Isotopic analysis of Fe has proved to be a productive tool for the study of the formation and evolution of planetary bodies. The Fe isotopic studies on the Moon revealed that low-Ti and high-Ti ...basalts are positively correlated with TiO2 contents, indicating the occurrence of Fe isotopic fractionation during lunar magma ocean differentiation (Weyer et al., 2005; Liu et al., 2010; Wang et al., 2015; Sossi and Moynier, 2017). If true, very low-Ti basalts may be more representative of the lunar mantle than high-Ti and low-Ti basalts. Thus, an Fe isotopic study of very low-Ti basalts is required to investigate the Fe isotopic evolution scenario during lunar magma ocean differentiation.
In this study, we measured Fe isotopic ratios of soil samples from the Soviet Luna missions, Luna 16, 20, and 24, using MC-ICP-MS. Bulk soil samples without isolation of components and separated monomineralic grains (olivine, pyroxene, and agglutinate) were dedicated for the Fe isotopic study. Among our samples, Luna 24 soil is recognized as very low-Ti basalt. Evidence of non-mass-dependent Fe isotopic fractionation was not found in bulk soils and separated monomineralic olivine, pyroxene, and agglutinate grains. Lunar regolith samples are weathered by meteorite impacts on the Moon’s surface. A mature regolith sample, L1613, showed clearly distinguished Fe isotopic compositions between the fine-grained fraction (δ57Fe = 0.54 ± 0.06‰) and the coarse-grained fraction (δ57Fe = 0.20 ± 0.06‰). Such Fe isotopic differences among different size fractions were smaller in the submature sample (L2001) and the immature sample (L24130.3). The Fe isotopic ratios of separated grains show that agglutinates have higher δ57Fe values than bulk and monomineralic grains, indicating abundant nanophase Fe in agglutinates and partial evaporation of Fe during its melting.
The δ57Fe value for the coarsest-grained fraction of L24130.3 was found to be 0.08 ± 0.04‰, which is the first Fe isotopic composition reported for lunar samples with very low-Ti mare basalt composition. This value is clearly lower than previously reported δ57Fe values for high-Ti and low-Ti basalts and is nearly identical to those of Mg-suite rocks. This observation is consistent with the Fe isotopic evolution model during lunar magma ocean differentiation (Sossi and Moynier, 2017). Our results related to very low-Ti basalt showed that the bulk silicate Moon has lower Fe isotopic composition than the value estimated from averaged low-Ti or high-Ti basalts.
Given the data known to date, including our results, we conclude that it is most likely that Earth and the Moon have the same Fe isotopic composition. We believe that isotopically heavy Fe of silicate Earth is balanced by isotopically light Fe of Earth’s core, as suggested by Galimov’s (2011) model for the formation of the Earth-Moon system.
Bulk composition data for 24 chemical elements are presented for regolith samples (<1 mm fines) from each of the 62 half‐centimeter dissection intervals along the 31 cm length of the 76001 vertical ...drive tube collected by astronauts at the base of the North Massif at station 6 of the Apollo 17 landing site. The core regolith is nearly uniform in composition with depth although the concentrations of Sc and Sm, for example, decrease from 28.5 μg g−1 Sc and 5.93 μg g−1 Sm at the top 2.5 cm to 26.9 μg g−1 Sc and 5.55 μg g−1 Sm at the bottom 2.5 cm. This change reflects an increase with depth in the relative abundance of Sm‐poor, feldspathic material, from 48.4% at the top to 50.1% at the bottom. On the basis of compositional mass balance, the feldspathic (nonmare) material of the station 6 regolith requires a substantial proportion of an Mg‐rich lithology, ~27% when modeled as troctolite sample 76535. The remaining 73% is nominally Sm‐poor anorthositic norite in composition. No such Mg‐rich component is required to account for the composition of the regolith of the South Massif (stations 2 and 3). The total feldspathic component of the North Massif regolith, normatively an anorthositic troctolite (74 vol% plagioclase, olivine:pyroxene = 55:45, Mg′ = 78%), is very similar to that of the nonmare component of the Luna 20 regolith collected 910 km to the southeast on the Crisium ejecta deposit. We also present new composition data for 21, 25, and 16 small lithic fragments (0.1–3.9 mg each) from the regoliths of the Luna 16, 20, and 24 missions.
This paper investigates the causes and the consequences of the FTX digital currency exchange’s failure in November 2022. Analysing on-chain data, we report that FTX heavily relied on leveraging and ...misusing its native token, FTT, and we show how this behaviour exacerbated the company’s fragile financial situation. To gain further insights into the downfall, we employ state-of-the-art network science instruments to model the evolutionary dependency structures of 199 cryptocurrencies on an hourly basis, and we investigate tick-by-tick public trades at the time of the events. We identify the collapse of the Terra-Luna ecosystem as the pivotal event that triggered a significant decrease in the exchange’s liquidity. Results suggest that the crash was actively accelerated by Binance tweets causing a systemic reaction in the cryptocurrency market. Finally, identifying the actors who mostly benefited from the FTX’s collapse and highlighting a generalised trend toward centralisation in the crypto space, we emphasise the importance of genuinely decentralised finance for a transparent, future digital economy.
•We investigate the causes and the consequences of the FTX exchange’s failure.•We use hourly closing price, on-chain data and public transaction data.•We use state-of-the-art instruments from network science (i.e., TMFG).•We identify the collapse of the Terra-Luna as the trigger for the FTX’s crash.•We highlight a generalised trend toward centralisation in the crypto space.
We quantitatively describe the main events that led to the Terra project’s failure in May 2022. We first review, in a systematic way, news from heterogeneous social media sources; we discuss the ...fragility of the Terra project and its vicious dependence on the Anchor protocol. We hence identify the crash’s trigger events, analysing hourly and transaction data for Bitcoin, Luna, and TerraUSD. Finally, using state-of-the-art techniques from network science, we study the evolution of dependency structures for 61 highly capitalised cryptocurrencies during the down-market and we also highlight the absence of herding behaviour analysing cross-sectional absolute deviation of returns.
•We describe the Terra project’s features and the mechanisms that led to its failure.•We use network science and herding approaches to capture dependency structures.•The vicious dependence of the Terra project on the Anchor protocol is reported.•We uncover BTC’s reference role during the first phase of the collapse.•Herding behaviour is not detected during the down market.
The results of our regional and local studies of the Fecunditatis basin and Mare Fecunditatis, and areas adjacent to the Luna 16 landing site suggest the following. If the Fecunditatis basin is an ...impact structure, which is consistent with the crustal thickness models and gravity data, it predates the Nectaris basins (∼4.17 Ga). The unusually flat topographic profile of the Fecunditatis basin can be explained by viscous relaxation of the original topography of the basin and the subsequent filling of the basin by ejecta from the Nectaris and Crisium basins. The results of our crater size-frequency measurements within the mare domain of the Fecunditatis basin yield an absolute model age (AMA) of ∼3.81 Ga. Thus, the population of all recognizable craters within Mare Fecunditatis denotes the existence of an extensive episode/episodes of resurfacing that has erased the ancient crater population accumulated after the Fecunditatis impact event but before the mare emplacement. Our determinations of AMAs of the surface of Mare Fecunditatis (∼3.45 Ga) are consistent with most radiometric age determinations from the Luna 16 samples that are clustered at ages of ∼3.5–3.4 Ga. The current Mare Fecunditatis surface is likely to represent the latter episodes of volcanism, the main phase of which was active during this time interval. Although older radiometric ages have not yet been reported, the presence of older basalts in the Luna 16 sample should not be ruled out, taking into account the likely multiple sources of its materials and the complex nature of the emplacement of lavas in Mare Fecunditatis. The thickness of mare basalts in Mare Fecunditatis are highly variable. At the regional scale, thicknesses are most likely at least ∼1.5 km, in order to be able to hide a significant number of ancient larger craters. In the areas of partly or completely flooded craters, the mare thickness increases up to ∼2–2.7 km. In the vicinity of the Luna 16 landing site, however, the thickness of the most than a few hundred meters.
•The unusual topographic profile of the Fecunditatis basin can be explained by viscous relaxation of the original topography.•Recognizable craters within Mare Fecunditatis suggest the existence of an extensive episode of resurfacing before the mare emplacement.•Our determinations of AMAs of the surface of Mare Fecunditatis (∼3.45 Ga) are consistent with most radiometric age determinations from the Luna 16 samples (∼3.5–3.4 Ga).•Older radiometric age of Mare Fecunditatis materials should not be ruled out.
En la serie de cuadernos del seminario de la Universidad Nacional Autónoma de México, “Modernidad: versiones y dimensiones”, dirigido por Marta Lamas y que ha sido coordinado anteriormente por Raquel ...Serur y por su fundador Bolívar Echeverría, Andrés Luna Jiménez, un joven historiador, ha publicado un libro notable: Figuras de la crítica: la (de)formación del sujeto como problema histórico en Marcuse, Foucault y Butler. El libro contiene virtudes difíciles de alcanzar en la academia actual: muestra una clara voz autoral; un hilo argumental sostenido, profundo y, a la vez, pedagógico; y actualiza con sutileza los debates, los enfrenta y los coloca bajo una perspectiva abierta a la investigación filosófica contemporánea.
Space exploration missions have placed renewed focus on the South Circumpolar Region (SCR) of the Moon due to its unexplored nature by landed missions, potential water resources, proximity to the ...ancient South Pole-Aitken (SPA) basin, and the presence of regions that provide near-permanent solar illumination. Unlike previous surface exploration sites, the SCR lacks extensive mare regions and is most similar to the Apollo 16 and Luna 20 sites, and is dominated by overlapping deposits of impact craters and basins of a wide range of sizes and ages. This renders the geologic history of individual regions difficult to determine, and the provenance of returned samples potentially enigmatic. In order to help alleviate these problems and to provide a consistent geological framework for landing site selection, mission planning and operations, and interpreting sample provenance, we have compiled a new geologic map of the SCR (1:300000 mapping scale; South pole to 70°S) using the most recently acquired orbital data (LRO LROC WAC 100 m/pix resolution image data and LOLA-based 80–20 m/pix resolution DTMs), and portraying geological units, features and structures, stratigraphic sequences, and providing a framework to address many outstanding problems in lunar science. We define and map several major types of units and structures: (1) high-standing massifs of the SPA basin, (2) crater-related units – walls, rims, and ejecta of impact craters and smaller basins, (3) plains units of both impact (impact melt and/or Cayley Formation) and volcanic origins (lava fields and pyroclastic deposits) and (4) landforms related to degradation of crater topography. Absolute Model Ages (AMAs) derived from crater size-frequency distribution (CSFD) measurements for ∼200 of these units/structures, whose relative ages were determined by superposition relations, were used to compile a correlation of map units for the SCR region.
Cáncer y sus mecenas González Maya, Juan Carlos
Hipogrifo (New York, NY),
06/2024, Letnik:
12, Številka:
1
Journal Article
Odprti dostop
The poet Jerónimo de Cáncer y Velasco is known above all as a come-diographer and “entremesista”, genres in which he made his fame, but occasionally, as he tells us, he found it necessary to beg. ...From there arose his poetry of patronage, somewhere between the praise or vituperation of people of the courtly circle of Philip IV, and his self-portrait with burlesque overtones. The results of his reception were unequal and in them one can also glimpse the meanness of the aristocracy. His most direct dealings were with Don Gaspar Alonso Pérez de Guzmán el Bueno, IX Duke of Medina Sidonia, and with his son Gaspar Juan Alonso Pérez de Guzmán el Bueno, XIV Count of Niebla, to whom he asked for help for the publication of his Obras varias (1651). He maintained a cordial and complimentary relationship with them. His second protector was Don Antonio Alfonso Pimentel, IX Count of Luna, the firstborn of the Count-Duke of Benavente, with whom he seems to have been one of the accountants of his house, but with whom he had a more complicated relationship due to the degree of abandonment to which he was subjected. Unfor-tunately, it has not been possible to confirm these data in the consultations with the archives of the Medina Sidonia Foundation and Nobility
El poeta Jerónimo de Cáncer y Velasco es conocido sobre todo como comediógrafo y entremesista, géneros donde labró su fama, pero ocasionalmente, y según él mismo nos cuenta, se vio en la necesidad de pedir. De ahí surge su poesía de mecenazgo, a camino entre el elogio o vituperio de personas del círculo cortesano de Felipe IV, y su autorretrato con tintes burlescos. Los resultados de su acogida fueron desiguales y en ellos se puede vislumbrar también la mezquindad de la aristocracia. Su trato más directo fue con don Gaspar Alonso Pérez de Guzmán el Bueno, IX duque de Medina Sidonia, y con su hijo don Gaspar Juan Alonso Pérez de Guzmán el Bueno, XIV conde de Niebla, a los que pedía ayuda para la publicación de sus Obras varias (1651). Con ellos mantiene un trato cordial y elogioso. Su segundo protector fue don Antonio Alfonso Pimentel, IX conde de Luna, primogénito del conde-duque de Benavente, de quien parece fue uno de los contadores de su casa, pero con quien tuvo una relación más complicada por el grado de abandono al que lo tenía sometido. Lamentablemente, no se han podido confirmar estos datos en las consultas a los archivos de la Fundación Medina Sidonia y de Nobleza
