Episodes Of Expansion Research Articles

The XMM-Newton and NuSTAR view of IRASF11119+3257

Context. IRASF11119+3257 is an ultra-luminous infrared galaxy with a post-merger morphology, hosting a type-1 quasar at z = 0.189. It shows a prominent ultra-fast outflow (UFO) absorption feature (vout ∼ 0.25c) in its 2013 Suzaku spectrum. This is the first system in which the energy released by the UFO was compared to that of the known galaxy-scale molecular outflow to investigate the mechanism driving active galactic nuclei (AGN) feedback. Aims. In 2021, we obtained the first XMM-Newton long look of the target, coordinated with a simultaneous NuSTAR observation, with the goal of constraining the broad band continuum and the nuclear wind physical properties and energetics with an unprecedented accuracy. Methods. The new high-quality data allowed us to clearly detect at a confidence level P > 99.8% multiple absorption features associated with the known UFO at the 9.1 and 11.0 keV rest frames. Furthermore, an emission plus absorption feature at 1.1 − 1.3 keV reveals the presence of a blueshifted P-Cygni profile in the soft band. Results. We associate the two hard band features with blends of FeXXV and FeXXVI Heα-Lyα and Heβ-Lyβ line pairs and infer a large column (NH ∼ 1024 cm−2) of highly ionized (log ξ ∼ 5) gas outflowing at vout = 0.27 ± 0.01c. The 1.3 keV absorption line can be associated with a blend of Fe and Ne transitions, produced by a lower column (NH ∼ 3 × 1021 cm−2) and ionization (log ξ ∼ 2.6) gas component outflowing at the same speed. Using a radiative-transfer disk wind model to fit the highly ionized UFO, we derive a mass outflow rate comparable with the mass accretion rate and the Eddington limit (Ṁout = 4.25−0.73+1.11 M⊙/yr, ∼1.6 Ṁacc and ∼1.0 ṀEdd), and kinetic energy (Ėkin = 1.21−0.20+0.32 Lbol and ∼0.7LEdd) and momentum flux (Ṗout = 6.37−1.09+1.67 Lbol/c) among the highest reported in the literature. We measured an extremely low high-energy cutoff (Ecut ∼ 25 − 30 keV). This and several other cases in the literature suggest that a steep X-ray continuum may be related to the formation of powerful winds. We also analyzed the ionized [OIII] component of the large-scale outflow through optical spectroscopy and derived a large outflow velocity (vout ∼ 3000 km/s) and energetics comparable with the large-scale molecular outflows. Finally, we observe a trend of decreasing outflow velocity from forbidden optical emission lines of decreasing ionization levels, interpreted as the outflow decelerating at large distances from the ionizing source. Conclusions. The lack of a significant momentum boost between the nuclear UFO and the different phases of the large-scale outflow, observed in IRASF11119 and in a growing number of similar sources, can be explained by (i) a momentum-driven expansion, (ii) an inefficient coupling of the UFO with the host interstellar medium, or (iii) by repeated energy-driven expansion episodes with a low duty cycle, that average out on long timescales to produce the observed large-scale outflow.

Aging trajectories of memory CD8 + T cells differ by their antigen specificity.

Memory T cells are a highly dynamic and heterogeneous population that is maintained by cytokine-driven homeostatic proliferation interspersed with episodes of antigen-mediated expansion and contraction which affect their functional state and their durability. This heterogeneity complicates studies on the impact of aging on global human memory cells, specifically, it is unclear how aging drives memory T cell dysfunction. Here, we used chronic infection with Epstein-Barr virus (EBV) to assess the influence of age on memory states at the level of antigen-specific CD8 + T cells. We find that in young adults (<40 years), EBV-specific CD8 + T cells assume preferred differentiation states depending on their peptide specificity. By age >65-years, different T cell specificities had undergone largely distinct aging trajectories, which had in common a loss in adaptive and a gain in innate immunity signatures. No evidence was seen for cellular senescence or exhaustion. While naïve/stem-like EBV-specific T cells disappeared with age, T cell diversity of EBV-specific memory cells did not change or even increased. In summary, by controlling for antigen specificity we uncover age-associated shifts in gene expression and TCR diversity that have implications for optimizing vaccination strategies and adoptive T cell therapy.

Interplay Between Fluid Intrusion and Aseismic Stress Perturbations in the Onset of Earthquake Swarms Following the 2020 Alex Extreme Rainstorm

AbstractThe 2020 Alex storm in southern France led to localized extreme rainfall exceeding 600 mm in less than 24 hr. In the 100 days following the storm, a series of small earthquakes swarm occurred beneath the Tinée valley, a region characterized by a low background deformation. To gain insight into the mechanisms controlling swarm evolution, we used an enhanced seismic catalog to detect 188 events. These events exhibited magnitudes comprised between −1.03 and 2.01, and 78 of them were relocated using relative locations at an average depth of 3–4 km. Additionally, we estimated the directions and velocities of seismicity migration. Our analyses reveal multiple episodes of hypocenter expansion and migration within a fluid‐saturated fault system. Observations provide evidence of a bi‐directional seismicity migration marked by dual velocities within a swarm. The northward seismicity migration aligns with velocities indicative of aseismic slip (∼130 m/hr), while the southward migration corresponds to velocities associated with fluid pressure diffusion (∼5 m/hr). This migration pattern underscores the interplay of multiple physical mechanisms in both triggering and driving earthquakes. A stress‐driven model based on rate‐and‐state friction successfully explains the overall evolution of observed seismicity, whereas a fluid‐driven model fails to reproduce the data. Our observations and models suggest that fluid pressure changes resulting from intense rainfall caused aseismic slip in the shallow portion of the crust. We hypothesize that aseismic deformation serves as the driving force for the earthquake swarms, coupled with the invasion of pressurized fluid due to diffusing rainfall.

Alaska, Hawaii, and the Congressional Politics of Statehood, 1947–1959

Although seldom the subject of systematic analysis, congressional deliberations about granting statehood to Alaska and Hawaii constituted one of the definitive legislative disputes of the immediate post–World War II era, engaging partisan and ideological cleavages, the divisive racial/sectional politics of the time, the “Red Scare,” economic interests, and institutional differences between the House and Senate. Although by the mid-1940s strong support for statehood existed among the public and within most of the advocacy community, admission did not occur until the waning days of the Eisenhower administration, nearly 15 years later. This article clarifies the factors associated with the impasse, including changes that occurred over the 1940s and 1950s, continuities with earlier episodes of national expansion, and the implications for current discussions about statehood for the District of Columbia and Puerto Rico.

Morphometric analysis within populations of Hylomyscus walterverheyeni (Rodentia: Muridae) confirms complex relationships between small rodent populations of West Central African forests

Our recent morphometric study on the strictly forest-dwelling small rodent (Praomys misonnei) in West Central Africa revealed complex relationships between populations. The present study tests this hypothesis on another species of forest rodent (Hylomyscus walterverheyeni), and more precisely compares specimens from Kessala (Gabon) with specimens from southern Cameroon. Sixty-eight specimens were used for the morphometric analyses, and four standard external characters were measured: head + body length, tail length, hindfoot length, and ear length. Highly significant morphometric differences were observed between the H. walterverheyeni populations at the local and regional scales. A principal component analysis showed that the Gabonese H. walterverheyeni populations were morphometrically closer to one another than to the Cameroonian ones. Moreover, the body size of the Gabonese H. walterverheyeni populations was smaller than that of the Cameroonian populations. Overall, H. walterverheyeni is characterized by a local morphometric structure pattern similar to that of P. misonnei. These new results further support the scenario of complex relationships between the forest populations of West Central African rodents. This suggests the existence of persistent local biogeographical barriers despite several forest expansion episodes in the upper Pleistocene, as documented by the landscape history of West Central Africa.

On the State, Potentials, and Current Tensions of the Social Sciences in Latin America

This essay introduces a special collection on the state, potential, and tensions of the social sciences in Latin America. It briefly reflects on the historic role that these disciplines have exerted in society, policy, and culture, their troubled trajectory –– which included episodes of rapid expansion and significant retreatment (if not ostracism) ––, and their current situation in terms of institutional development and research agendas. It also elaborates on how Latin American social scientists have dealt with the difficulties (but also potentials) of studying social structures from a peripheral global region and how they have dealt with the classic tension between involvement and detachment. Against this backdrop, this special collection includes a series of papers exploring how certain topics of especial importance in Latin America –– i.e. development and world economy; state capacity, public administration, and political legitimacy; and violence, conflict, and social cohesion –– have been studied. It also features a group of papers examining some of the main recent institutional and intellectual trends within local social sciences: academic professionalization vis-a-vis activism, the expansion of teaching in the under and graduate levels and its effects on disciplinary borders, the “parochialism” (vs. cosmopolitanism) in publishing and research topics, as well as the potentials and risks of the adoption of open science as recently encouraged by UNESCO. While it would be pointless to attempt to provide a detailed portray of a much-diversified reality, the variety of topics addressed by the papers, as much as the different approaches guiding each contribution ––which range from detached descriptions to normative policy-oriented (and well-informed) essays, from “distant reading” based on bigdata to rich sociohistorical reconstruction––, try to convey some of Latin American social sciences’ vitality and diverse interests.

East Antarctic Ice Sheet variability during the middle Miocene Climate Transition captured in drill cores from the Friis Hills, Transantarctic Mountains

This study describes 16 well-dated, terrestrial glacial sedimentary cycles deposited during astronomically paced climate cycles from the termination of the Miocene Climatic Optimum (MCO) through the middle Miocene Climate Transition (MMCT) (15.1−13.8 Ma) in the Friis Hills, Transantarctic Mountains, Antarctica. Three locations were continuously cored (79% recovery) to a maximum depth of 50.48 m through a succession of interbedded till sheets and fossil-bearing, fluvio-lacustrine sediments. A composite chronostratigraphic framework is presented for the cores based on the previous mapping, a seismic refraction survey that defines basin geometry, and a new, integrated age model based on paleomagnetic stratigraphy that is constrained by radioisotopic 40Ar/39Ar numeric ages on two newly identified silicic tephra. The paleoecologic and sedimentologic characteristics of organic-rich lithologies are relatively consistent up-section, which implies that successively younger interglacial deposits during the MMCT represented broadly similar environmental and climatic conditions. During these interglacials, the Friis Hills hinterland was likely ice-free. Major disconformities in the section suggest a transition to colder climates, and after ca. 14.6 Ma, thicker, more extensive and erosive ice cover occurred across the Friis Hills during glacial episodes. Diamictites in the upper three cycles suggest that climate cooled and became drier after ca. 14.2 Ma. However, cyclical retreat of the ice and a return to warm climate conditions during interglacials continued through ca. 13.9 Ma. These direct records reflect a highly variable East Antarctic Ice Sheet margin but show that the ice margin became progressively more extensive during successive glacial intervals, which is consistent with a cooling trend toward more glacial values in the far-field benthic foraminifera δ18O proxy ice volume and temperature record. Age constraints show that glacial-interglacial variability at the terrestrial margin of the East Antarctic Ice Sheet was primarily paced by astronomical precession (∼23 k.y.) through the onset of the MMCT (15−14.7 Ma). Precession-driven cycles are modulated by short-period (∼100 k.y.) eccentricity cycles. Intervals of maximum eccentricity (high seasonality) coincide with sedimentary cycles comprising thin diamictites and relatively thick interglacial sandstone and mudstone units. Intervals of minimum eccentricity (low seasonality) coincide with sedimentary cycles comprising thick diamictites and relatively thin interglacial sedimentary deposits. Major disconformities in the Friis Hills succession that span more than ∼100 k.y. reflect episodes of expansion of erosive ice across, and well beyond, the Transantarctic Mountains and coincide with nodes in eccentricity (∼400 k.y.). These relationships suggest that during relatively warm intervals in the middle Miocene, the East Antarctic Ice Sheet expanded and contracted over 100 k.y. cycles, while its margins continued to fluctuate at higher (∼23 k.y.) frequency. After 14.5 Ma, obliquity is the dominant frequency in δ18O records, marking a period during which large regions of the Antarctic Ice Sheet grounded in marine environments.

Strontium isotope and element constraints on the paleoenvironment of the latest Ediacaran in the Sichuan Basin, southeastern Tibetan Plateau

The Ediacaran–Cambrian period witnessed episodic extinctions, oxygenation of seawaters, Cambrian explosions, and tectonic events. However, compared with the various high-resolution geochemical records of the early–middle Ediacaran and Cambrian, the available geochemical record of the latest Ediacaran (551–542 Ma) is scarce (especially the strontium isotope and elements), which leads to the ambiguous interpretation of the paleoenvironment of the latest Ediacaran. Therefore, we conducted measurements of strontium isotopes and elemental content of a continuous series of carbonate samples from the Dengying Formation of Well PT1, located in the Sichuan Basin, southeastern Tibetan Plateau, in order to constrain the paleoenvironment of the latest Ediacaran. Strict sample screening was used to ensure that the isotopes and elements were not affected by diagenesis. Our analyses show that the environment and geochemical records of the seawater were controlled by tectonic activities, especially the Gondwana assembly. The global strontium isotope correlation indicates that the Sichuan Basin was a restricted basin (high 87Sr/86Sr values, ∼0.7090), which can be attributed to the existence of a submarine high. Under the background of oxic environment, there were two episodes of anoxic expansion. During the initial stage, the stable terrigenous detrital input and oxic environment provided the prerequisite for the emergence of aerobic organisms in the restricted platform. Then, the decreasing sea level and intense tectonic activities improved the terrigenous detrital input with higher 87Sr/86Sr values (∼0.7095), which stimulated the emergence of aerobic organisms, further resulting in the first episode of anoxic environment. Lastly, a global transgressive resulted in a high sea level, and thus, the Sichuan Basin changed to an open platform. The exchange with extensive oceans led to the increased paleoproductivity, which consumed oxygen and nutrients, further resulting in the second episode of anoxic environment. Thus, the restriction degree, eustatic variations, and the terrigenous detrital input affected the biological evolution and redox conditions.

Biomarkers and PAH chemostratigraphy in the study of the Frasnian anoxic event in the Pimenteiras Formation outcrop of the Parnaíba Basin, Brazil

The Late Devonian is characterized by episodes of sea-level rise and expansion of dysoxic to anoxic paleoenvironments, resulting in a global abundance of organic-rich sedimentary rocks. These changes have been well documented in biostratigraphic studies of Euroamerica basins. However, the relationship between sea-level rise and marine anoxia in Western Gondwana sedimentary rocks is not completely understood. Here, biomarker and PAH diagnostic ratios were applied to investigate changing depositional paleoenvironment and organic matter inputs of the Pimenteiras Formation along the western edge of the Parnaíba Basin. First, 24 shale samples collected from 16 regionally distributed outcrops were analysed, revealing variability in depositional paleoenvironment conditions. Secondly, for detailed study a 15-m thick outcrop was chosen, from which 11 shale samples were collected. These samples were submitted to chemostratigraphic and palynostratigraphic analyses and their records were highlighted. Two sample groups were identified, one sample group containing mixed organic matter, predominantly terrigenous and with fresh-brackish water organisms, deposited under dysoxic conditions. The other sample group comprised mixed organic matter containing a high contribution of marine organisms, preserved under anoxic conditions. Results indicated a marine flooding surface in the Pimenteiras Formation Outcrop 1, associated with a Devonian transgressive event related to sea-level rise and probably to global anoxic conditions during the Frasnian in the Parnaíba Basin. In addition, it was possible to correlate the abundance of miospores Verrucosisporites genus with high Retene/Chrysene values, suggesting that these miospores can be associated with a biological precursor of retene.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Biogeographic history and environmental niche evolution in the palearctic genus Helianthemum (Cistaceae)

The biogeographic history and the degree of environmental niche conservatism provide essential clues to decipher the underlying macroevolutionary processes of species diversification and to understand contemporary patterns of biodiversity. The genus Helianthemum constitutes an excellent case study to investigate the impact of the geo-climatic changes and the environmental niche shifts on the origins of plant species diversity in the Mediterranean hotspot. It is a palearctic species-rich lineage with c. 140 species and subspecies mostly belonging to three distinct evolutionary radiations, almost confined to the Mediterranean region and occurring across varied environmental conditions. In this work, we studied the ample and rapid diversification of the genus Helianthemum across its whole distribution range by performing phylogenetic reconstructions of ancestral ranges and environmental niche evolution. We observed a striking synchrony of biogeographic movements with niche shifts between the three major clades of the genus Helianthemum, likely related to the geo-climatic events occurred in the Mediterranean Basin since the Upper Miocene. In particular, Late Miocene and Early Pliocene were dominated by episodes of range expansions, the Late Pliocene by range contraction and vicariance events, and Pleistocene by most intense environmental niche shifts and in-situ diversification. Our study also provides evidence for four main environmental niches in Helianthemum (i.e., Mediterranean, subdesert, humid-montane and subtropical-insular) and a tendency toward environmental niche conservatism within different subclades, with few niche shifts mostly occurring from Mediterranean ancestors. The relative longer time spent in Mediterranean areas by the ancestors of Helianthemum suggests that the larger species diversity observed in the Mediterranean (i.e. Northern Africa and Southern Europe) may have been generated by a time-for-speciation effect reinforced by environmental niche conservatism. Overall, our work highlights the role of the Mediterranean Basin as a ‘cradle of diversity’ and an ‘evolutionary hub’, facilitating the environmental transitions and determining the building up of a global plant biodiversity hotspot.

Paleoenvironmental reconstruction of the headwaters of the preto river, Minas Gerais state, Brazil, through siliceous bioindicators

The Preto River, located in the municipality of São Gonçalo do Rio Preto (Minas Gerais, Brazil), is one of the few perennial watercourses in the semi-arid region of northeastern Minas Gerais and is essential for the socio-environmental dynamics of the region. Its headwaters are located in the Southern Espinhaço Mountain Range, which is characterized by predominantly quartzite lithologies that form a relief with dissected altimetric variations interspersed with planation surfaces, where the climate is high-altitude tropical. The soils are poorly developed and small fragments of forest, together with phytophysiognomies of the Cerrado Biome such as wet grasslands (Campo limpo úmido), colonize the peatland ecosystems. The aim of this study is to contribute to the paleoenvironmental reconstruction of the headwaters of the River Preto, using sliliceous bioindicators associated with other indicators (multi-proxy analysis). It was possible to infer that there was no change in phytophysiognomies from around 23,330 cal years BP to the present. However, there were 4 periods with oscillations between a cooler, drier environment in the Late Pleistocene, which gradually became warmer and more humid in the Late Holocene. Period 1 (Late Pleistocene) corresponds to the interval from before 23,300 to 13,500 cal years BP, in which the low tree density index (D/P) indicates vegetation similar to the current. Period 2 (end of the Late Pleistocene) corresponds to the period between 13,500 and 11,700 cal years BP. The increase in the D/P index indicates a small expansion of tree vegetation, albeit with the continued predominance of open vegetation. The appearance of Arecaceae characteristic phytoliths, associated with the drop in the climate index (Ic%), indicates an increase in temperature in relation to the previous phase. Period 3 (Pleistocene to Holocene transition) corresponds to the period from 11,700 to 10,000 cal years BP. It is a little colder and drier than the previous period, as observed from the increase in the climate index (Ic%). This period includes the Younger Dryas event, which was colder and drier than currently and had a global influence. Period 4 (Holocene) corresponds to the last 10,000 cal years BP. During this period there was no change in vegetation cover, the D/P and Pa/P indexes remain low, and there is a tendency towards a gradual increase in temperature. The use of siliceous bioindicators associated with other proxies and the regional and global events that occurred during the Quaternary in the analyzed sediments enabled the observation that, at least in the last 23,300 cal years BP, there have been no changes in the local vegetation cover. However, there were small expansion episodes or decreases in the density of tree and Arecaceae cover, as well as a tendency towards increased temperature and humidity in the Upper Holocene. The results proved to be useful for paleoenvironmental research and highlighted how peatland ecosystems are fundamental for understanding the evolution of the landscape and for reconstructing the environmental history of the Cerrado biome.

Resolution and the detection of cultural dispersals: development and application of spatiotemporal methods in Lowland South America

Inferring episodes of expansion, admixture, diffusion, and/or migration in prehistory is undergoing a resurgence in macro-scale archaeological interpretation. In parallel to this renewed popularity, access to computational tools among archaeologists has seen the use of aggregated radiocarbon datasets for the study of dispersals also increasing. This paper advocates for developing reflexive practice in the application of radiocarbon dates to prehistoric dispersals, by reflecting on the qualities of the underlying data, particularly chronometric uncertainty, and framing dispersals explicitly in terms of hypothesis testing. This paper draws on cultural expansions within South America and employs two emblematic examples, the Arauquinoid and Tupiguarani traditions, to develop an analytical solution that not only incorporates chronometric uncertainty in bivariate regression but, importantly, tests whether the datasets provide statistically significant evidence for a dispersal process. The analysis, which the paper provides the means to replicate, identifies fundamental issues with resolution and data quality that impede identification of pre-Columbian cultural dispersals through simple spatial gradients of radiocarbon data. The results suggest that reflexivity must be fed back into theoretical frameworks of prehistoric mobility for the study of dispersals, in turn informing the construction of more critical statistical null models, and alternative models of cultural expansion should be formally considered alongside demographic models.

Fiscal versus Monetary Policy in the 1960s

Abstract. In this lecture, Milton Friedman reviews the role of fiscal and monetary policies on the course of the U.S. business cycle, during several episodes from 1961 to 1969. He relates these developments to shifts in contemporary popular and scientific opinion about the determinants of the business cycle. In each episode of expansion or contraction, he shows that monetary policy – in the sense of changes in the rate of growth of the quantity of money – was at least as important as fiscal policy in determining the pace of economic activity and the rate of inflation, and always dominated when these policies were moving in opposite directions. During the lecture, Friedman makes several digressions to explain the variability of the lag in effect of monetary policy, the reason why interest rates are a poor guide to the stance of monetary policy, and why the downward-sloping liquidity preference function is a poor model that fails to comport with the real world. He also explains why tax increases are not necessarily contractionary, and why tax decreases are not necessarily expansionary. Keywords. Quantity theory, Monetary policy. JEL. E50, E53, E63.

Experimentally Induced Volumetric Re‐equilibration of Plagioclase‐Hosted Melt Inclusions

AbstractThe application of melt inclusions (MI) to infer magmatic processes assumes the MI have remained as constant mass, constant volume systems since the time of trapping. Understanding the effects of both compositional and volumetric re‐equilibration is key for the interpretation of MI data. Although the re‐equilibration behavior MI in quartz and olivine has been studied in some detail, the process is less understood for other MI host phases such as plagioclase, a common phase in igneous rocks. A MI can re‐equilibrate when it experiences pressure and temperature (PT) conditions that differ from formation PT conditions. During laboratory heating, irreversible MI expansion may occur. As a result, the internal pressure within the MI decreases, resulting in chemical and structural changes to the MI and host. We present results of heating experiments on plagioclase‐hosted MI designed to induce volumetric re‐equilibration. The experiments consisted of incrementally heating the MI to temperatures above the homogenization temperatures. At ∼40°C above, the temperature at which the daughter minerals melted, irreversible volume expansion lowered the pressure in the MI, and led to exsolution of CO2 into vapor bubbles. With each additional few degrees of heating, additional episodes of CO2 exsolution, bubble nucleation and expansion of the vapor bubbles occurred. Re‐equilibration of MI in plagioclase occurred through a combination of ductile and brittle deformation of the host surrounding the MI, whereas previous studies have shown that MI in olivine re‐equilibrate dominantly through ductile deformation associated with movement along dislocations. This behavior is consistent with the differing rheological properties of these phases.

Phylogeny and biogeography of some Cretaceous spatangoid echinoids with special emphasis on taxa from the Western Interior Seaway

AbstractMembers of the echinoid order Spatangoida, a highly diverse and abundant marine invertebrate clade, were important denizens of the Cretaceous Western Interior Seaway (WIS), an epicontinental seaway that divided North America in two during an interval of greenhouse conditions between roughly 100 and 65 million years ago. A phylogenetic analysis of spatangoids was conducted using a character matrix of 32 characters from 21 species. Species that occur in the WIS were considered comprehensively, and species from other regions such as South America, Europe, and North Africa were also incorporated into the analysis. Phylogenetic patterns retrieved are largely congruent with preexisting family-level classifications; however, species within several genera, especiallyHemiasterandHeteraster, need to be reassigned so that classification better reflects phylogeny. The generaWashitasterandHeterasterare closely related, as areMecaster,Palhemiaster, andProraster;Pliotoxaster,Macraster, andHemiaster; andMicrasterandDiplodetus. Biogeographic patterns were also considered using the phylogeny, and several episodes of vicariance and range expansion were identified. These were possibly related to some of the various major episodes of sea-level rise and fall during the Cretaceous. In particular, Valangian–mid-Aptian regressions may have caused vicariance withinHeterasterandWashitasterwhile other early spatangoid vicariance may be related to regressions during the late Aptian–early Cenomanian. Further, vicariance caused by regressions during the mid-Cenomanian–Maastrichtian may have driven diversification withinMicrasterandDiplodetus. Last, transgressions during the late Aptian–early Cenomanian seem to have spurred prominent range expansions inMecasterandHemiaster.

The SARS-CoV-2 Pandemic in Latin America: the Need for Multidisciplinary Approaches.

Purpose of ReviewAcute respiratory infections of viral etiology (ARIVE) constitute one of the most frequent infectious processes among humans. They cause significant morbidity and mortality every year in all age groups and regions of the world. Their etiology is diverse, and seasonal viruses began their journey, at some point, with an episode of expansion before their annual circulation as seasonal agents. The coronavirus disease 2019 (COVID-19) pandemic is a challenge for Latin America. Understanding dynamics is essential for decision making, to reduce the health, economic, and social impacts of the pandemic.Recent FindingsCurrently, governments in Latin America have taken measures to mitigate the spread of COVID-19 primarily based on World Health Organization recommendations. However, the potential impact of the virus in Latin America is still unknown. Given the urgency, governments need more accurate estimates of what could happen in Latin America in order to make informed decisions, At the September 20, 2020, cumulative cases 2295 of COVID-19 per 1 million population has been registered in Latin America and the Caribbean. Brazil, Peru, and Chile are the most countries affected by this pandemic, registering a total of cumulative cases per million inhabitants of 21,148, 22,941, and 23,262 respectively. Peru has shown the highest death numbers with 949 per million inhabitants.SummaryThe Latin American health authorities should make the most beneficial decisions based in scientific facts for the health and life of citizens, both understood in the broadest and most inclusive sense.Once the epidemic is over, Latin America should begin a profound health reform, at a single and universal health system, integrated and coordinated, where the leading role of the Ministry of Health is resumed, to have a national network of modern, integrated, and excellent quality laboratories for the benefit of the entire society.

High-quality chromosome-level genomes of two tilapia species reveal their evolution of repeat sequences and sex chromosomes.

Tilapias are one of the most farmed fishes that are coined as "aquatic chicken" by the food industry. Nile tilapia and blue tilapia exhibit very recent transition of sex chromosome systems since their divergence approximately five million years ago, making them a great model for elucidating the molecular and evolutionary mechanisms of sex chromosome turnovers. Studies of their sex-determining pathways are also critical for developing genetic sex control in aquaculture. We report here the newly produced genomes of Nile tilapia and blue tilapia that integrate long-read sequencing and chromatin conformation data. The two nearly complete genomes have anchored over 97% of the sequences into linkage groups (LGs), and assembled majorities of complex repetitive regions including telomeres, centromeres and rDNA clusters. In particular, we inferred two episodes of repeat expansion at LG3 respectively in the ancestor of cichlids and that of tilapias. The consequential large heterochromatic region concentrated at one end of LG3 comprises tandem arrays of mRNA and small RNA genes, among which we have identified a candidate female determining gene Paics in blue tilapia. Paics shows female-specific patterns of single-nucleotide variants, copy numbers and expression patterns in gonads during early gonadogenesis. Our work provides a very important genomic resource for functional studies of cichlids, and suggested that unequal distribution of repeat content that impacts the local recombination rate might make some chromosomes more likely to become sex chromosomes.

The Callander (Auchenlaich) moraine: A new site report for the Western Highland Boundary block of the Quaternary of Scotland Geological Conservation Review (GCR)

The Callander Moraine (also known locally as the Auchenlaich Moraine) is an exceptionally well-preserved glacial landform on the outskirts of the town of Callander, in the council district of Stirling. It is part of an assemblage of neighbouring glacial landforms and sedimentary sequences which include eskers, kame terraces and kettle holes. When viewed both individually and together these features provide evidence for the interpretation of the nature, timing and extent of an ice margin at one of the south-eastern limits of the main icefield that occupied the Western Highlands during the Loch Lomond Readvance (Lowe, 1993), the last episode of glacial expansion to affect Scotland. This site description forms a new inclusion of the site into the Quaternary of Scotland Geological Conservation Review (GCR). The Callander Moraine is a key feature because it one of the best constrained of the ice limits dating to this glacial episode: sedimentary sequences within kettle hole basins closely located on both the up-valley (GCR site at Mollands) and down-valley (GCR site at Tynaspirit) sides of the moraine provide stratigraphic and independent dating evidence for the age of the feature, although recent advances in dating methods should allow significant refinement of the current age estimate. Although much remains to be clarified about the origin and age of the Callander Moraine, this very close association between a terminal moraine of Loch Lomond Readvance age and datable deposits that bracket its age makes it unique in the UK, and a key target for future research. Finally, there is presently an emerging debate over the pattern and timing of disintegration of the Loch Lomond Readvance ice masses, the last to occupy the Highlands of Scotland, an important topic in which the evidence from the nationally important site of the Callander Moraine, together with the assemblage of surrounding glacial landforms and sediments, can continue to play a pivotal role.

Palaeoenvironmental change and glacier fluctuations in the high Tian Shan Mountains during the last millennium based on sediments from Lake Ala Kol, Kyrgyzstan

A suite of limnological proxies measured in clastic sediments of the glacier-fed Lake Ala Kol (NE Kyrgyzstan) document palaeoenvironmental change and glacier fluctuations in the central Tian Shan over the last millennium. Rock magnetic and geochemical data provide supporting evidence for three glacier expansion episodes occurring in 1200–1400 CE, 1500–1850 CE and 1900–1950 CE and glacier retreat periods during 1000–1200 CE and the intervening periods. The maximal glacier extent, as inferred from high κLF, Si/inc + coh, Ca/inc + coh and low ARM30/ARM, is recorded between 1500 and 1850 CE and corresponds to cold and wet conditions during the Little Ice Age in the high central Tian Shan. Periods of glacier waxing and waning recorded at Lake Ala Kol present a close correspondence to ice accumulation rate in the northern Tibetan Plateau, suggesting that precipitation changes are the main driver of glacier fluctuations in central Tian Shan during the last millennium, although temperature may have exerted a more complex influence on centennial timescales.