Context. Phyllosilicates were definitely identified on Mars by the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument onboard the Mars Express spacecraft. The ...identification, characterization, and mapping of deposits of these minerals hold clues to the potential past habitability. They also constitute a key element in planning for future landing sites. Aims. To infer the environmental conditions that existed at the time of the formation of these minerals, it is critical to determine if and how the composition of the deposits vary in space and time. Methods. We applied radiative transfer modeling to the OMEGA reflectance spectra to derive the modal mineralogy (mineral abundances) of some phyllosilicate-rich deposits. Results. In many outcrops, including the large areas in Nili Fossae, the surface mineralogy is dominated by primary non-altered minerals, with minor fractions of phyllosilicates. These assemblages could result from hydrothermal alteration. By contrast, deposits in the Mawrth Vallis region exhibit a large content of hydrated phyllosilicates, which suggests that the rocks may be mature sedimentary rocks or altered volcanics. Evidence of alteration resulting from metamorphism due to an impact is reported in the central peak of a crater.
With its smaller size, well-known boundary conditions, and the availability of detailed bathymetric data, Lake Geneva’s subaquatic canyon in the Rhone Delta is an excellent analogue to understand ...sedimentary processes in deep-water submarine channels. A multidisciplinary research effort was undertaken to unravel the sediment dynamics in the active canyon. This approach included innovative coring using the Russian MIR submersibles, in situ geotechnical tests, and geophysical, sedimentological, geochemical and radiometric analysis techniques. The canyon floor/levee complex is characterized by a classic turbiditic system with frequent spillover events. Sedimentary evolution in the active canyon is controlled by a complex interplay between erosion and sedimentation processes. In situ profiling of sediment strength in the upper layer was tested using a dynamic penetrometer and suggests that erosion is the governing mechanism in the proximal canyon floor while sedimentation dominates in the levee structure. Sedimentation rates progressively decrease down-channel along the levee structure, with accumulation exceeding 2.6 cm/year in the proximal levee. A decrease in the frequency of turbidites upwards along the canyon wall suggests a progressive confinement of the flow through time. The multi-proxy methodology has also enabled a qualitative slope-stability assessment in the levee structure. The rapid sediment loading, slope undercutting and over-steepening, and increased pore pressure due to high methane concentrations hint at a potential instability of the proximal levees. Furthermore, discrete sandy intervals show very high methane concentrations and low shear strength and thus could correspond to potentially weak layers prone to scarp failures.
The Mawrth Vallis region contains an extensive (at least 300
km
×
400
km) and thick (⩾300
m), finely layered (at meter scale), clay-rich unit detected by OMEGA. We use OMEGA, HRSC DTMs derived from ...stereoscopic imagery, HRSC color imagery and high resolution imagery such as MOC, CTX and HiRISE to characterize the geometry and the composition of the clay-rich unit at the regional scale. Our results show that the clay-bearing unit can be divided into sub-units on the basis of differences in color and composition. In false-color visible imagery, alternating white/bluish and orange/red colored units correspond to a compositional succession of, respectively, Al- and Fe- or Mg-phyllosilicate rich material. Geological cross-sections are presented along the principal outcrops of the region in order to define the stratigraphy of these sub-units. This method shows that the dips of the sub-units are frequently close to the slopes of the present topography, except for scarps visible at the dichotomy boundary, inside impact craters walls, and outcrops inside Mawrth Vallis. In addition to the Al- and Fe- or Mg-phyllosilicate rich sub-units, an altered surface is identified as the lower basement unit. We propose two possible end-member scenarios to explain the derived stratigraphy: (1) alteration of volcaniclastic, aeolian or aqueous layered deposits of various compositions by groundwater, resulting in distinct altered rocks; or (2) Alteration coeval with the deposition of sediments under varying chemical conditions, in wet pedodiagenetic environment.
The Mawrth Vallis area displays some of the largest phyllosilicate-rich outcrops of Mars, on Noachian highlands. The Mawrth Vallis region is located just at the dichotomy boundary between the ...Noachian highlands and the younger, northern lowlands. A large, thick, layered clay-rich unit is present throughout the inter-crater plateaus. Clay-rich layers have also been identified in parts of the Mawrth Vallis and Oyama crater floors. The age of the alteration and its relationships with other processes such as fluvial activity is fundamental for estimating the timing of aqueous activity and habitability in this region, and on Mars. We have investigated the relative stratigraphy and ages of the regional plateau, of key surfaces of the inter-crater plateau, of Oyama crater's floor and of Chryse Planitia deposits in Mawrth Vallis' mouth to constrain the age of the clay unit and its alteration. According to the cratering model results, the main layered unit may have started forming prior to ∼4.0Ga ago, was largely deposited by ∼3.9Ga ago, and suffered erosion and redeposition up to ∼3.8Ga ago, as indicated by the latest age of the deposits on the floor of Oyama crater. Surface aqueous alteration stopped no later than 3.7–3.6Ga ago, corresponding to the age of the dark, non-altered material capping the region, and of the dark deposits in Mawrth Vallis' mouth. This work provides useful boundaries for constraining the time period of surface or shallow sub-surface water activity in this region. This preserved window into early phases of aqueous activity on Mars gives us a unique opportunity to study an aqueous environment of exobiological interest in the early solar system.
► The Mawrth Vallis region of Mars is studied through analysis of regional stratigraphy. ► Key surfaces are dated based on crater retention ages. ► Deposition of layers began ∼4.0Ga ago, until 3.8Ga with redeposition in Oyama crater. ► Aqueous alteration on the surface ended >3.7Ga ago. ► Mawrth Vallis provides an exceptional preserved window into the aqueous activity of the early Mars.
Pandemic-related life changes may have had a deleterious impact on suicidal behaviours. Early detection of suicidal ideation and identification of subgroups at increased risk could help prevent ...suicide, one of the leading causes of death among adolescents worldwide. Here, we aimed to investigate the prevalence of and risk factors for suicidal ideation in adolescents using a population-based sample from Switzerland, two years into the pandemic.
Between December 2021 and June 2022, adolescents aged 14 to 17 years already enrolled in a population-based cohort study (State of Geneva, Switzerland) were asked about suicidal ideation over the previous year. In addition to a regression model, we conducted a network analysis of exposures which identified direct and indirect risk factors for suicidal ideation (i.e. those connected through intermediate risk factors) using mixed graphical models.
Among 492 adolescents, 14.4% (95% CI: 11.5-17.8) declared having experienced suicidal ideation over the previous year. Using network analysis, we found that high psychological distress, low self-esteem, identifying as lesbian, gay or bisexual, suffering from bullying, extensive screen time and a severe COVID-19 pandemic impact were major risk factors for suicidal ideation, with parent-adolescent relationship having the highest centrality strength in the network.
Our results show that a significant proportion of adolescents experience suicidal ideation, yet these rates are comparable with pre-pandemic results. Providing psychological support is fundamental, with a focus on improving parent-adolescent relationships.
Infections are common in nursing home (NH) residents with advanced dementia but are often managed inappropriately. Antimicrobials are extensively prescribed, but frequently with insufficient evidence ...to support a bacterial infection, promoting the emergence of multidrug-resistant organisms. Moreover, the benefits of antimicrobials remain unclear in these seriously ill residents for whom comfort is often the goal of care. Prior NH infection management interventions evaluated in randomized clinical trials (RCTs) did not consider patient preferences and lack evidence to support their effectiveness in 'real-world' practice.
This report presents the rationale and methodology of TRAIN-AD (Trial to reduce antimicrobial use in nursing home residents with Alzheimer's disease and other dementias), a parallel group, cluster RCT evaluating a multicomponent intervention to improve infection management for suspected urinary tract infections (UTIs) and lower respiratory tract infections (LRIs) among NH residents with advanced dementia. TRAIN-AD is being conducted in 28 facilities in the Boston, USA, area randomized in waves using minimization to achieve a balance on key characteristics (N = 14 facilities/arm). The involvement of the facilities includes a 3-month start-up period and a 24-month implementation/data collection phase. Residents are enrolled during the first 12 months of the 24-month implementation period and followed for up to 12 months. Individual consent is waived, thus almost all eligible residents are enrolled (target sample size, N = 410). The intervention integrates infectious disease and palliative care principles and includes provider training delivered through multiple modalities (in-person seminar, online course, management algorithms, and prescribing feedback) and an information booklet for families. Control facilities employ usual care. The primary outcome, abstracted from the residents' charts, is the number of antimicrobial courses prescribed for UTIs and LRIs per person-year alive.
TRAIN-AD is the first cluster RCT testing a multicomponent intervention to improve infection management in NH residents with advanced dementia. Its findings will provide an evidence base to support the benefit of a program addressing the critical clinical and public health problem of antimicrobial misuse in these seriously ill residents. Moreover, its hybrid efficacy-effectiveness design will inform the future conduct of cluster RCTs evaluating nonpharmacological interventions in the complex NH setting in a way that is both internally valid and adaptable to the 'real-world'.
ClinicalTrials.gov, NCT03244917 . Registered on 10 August 2017.
The medium-term impact of the COVID-19 pandemic on the wellbeing of children and adolescents remains unclear. More than 2 years into the pandemic, we aimed to quantify the frequency and determinants ...of having been severely impacted by the COVID-19 pandemic and estimate its impact on health-related quality of life (HRQoL) and mental health.
Data was drawn from a population-based cohort of children and adolescents, recruited between December 2021 and June 2022, in Geneva, Switzerland. The Coronavirus impact scale was used to assess the multidimensional impact of the pandemic on children through parent's report. A score higher than one standard deviation above the mean was deemed a severe impact. Parents additionally reported about their offspring HRQoL and mental health with validated scales. Determinants of having been severely impacted were assessed with logistic models, as were the associations between having experienced a severe impact and poor HRQoL or mental health.
Out of 2101 participants aged 2-17, 12.7% had experienced a severe pandemic impact. Having a lasting health condition, a pandemic-related worsening of lifestyle habits or an unfavorable family environment were associated with having been severely impacted by the pandemic, while a previous anti-SARS-CoV-2 infection was not. Participants who had experienced a severe pandemic impact were more likely to present poor HRQoL (aOR = 3.1; 95% CI 2.3-4.4) and poor mental health (aOR = 3.9; 95% CI 2.5-6.2).
The COVID-19 pandemic may have persistent consequences on the wellbeing of children and adolescents, especially among those with health and family vulnerabilities.
The Mawrth Vallis region is covered by some of the largest phyllosilicate‐rich outcrops on Mars, making it a unique window into the past history of Mars in terms of water alteration, potential ...habitability, and the search for past life. A landing ellipse had been proposed for the Curiosity rover. This area has been extensively observed by the High Resolution Imaging Science Experiment and the Compact Reconnaissance Imaging Spectrometer for Mars, offering the possibility to produce geologic, structural, and topographic maps at very high resolution. These observations provide an unprecedented detailed context of the rocks at Mawrth Vallis, in terms of deposition, alteration, erosion, and mechanical constraints. Our analyses demonstrate the presence of a variety of alteration environments on the surface and readily accessible to a rover, the presence of flowing water at the surface postdating the formation of the clay‐rich units, and evidence for probable circulation of fluids in the rocks at different depths. These rocks undergo continuous erosion, creating fresh outcrops where potential biomarkers may have been preserved. The diversity of aqueous environments over geological time coupled to excellent preservation properties make the area a very strong candidate for future robotic investigation on Mars, like the NASA Mars 2020 mission.
Key Points
High‐resolution data enable high‐precision geological mapping at Mawrth Vallis
Mapping shows the variety of depositional and alteration environments
Highlights the interest of Mawrth Vallis as a future landing site
The purpose of this study was to assess the value of the fetal middle cerebral artery peak systolic velocity in the prediction of anemia within 24 hours of the death of one monochorionic twin in ...twin-to-twin-transfusion syndrome and to establish the correlation between middle cerebral artery peak systolic velocity and hemoglobin concentration in fetuses who are at risk for acute anemia.
Doppler examination of the middle cerebral artery peak systolic velocity was performed in 20 monochorionic survivors of pregnancies that were complicated by twin-to-twin-transfusion syndrome that occurred between 20 and 34 weeks of gestation. Doppler examination was performed before cordocentesis and after intrauterine transfusion when appropriate. Both hemoglobin concentration and middle cerebral artery peak systolic velocity were expressed in multiples of the median. Severe anemia was defined as hemoglobin concentration of <0.55 multiples of the median, and we used the cutoff point of 1.50 times the median values at any gestational age to calculate the sensitivity and specificity of middle cerebral artery peak systolic velocity in detecting moderate or severe anemia.
Fetal anemia was confirmed in 10 of 20 fetuses. We performed seven intrauterine transfusions. The sensitivity and specificity of middle cerebral artery peak systolic velocity in the prediction of severe fetal anemia were of 90%, with a false-negative rate of 10%. The correlation between peak systolic velocity and hemoglobin concentration both before and after transfusion was evaluated by regression analysis and was strongly significant.
In fetuses who are at risk of acute anemia, the measurement of middle cerebral artery peak systolic velocity was found to be a reliable noninvasive diagnostic tool and may be helpful in counseling and planning invasive assessment.
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