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1.
Nature ; 568(7750): 55-60, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30890786

RESUMEN

NASA'S Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft recently arrived at the near-Earth asteroid (101955) Bennu, a primitive body that represents the objects that may have brought prebiotic molecules and volatiles such as water to Earth1. Bennu is a low-albedo B-type asteroid2 that has been linked to organic-rich hydrated carbonaceous chondrites3. Such meteorites are altered by ejection from their parent body and contaminated by atmospheric entry and terrestrial microbes. Therefore, the primary mission objective is to return a sample of Bennu to Earth that is pristine-that is, not affected by these processes4. The OSIRIS-REx spacecraft carries a sophisticated suite of instruments to characterize Bennu's global properties, support the selection of a sampling site and document that site at a sub-centimetre scale5-11. Here we consider early OSIRIS-REx observations of Bennu to understand how the asteroid's properties compare to pre-encounter expectations and to assess the prospects for sample return. The bulk composition of Bennu appears to be hydrated and volatile-rich, as expected. However, in contrast to pre-encounter modelling of Bennu's thermal inertia12 and radar polarization ratios13-which indicated a generally smooth surface covered by centimetre-scale particles-resolved imaging reveals an unexpected surficial diversity. The albedo, texture, particle size and roughness are beyond the spacecraft design specifications. On the basis of our pre-encounter knowledge, we developed a sampling strategy to target 50-metre-diameter patches of loose regolith with grain sizes smaller than two centimetres4. We observe only a small number of apparently hazard-free regions, of the order of 5 to 20 metres in extent, the sampling of which poses a substantial challenge to mission success.


Asunto(s)
Medio Ambiente Extraterrestre/química , Planetas Menores , Vuelo Espacial , Exobiología , Origen de la Vida , Vuelo Espacial/instrumentación , Propiedades de Superficie
2.
Public Health ; 194: 19-24, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33845275

RESUMEN

OBJECTIVES: COVID-19 infection has been compared to seasonal influenza as an argument against non-pharmacological population-based infection control measures known as "lockdowns". Our study sought to compare disease severity measures for patients in Ireland hospitalised with COVID-19 against those hospitalised with seasonal influenza. STUDY DESIGN: This is a retrospective population-based cohort study. METHODS: COVID-19 hospital episodes and seasonal influenza hospital episodes were identified using relevant International Classification of Disease (ICD-10) codes from the Irish national hospitalisation dataset. The occurrences of key metrics of disease severity, length of stay, intensive care admission, ventilatory support, haemodialysis and in-hospital mortality were measured and compared between the two groups using odds ratios with 95% confidence intervals (CIs), stratified by age. RESULTS: Hospitalised COVID-19 episodes had a mean length of stay more than twice as long as hospitalised influenza episodes (17.7 days vs 8.3 days). The likelihood of all measures of disease severity was greater in COVID-19 episodes, and the odds of in-hospital mortality were five-fold higher in this group compared with seasonal influenza episodes (OR 5.07, 95% CI 4.29-5.99, P < 0.001). Greater likelihood of increased disease severity was observed for COVID-19 episodes in most age groups. CONCLUSIONS: COVID-19 is a more severe illness than seasonal influenza in hospitalised cohorts. It is imperative that public health professionals ensure that evidence-based advocacy is part of the response to COVID-19 to tackle a dangerous "infodemic" that can undermine public health control measures.


Asunto(s)
COVID-19/terapia , Hospitalización/estadística & datos numéricos , Gripe Humana/terapia , Difusión de la Información , Índice de Severidad de la Enfermedad , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , COVID-19/epidemiología , COVID-19/mortalidad , COVID-19/prevención & control , Niño , Preescolar , Femenino , Mortalidad Hospitalaria/tendencias , Humanos , Lactante , Recién Nacido , Gripe Humana/epidemiología , Gripe Humana/mortalidad , Irlanda/epidemiología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Adulto Joven
3.
Space Sci Rev ; 220(1): 1, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38130909

RESUMEN

The Lucy Thermal Emission Spectrometer (L'TES) will provide remote measurements of the thermophysical properties of the Trojan asteroids studied by the Lucy mission. L'TES is build-to-print hardware copy of the OTES instrument flown on OSIRIS-REx. It is a Fourier Transform spectrometer covering the spectral range 5.71-100 µm (1750-100 cm-1) with spectral sampling intervals of 8.64, 17.3, and 34.6 cm-1 and a 7.3-mrad field of view. The L'TES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly to a single uncooled deuterated l-alanine doped triglycine sulfate (DLATGS) pyroelectric detector. A significant firmware change from OTES is the ability to acquire interferograms of different length and spectral resolution with acquisition times of 0.5, 1, and 2 seconds. A single ∼0.851 µm laser diode is used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target, together with observations of space, provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2 × 10-8 W cm-2 sr-1 /cm-1 between 300 and 1350 cm-1. The absolute temperature error is <2 K for scene temperatures >75 K. The overall L'TES envelope size is 37.6 × 29.0 × 30.4 cm, and the mass is 6.47 kg. The power consumption is 12.6 W average. L'TES was developed by Arizona State University with AZ Space Technologies developing the electronics. L'TES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ. Initial data from space have verified the instrument's radiometric and spatial performance.

4.
J Emerg Med ; 42(3): 353-62, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-20692786

RESUMEN

BACKGROUND: Delivery of critical care within a certain window of opportunity is paramount in many disease states, and providing the right care to these patients at the right time in the Emergency Department (ED) can significantly reduce mortality. However, aggressive treatment of these patients often requires endotracheal intubation and mechanical ventilation either in the pre-hospital or ED phase of care. Care of mechanically ventilated patients in the ED is not trivial or without potential complications, including ventilator-associated pneumonia (VAP). OBJECTIVE/DISCUSSION: This article summarizes the epidemiology, pathophysiology, and specific risk factors associated with VAP and provides evidence-based recommendations for its prevention. We emphasize practices that are particularly important in the early stages of care of intubated, mechanically ventilated patients; thus, they should be instituted in the ED. CONCLUSION: Specifically, we recommend continuous backrest elevation of 30-45°, chlorhexidine application to the oral cavity after intubation and every 12h thereafter, orotracheal intubation with a tube that enables continuous subglottic suctioning, and cuff pressure assessments after intubation and every 4h thereafter to maintain pressure between 20 and 30cm H(2)O.


Asunto(s)
Medicina de Emergencia Basada en la Evidencia , Neumonía Asociada al Ventilador/prevención & control , Humanos , Intubación Intratraqueal/métodos , Neumonía Asociada al Ventilador/etiología , Postura , Factores de Riesgo , Gestión de Riesgos/métodos
5.
Nat Commun ; 13(1): 364, 2022 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-35042881

RESUMEN

The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu's emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.

6.
Science ; 377(6603): 285-291, 2022 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-35857591

RESUMEN

Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu's surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-meter-long elliptical crater. This exposed material is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500 to 700 kilograms per cubic meter, which is about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 grams of material, which will be delivered to Earth in 2023.

7.
Nature ; 436(7050): 504-9, 2005 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-16007077

RESUMEN

Compositional mapping of Mars at the 100-metre scale with the Mars Odyssey Thermal Emission Imaging System (THEMIS) has revealed a wide diversity of igneous materials. Volcanic evolution produced compositions from low-silica basalts to high-silica dacite in the Syrtis Major caldera. The existence of dacite demonstrates that highly evolved lavas have been produced, at least locally, by magma evolution through fractional crystallization. Olivine basalts are observed on crater floors and in layers exposed in canyon walls up to 4.5 km beneath the surface. This vertical distribution suggests that olivine-rich lavas were emplaced at various times throughout the formation of the upper crust, with their growing inventory suggesting that such ultramafic (picritic) basalts may be relatively common. Quartz-bearing granitoid rocks have also been discovered, demonstrating that extreme differentiation has occurred. These observations show that the martian crust, while dominated by basalt, contains a diversity of igneous materials whose range in composition from picritic basalts to granitoids rivals that found on the Earth.

8.
J Geophys Res Planets ; 126(2): e2020JE006624, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33777607

RESUMEN

We describe the capabilities, radiometric stability, and calibration of a custom vacuum environment chamber capable of simulating the near-surface conditions of airless bodies. Here we demonstrate the collection of spectral measurements of a suite of fine particulate asteroid analogs made using the Planetary Analogue Surface Chamber for Asteroid and Lunar Environments (PASCALE) under conditions like those found on Earth and on airless bodies. The sample suite includes anhydrous and hydrated physical mixtures, and chondritic meteorites (CM, CI, CV, CR, and L5) previously characterized under Earth- and asteroid-like conditions. And for the first time, we measure the terrestrial and extra-terrestrial mineral end members used in the olivine- and phyllosilicate-dominated physical mixtures under the same conditions as the mixtures and meteorites allowing us better understand how minerals combine spectrally when mixed intimately. Our measurements highlight the sensitivity of thermal infrared emissivity spectra to small amounts of low albedo materials and the composition of the sample materials. As the albedo of the sample decreases, we observe smaller differences between Earth- and asteroid-like spectra, which results from a reduced thermal gradient in the upper hundreds of microns in the sample. These spectral measurements can be compared to thermal infrared emissivity spectra of asteroid (101955) Bennu's surface in regions where similarly fine particulate materials may be observed to infer surface compositions.

9.
Sci Rep ; 10(1): 19156, 2020 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-33154480

RESUMEN

Non-classical crystallisation (NCC) pathways are widely accepted, however there is conflicting evidence regarding the intermediate stages of crystallisation, how they manifest and further develop into crystals. Evidence from direct observations is especially lacking for small organic molecules, as distinguishing these low-electron dense entities from their similar liquid-phase surroundings presents signal-to-noise ratio and contrast challenges. Here, Liquid Phase Electron Microscopy (LPEM) captures the intermediate pre-crystalline stages of a small organic molecule, flufenamic acid (FFA), a common pharmaceutical. High temporospatial imaging of FFA in its native environment, an organic solvent, suggests that in this system a Pre-Nucleation Cluster (PNC) pathway is followed by features exhibiting two-step nucleation. This work adds to the growing body of evidence that suggests nucleation pathways are likely an amalgamation of multiple existing non-classical theories and highlights the need for the direct evidence presented by in situ techniques such as LPEM.


Asunto(s)
Cristalización , Ácido Flufenámico/química , Microscopía Electrónica/métodos
10.
Ann R Coll Surg Engl ; 102(3): 220-224, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31755733

RESUMEN

INTRODUCTION: Follow-up after hip and knee arthroplasty is advocated to identify asymptomatic loosening and improve patient satisfaction. There are, however, financial and time implications associated with regular clinic appointments. Assessment through virtual means has been suggested as an alternative. MATERIALS AND METHODS: At the West Suffolk Hospital, following arthroplasty surgery of the lower limb, patients are followed-up via a questionnaire at one and five years postoperatively, then subsequently at five-yearly intervals. Patients are recalled based on the outcome of these assessments. Using a locally compiled data base we identified all patients reviewed between 2011 and 2015 using this virtual assessment process and examined their outcomes. RESULTS: During the five years of follow-up, 5,380 patients were eligible for assessment. Compliance varied from 77% follow up for hips and 83% for knees. Ten patients were recalled following total hip replacement, eight for x-ray changes and one for a poor satisfaction score. Five went on to undergo revision surgery. Some 56 recalls to clinic following knee arthroplasty were seen; 42 due to a poor Oxford Knee Score, 6 with associated x-ray abnormalities and 6 isolated abnormal x-rays. Five subsequently underwent revision surgery; 30 (54%) were discharged after initial review and 18 (32%) were referred to different subspecialties.As a result of the virtual review process, 4,219 clinic appointments were avoided, with no documented admissions as a result of a missed complication from virtual review. DISCUSSION: A virtual arthroplasty clinic significantly reduces the number of patients attending regular follow-up clinics, without compromising safe practice.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Artroplastia de Reemplazo de Rodilla , Hospitales de Distrito , Hospitales Generales , Satisfacción del Paciente , Estudios de Seguimiento , Articulación de la Cadera/diagnóstico por imagen , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Reoperación , Encuestas y Cuestionarios , Resultado del Tratamiento , Reino Unido
11.
Nat Astron ; 20202020.
Artículo en Inglés | MEDLINE | ID: mdl-33681472

RESUMEN

Carbonaceous chondrite meteorites record the earliest stages of Solar System geo-logical activities and provide insight into their parent bodies' histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low temperature and pressure aqueous alteration1. Others are dominated by anhydrous minerals and textures that indicate high temperature metamorphism in the absence of aqueous fluids1. Evidence of hydrous metamorphism at intermediate pressures and temperatures in carbonaceous chondrite parent bodies has been virtually absent. Here we show that an ungrouped, aqueously altered carbonaceous chondrite fragment (numbered 202) from the Almahata Sitta (AhS) meteorite contains an assemblage of minerals, including amphibole, that reflect fluid-assisted metamorphism at intermediate temperatures and pressures on the parent asteroid. Amphiboles are rare in carbonaceous chondrites, having only been identified previously as a trace component in Allende (CV3oxA) chondrules2. Formation of these minerals requires prolonged metamorphism in a large (~640-1800 km diameter), unknown asteroid. Because Allende and AhS 202 represent different asteroidal parent bodies, intermediate conditions may have been more widespread in the early Solar System than recognized from known carbonaceous chondrite meteorites, which are likely a biased sampling.

12.
Science ; 370(6517)2020 11 06.
Artículo en Inglés | MEDLINE | ID: mdl-33033155

RESUMEN

The composition of asteroids and their connection to meteorites provide insight into geologic processes that occurred in the early Solar System. We present spectra of the Nightingale crater region on near-Earth asteroid Bennu with a distinct infrared absorption around 3.4 micrometers. Corresponding images of boulders show centimeters-thick, roughly meter-long bright veins. We interpret the veins as being composed of carbonates, similar to those found in aqueously altered carbonaceous chondrite meteorites. If the veins on Bennu are carbonates, fluid flow and hydrothermal deposition on Bennu's parent body would have occurred on kilometer scales for thousands to millions of years. This suggests large-scale, open-system hydrothermal alteration of carbonaceous asteroids in the early Solar System.

13.
Sci Adv ; 6(41)2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33033037

RESUMEN

Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high-thermal inertia band at Bennu's equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.

14.
Sci Adv ; 6(41)2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33033036

RESUMEN

The gravity field of a small body provides insight into its internal mass distribution. We used two approaches to measure the gravity field of the rubble-pile asteroid (101955) Bennu: (i) tracking and modeling the spacecraft in orbit about the asteroid and (ii) tracking and modeling pebble-sized particles naturally ejected from Bennu's surface into sustained orbits. These approaches yield statistically consistent results up to degree and order 3, with the particle-based field being statistically significant up to degree and order 9. Comparisons with a constant-density shape model show that Bennu has a heterogeneous mass distribution. These deviations can be modeled with lower densities at Bennu's equatorial bulge and center. The lower-density equator is consistent with recent migration and redistribution of material. The lower-density center is consistent with a past period of rapid rotation, either from a previous Yarkovsky-O'Keefe-Radzievskii-Paddack cycle or arising during Bennu's accretion following the disruption of its parent body.

15.
Science ; 370(6517)2020 11 06.
Artículo en Inglés | MEDLINE | ID: mdl-33033157

RESUMEN

Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu's moderately blue average color. Craters indicate that the time scale of these color changes is ~105 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.

16.
Sociol Relig ; 70(2)2009.
Artículo en Inglés | MEDLINE | ID: mdl-24353398

RESUMEN

Despite the increasing numbers of Americans who die in nursing homes (NHs) and residential care/assisted living (RC/AL) facilities, and the importance of religious and spiritual needs as one approaches death, little is known about how these needs are met for dying individuals in long-term care (LTC) institutional settings. This study compared receipt of religious and spiritual help in four types of LTC settings: NHs, smaller (<16 beds) RC/AL facilities, traditional RC/AL facilities, and new-model RC/AL facilities. Data were also available for religious affiliation of the facilities, size, and provision of religious and hospice services. Controlling for such factors, the importance of religion/spirituality to the decedent was the strongest predictor of the decedent's receipt of spiritual help. In addition, new-model RC/AL facilities were significantly more likely to provide help for religious and spiritual needs of decedent residents than other RC/AL types, but did not differ significantly from NHs.

17.
J. inborn errors metab. screen ; 12: e20230011, 2024. tab, graf
Artículo en Inglés | LILACS-Express | LILACS | ID: biblio-1534790

RESUMEN

Abstract Phenylketonuria (PKU) is an autosomal recessive defect affecting the metabolic pathway of phenylalanine (Phe), causing hyperphenylalaninemia and neurotoxicity. Diagnosis must occur in the neonatal period and treatment should begin as early as possible. Evidence implies that treatment adherence declines as age advances. The aim was to describe the diet of a subgroup of Chilean adults with PKU currently in follow-up. Fifty-three subjects (49% women) followed up between January 2021 to April 2023 were considered. The concentration of Phe (PheC) in dried blood spots measured by fluorometry and 24-hour dietary recalls were analyzed. The median PheC of the sample was 438µmol/L (interquartile range(IQR):351-585µmol/L). A protein intake of 1.35±0.3 gr/Kg/d was observed of which 87% came from the protein substitute without Phe. Participants had a median Phe intake of 459mg/d (IQR:327-976) and 13.1g/d of fiber intake. Most participants, 51% and 92% reported consuming fruits and vegetables, respectively, and 32% consumed Low-Protein foods. Regarding micronutrients, all participants exceeded 90% adequacy according to recommendations. For vitamin-D and vitamin-B12, 100% is provided by the protein substitute. According to our results, it is mandatory to establish transition programs toward adulthood, to constantly maintain good metabolic control, and to adapt diet therapy to their new lifestyle.

18.
Nat Astron ; 3(4): 332-340, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31360777

RESUMEN

Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of meters observed to date. In the visible and near-infrared (0.4 to 2.4 µm) Bennu's spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth.

19.
JIMD Rep ; 42: 71-77, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29288420

RESUMEN

Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive disease, caused by mutations in the Phenylalanine Hydroxylase (PAH) gene situated in chromosome 12q22-q24.2. This gene has 13 exons. To date, 991 mutations have been described. The genotype is one of the main factors that determine the phenotype of this disease. OBJECTIVE: Characterize PKU genotype and phenotype seen in Chilean PKU patients. METHODS: We studied the PAH gene by restriction fragment length polymorphism (RFLP) and/or sequencing techniques to identify pathogenic mutations in 71 PKU subjects. We classified the phenotype according to Guldberg predicted value. RESULTS: We identified 26 different mutations in 134 of the 142 alleles studied (94.4%), 88.7% of the subjects had biallelic pathogenic mutations while 11.3% had only one pathogenic mutation identified. Compound heterozygous represented 85.9% of the cases. Exon 7 included the majority of mutations (26.9%) and 50% of mutations were missense. The most frequent mutations were c.1066-11G > A, c.442-?_509+?del and p.Val388Met. The majority of subjects (52.3%) had the classic phenotype. CONCLUSIONS: The most frequent mutations in our Chilean PKU population were p.Val388Met, c.442?_509+?del and c.1066-11G > A. It is possible to predict phenotype by detecting the genotype, and use this information to determine disease prognosis and adjust patient's medical and nutritional management accordingly.

20.
J Geophys Res Planets ; 122(12): 2510-2543, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-29497589

RESUMEN

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by visible/near-infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or H2O- or OH-bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe, S, and Cl enriched with low Si and adsorbed and structural H2O.

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