The landing sites of the landers of Apollo 11, 12, 14, 15, 16, and 17 as well as Luna 16, 20, and 23 spacecraft are all located within specific phase-ratio anomalies caused by the engine jets. The ...landing site identified as that of the Luna 24 spacecraft, however, was not located within its corresponding anomaly, leading Shkuratov et al. (2013) to suggest that this may be due to the misidentification of the Luna 23 and 24 spacecraft in the LROC images, since the Luna 23 landing was not successful. Dolgopolov et al. (2013) synthesized images of the Luna spacecraft as they might appear in the LROC images, using a model made by the Lavochkin Association. They found similarity of the spacecraft seen in the LROC images with the synthetic images corresponding to successful and unsuccessful missions and concluded that the original identification of the Luna 23 and 24 spacecraft in the images by Robinson et al. (2012) is likely correct. However, Dolgopolov et al. (2013) used only one illumination geometry for each landing site. As distinct from Dolgopolov et al. (2013) we make a similar analysis using a 3D computer spacecraft model using several different illuminations of the spacecraft and show that the orientations used by Dolgopolov are inconsistent with other LROC images, and it is impossible to make a reliable conclusion based on these analyses. We also show that geologic arguments presented by Dolgopolov et al. (2013) are ambiguous. Using Lucey et al.’s (1995) technique and multispectral images acquired with the Kaguya MI camera (resolution ~20m), we show that small areas around the landing sites of the probes have almost the same contents of FeO and TiO2, as well as fairly close maturity degree of the regolith.
•The anomalous phase-ratio image of the Luna 24 landing site suggests misidentification.•Analysis of Luna 23 and 24 computer models does not confirm the original identification.•We found noticeable inconsistencies with results by Dolgopolov et al. (2013).•Geological arguments and multispectral analyses also are ambiguous for identification.
•DRFTIR parameters distinguish organic facies in kerogen from La Luna Fm.•DRFTIR parameters distinguish thermal maturity in kerogen from La Luna Fm.•DRFTIR parameters have been applied on marine type ...II kerogen for first time.•A new calculation of uncertainty of DRFTIR parameters has been proposed.•An aliphaticity DRFTIR parameter AII has been proposed for kerogen type II.
Twelve samples of marine type II kerogen from La Luna Formation (Maracaibo sub-Basin, Western Venezuelan Basin) have been characterized via diffuse reflectance – Fourier-transform – infrared spectroscopy (DRFTIR). The samples were selected from different regions in the sub-Basin and correspond to different maturity levels with subtle variations in organic facies. For the analysis, the kerogen samples were mixed with potassium bromide (KBr) at a 5% w/w concentration. Spectra were obtained using a Varian 640-IR spectrometer operating in Fourier Transform mode and coupled with an EasiDiff diffuse reflectance accessory. Each spectrum was generated within the 400–4000 cm−1 frequency interval, at 4 cm−1 resolution, after 52 scans. IR parameters known to distinguish organic facies, such as the A factor and the C factor, separated the kerogen from anoxic environment (samples from the Maraca Creek) versus the kerogen from suboxic/disoxic conditions (samples from La Molina and San Antonio). Organic facies indices by Chen et al. (1998) showed to be influenced by maturity effects. Higher thermal maturity of samples from La Molina creek was supported by increasing aromaticity (indices by Lis et al., 2005), as well as decreasing aliphaticity as expressed by a new parameter termed here in as AII. This parameter compares aromatic signals in the 700–900 cm−1 interval with the aliphatic bands centered at 2953, 2923, and 2856 cm−1. This is the first study that applies DRFTIR compositional parameters to characterize kerogen type II from marine carbonates.
Flow diversion has become a well-accepted option for the treatment of cerebral aneurysms. Given the significant treatment effect of flow diverters, numerous options have emerged since the initial ...Pipeline embolization device studies. In this review, the authors describe the available flow diverters, both endoluminal and intrasaccular, addressing nuances of device design and function and presenting data on complications and outcomes, where available. They also discuss possible future directions of flow diversion.
Rufino Tamayo Rebollar Vergara, Luis
Designio, Investigación en Diseño Gráfico y Estudios de la Imagen,
04/2021, Letnik:
3, Številka:
1
Journal Article
Recenzirano
Odprti dostop
El objetivo del presente artículo es analizar el mural Dualidad del pintor oaxaqueño Rufino Tamayo. La finalidad consiste en la elaboración de una ficha de obra que contenga la descripción de los ...elementos del mural; con base en fuentes historiográficas, el contexto histórico, social y cultural en que se creó y la técnica empleada por el artista.
La Didáctica de la Astronomía es una especialidad aún joven, a pesar de unos cuarenta años de desarrollo en el mundo y poco menos en Latinoamérica. Aunque consolidada, tiene todavía mucha ...potencialidad por desarrollar para profundizar y mejorar las acciones que hemos ido concretado hasta el presente. Podríamos indicar dos grandes inconvenientes para que tal potencialidad se manifieste en las aulas con experiencias creativas y de calidad. El primero, quizás el más importante y urgente a resolver, es la falta de jóvenes educadores e investigadores formados en esta especialidad, aquello de la “masa crítica” necesaria para que una comunidad científica funcione adecuadamente. El segundo inconveniente, vinculado sin dudas al primero, es la falta de una “memoria didáctica”: un corpus de experiencias, materiales, recursos, reales y probados, disponibles libremente para quienes quieran acceder a ellos, para replicarlos y transformarlos. Presentamos algunas reflexiones y propuestas concretas sobre el segundo de los inconvenientes antes citados, en especial con el fin de mostrar una manera posible, valiosa según nuestra experiencia, para el desarrollo de acciones didácticas novedosas. Para el diseño de las mismas se han tomado en cuenta los conceptos de espacio y tiempo y su vinculación con los aspectos observacionales de la Didáctica de la Astronomía, los fundamentos epistemológicos como el mecanismo lógico hipotético-deductivo en la actividad experimental, la capacidad de tomar decisiones creativas en el proceso de contrastación entre el modelo y la realidad bajo estudio, y la dimensión vivencial de las acciones didácticas vinculadas al cielo. Las propuestas concretas son dos: deducir la posición del Sol en el cielo a partir de una fotografía de la sombra de nubes tomada desde un avión, y deducir la fase de la Luna a partir de una fotografía de una luminaria esférica blanca. Las propuestas presentadas han sido probadas en aulas reales durante años.
Magnesium‐rich spinel assemblages occur in the two lunar vitric breccia meteorites—Dhofar (Dho) 1528 and Graves Nunataks (GRA) 06157. Dho 1528 contains up to ~0.7 mm cumulate Mg‐rich spinel crystals ...associated with Mg‐rich olivine, Mg‐ and Al‐rich pyroxene, plagioclase, and rare cordierite. Using thermodynamic calculations of these mineral assemblages, we constrain equilibration depths and discuss an origin of these lithologies in the upper mantle of the Moon. In contrast, small, 10 to 20 μm spinel phenocryst assemblages in glassy melt rock clasts in Dho 1528 and GRA 06157 formed from the impact melting of Mg‐rich rocks. Some of these spinel phenocrysts match compositional constraints for spinel associated with “pink spinel anorthosites” inferred from remote sensing data. However, such spinel phenocrysts in meteorites and Apollo samples are typically associated with significant amounts of olivine ± pyroxene that exceed the compositional constraints for pink spinel anorthosites. We conclude that the remotely sensed “pink spinel anorthosites” have not been observed in the collections of lunar rocks. Moreover, we discuss impact‐excavation scenarios for the spinel‐bearing assemblages in Dhofar 1528 and compare the bulk rock composition of Dho 1528 to strikingly similar compositions of Luna 20 samples that contain ejecta from the Crisium impact basin.
In medical-data driven learning, 3D convolutional neural networks (CNNs) have started to show superior performance to 2D CNNs in numerous deep learning tasks, proving the added value of 3D spatial ...information in feature representation. However, the difficulty in collecting more training samples to converge, more computational resources and longer execution time make this approach less applied. Also, applying transfer learning on 3D CNN is challenging due to a lack of publicly available pre-trained 3D models. To tackle these issues, we proposed a novel 2D strategical representation of volumetric data, namely 2.75D. In this work, the spatial information of 3D images is captured in a single 2D view by a spiral-spinning technique. As a result, 2D CNN networks can also be used to learn volumetric information. Besides, we can fully leverage pre-trained 2D CNNs for downstream vision problems. We also explore a multi-view 2.75D strategy, 2.75D 3 channels (2.75D × 3), to boost the advantage of 2.75D. We evaluated the proposed methods on three public datasets with different modalities or organs (Lung CT, Breast MRI, and Prostate MRI), against their 2D, 2.5D, and 3D counterparts in classification tasks. Results show that the proposed methods significantly outperform other counterparts when all methods were trained from scratch on the lung dataset. Such performance gain is more pronounced with transfer learning or in the case of limited training data. Our methods also achieved comparable performance on other datasets. In addition, our methods achieved a substantial reduction in time consumption of training and inference compared with the 2.5D or 3D method.
•We propose a 2.75D strategy, which uses the spiral scanning technique to extract efficient 2D representations of a 3D volume.•We evaluate the proposed methods on three public datasets with different modalities and different organs and demonstrate its remarkable performance in comparison to 2D, 2.5D, and 3D approaches.•We explore the capability and advantage of 2.75D using transfer learning.•We systematically investigate the effect of data size on training yield from different approaches.
In the course of examining the regolith samples delivered to the Earth by the
Luna 16
,
Luna 20
, and
Luna 24
Soviet automatic stations, it was found by means of transmission and scanning electron ...microscopy that the lunar glasses are in general characterized by micro-heterogeneity exhibited both in their composition and in the structure. Moreover, the condensate glass film on the surface of metallic iron grains plays an isolating and protective role preventing oxidation, including under long-term storage under the Earth’s atmosphere.
Purpose
Multiview two‐dimensional (2D) convolutional neural networks (CNNs) and three‐dimensional (3D) CNNs have been successfully used for analyzing volumetric data in many state‐of‐the‐art medical ...imaging applications. We propose an alternative modular framework that analyzes volumetric data with an approach that is analogous to radiologists’ interpretation, and apply the framework to reduce false positives that are generated in computer‐aided detection (CADe) systems for pulmonary nodules in thoracic computed tomography (CT) scans.
Methods
In our approach, a deep network consisting of 2D CNNs first processes slices individually. The features extracted in this stage are then passed to a recurrent neural network (RNN), thereby modeling consecutive slices as a sequence of temporal data and capturing the contextual information across all three dimensions in the volume of interest. Outputs of the RNN layer are weighed before the final fully connected layer, enabling the network to scale the importance of different slices within a volume of interest in an end‐to‐end training framework.
Results
We validated the proposed architecture on the false positive reduction track of the lung nodule analysis (LUNA) challenge for pulmonary nodule detection in chest CT scans, and obtained competitive results compared to 3D CNNs. Our results show that the proposed approach can encode the 3D information in volumetric data effectively by achieving a sensitivity >0.8 with just 1/8 false positives per scan.
Conclusions
Our experimental results demonstrate the effectiveness of temporal analysis of volumetric images for the application of false positive reduction in chest CT scans and show that state‐of‐the‐art 2D architectures from the literature can be directly applied to analyzing volumetric medical data. As newer and better 2D architectures are being developed at a much faster rate compared to 3D architectures, our approach makes it easy to obtain state‐of‐the‐art performance on volumetric data using new 2D architectures.
"This book begins where the reach of archaeology and history ends," writes Charles Hudson. Grounded in careful research, his extraordinary work imaginatively brings to life the sixteenth-century ...world of the Coosa, a native people whose territory stretched across the Southeast, encompassing much of present-day Tennessee, Georgia, and Alabama.Cast as a series of conversations between Domingo de la Anunciacion, a real-life Spanish priest who traveled to the Coosa chiefdom around 1559, and the Raven, a fictional tribal elder,Conversations with the High Priest of Coosaattempts to reconstruct the worldview of the Indians of the late prehistoric Southeast. Mediating the exchange between the two men is Teresa, a character modeled on a Coosa woman captured some twenty years earlier by the Hernando de Soto expedition and taken to Mexico, where she learned Spanish and became a Christian convert.Through story and legend, the Raven teaches Anunciacion about the rituals, traditions, and culture of the Coosa. He tells of how the Coosa world came to be and recounts tales of the birds and animals--real and mythical--that share that world. From these engaging conversations emerges a fascinating glimpse inside the Coosa belief system and an enhanced understanding of the native people who inhabited the ancient South.
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