the kinematics of the problem than the classic L2 norm. The authors want to thank Repsol for the permission to publish the present research, carried out at the Repsol-BSC Research Center. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk lodowska-Curie grant agreement No 644202.

Traditionally, most of the literature in seismic processing area is devoted to proposals regarding the physics and numerical methods used for solving the underlying problem, such as: modellings, migrations, inversions, etc. There are, however, a lot of effort placed in the infrastructure needed to manage the processing carried out by such systems, as a lot of parallelism, fault tolerance, interaction, etc, is needed to actually produce a result. The aim of this work is to propose a framework, based on the Agile Modelling principle. Such framework, will let the developer create a modelling, migration or inversion process (among others), taking care of the topics that normally falls outside of the scope of seismic processing contributions.

Full Waveform Inversion (FWI) is a geophysical tool that is designed to improve subsurface models by directly comparing, by means of a misfit function, synthetic traces obtained using an initial model with the real trace recorded experimentally. However, the high computational cost of the forward modeling combined with the huge size of the data, make FWI an extremely complex HPC problem. Nevertheless, its enhanced resolution compared to other seismic inversion methods is starting to make FWI an attractive subsurface imaging tool for both industry and academy. An FWI system workflow consists in processing the data (e.g filtering, windowing), launching gradi- ent computation simulations for each shot, merging the gradients, launching an optimization algorithm which involves executing modeling simulations and finally, updating the models with the merged gradients. On top of that, this is performed inside a minimization loop which is nested inside a frequency selection loop. This leads to complex interactions between nodes and therefore requires an extremely robust environment to be successful, in particular for large 3D inversions. Thus there is a challenge in terms of computational cost, but also of development cost, in order to obtain an FWI system which produces inverted models both reliably and efficiently.

Full Waveform Inversion is an ill-posed problem. As such, it needs mathematical and numerical tools to improve convergence and avoid falling into local minima. This is a crucial issue, especially when using bad starting models for inversion. The question addressed here is whether Full Waveform Inversion should be suitable for seismic imaging. To answer this problem, we simulate a simple seismic experiment that consists in two square velocity anomalies surrounded by a homogeneous medium. The difficulty here results in the homogeneous starting model used for inversion and the acquisition design that is not suitable for inverting this kind of features. Because the physical problem shows mostly reflective behaviour, retrieving model parameters is very challenging. Nevertheless, we will show that the preconditioner presented in this work allows us to recover accurately both position and velocity values of the reservoirs, leading to very precise images of both anomalies after applying Reverse Time Migration.

Direct application of toluidine blue dye to the gastric mucosa under immediate endoscopic observation has enhanced the delineation of intestinal metaplasia and aided in the differential diagnosis of benign and malignant gastric ulceration.