The lunar surface is ancient and well-preserved, recording Solar System history and planetary evolution processes. Ancient basin-scale impacts excavated lunar mantle rocks, which are still expected ...to be present on the surface. Sampling these rocks would provide insight into fundamental planetary processes, including differentiation and magmatic evolution. There is contention among lunar scientists as to what lithologies make up the upper lunar mantle, and where they may have been exposed on the surface. We review dynamical models of lunar differentiation in the context of recent experiments and spacecraft data, assessing candidate lithologies, their distribution, and implications for lunar evolution.
Hydrogen bonding underpins the properties of a vast array of systems spanning a wide variety of scientific fields. From the elegance of base pair interactions in DNA to the symmetry of extended ...supramolecular assemblies, hydrogen bonds play an essential role in directing intermolecular forces. Yet fundamental aspects of the hydrogen bond continue to be vigorously debated. Here we use dynamic force microscopy (DFM) to quantitatively map the tip-sample force field for naphthalene tetracarboxylic diimide molecules hydrogen-bonded in two-dimensional assemblies. A comparison of experimental images and force spectra with their simulated counterparts shows that intermolecular contrast arises from repulsive tip-sample interactions whose interpretation can be aided via an examination of charge density depletion across the molecular system. Interpreting DFM images of hydrogen-bonded systems therefore necessitates detailed consideration of the coupled tip-molecule system: analyses based on intermolecular charge density in the absence of the tip fail to capture the essential physical chemistry underpinning the imaging mechanism.
“Mafic Mound” is a distinctive and enigmatic feature 75 km across and 1 km high near the center of the vast South Pole‐Aitken Basin (SPA). Using several modern data sets, we characterize the ...composition, morphology, and gravity signature of the structure in order to assess its origin. Mafic Mound is found to exhibit a perched circular depression and a homogeneous high‐Ca pyroxene‐bearing composition. Several formation hypotheses based on known lunar processes are evaluated, including the possibilities that Mafic Mound represents (1) uplifted mantle, (2) SPA‐derived impact melt, (3) a basalt‐filled impact crater, or (4) a volcanic construct. Individually, these common processes cannot fully reproduce the properties of Mafic Mound. Instead, we propose a hybrid origin in which Mafic Mound is an edifice formed by magmatic processes induced by the formation and evolution of SPA. This form of nonmare volcanism has not previously been documented on the Moon.
Key Points
Mafic Mound in central SPA is 75 km across, 1 km high, and rich in high‐Ca pyroxene
New observations (composition, topography, and gravity) strongly suggest an extrusive magmatic origin
The proposed magma source is related to the formation and evolution of SPA
To conduct comparative cost analysis of hospital care for critically ill patients with Limited English Proficiency (LEP) versus patients with English proficiency (controls).
We conducted a historical ...cohort study using propensity matching at Mayo Clinic Rochester, a quaternary care academic center. We included hospitalized patients who had at least one admission to ICU during a 10-year period between 1/1/2008-12/31/2017.
Due to substantial differences in baseline characteristics of the groups, propensity matching for the covariates age, sex, race, ethnicity, APACHE 3 score, and Charlson Comorbidity score was used, and we achieved the intended balance. The final cohort included 80,404 patients, 4,246 with LEP and 76,158 controls. Patients with LEP had higher costs during hospital admission to discharge, with a mean cost difference of $3861 (95% CI $822 to $6900, p = 0.013) and also higher costs during index ICU admission to hospital discharge, with a mean cost difference of $3166 (95% CI $231 to $6101, p = 0.035). A propensity matched cohort including only those that survived showed those with LEP had significantly greater mean costs for all outcomes. Sensitivity analysis revealed that international patients with LEP had significantly greater overall hospital costs of $9,240 than patients with LEP who resided in the US (95% CI $3341 to $15,140, p = 0.002).
This is the first study to demonstrate significantly higher costs for patients with LEP experiencing a critical illness. The causes for this may be increased healthcare utilization secondary to communication deficiencies that impede timely decision making about care.
Data on failure to rescue (FTR) after esophagectomy are sparse. We sought to better understand the patient factors associated with FTR and to assess whether FTR is associated with hospital volume.
We ...identified all patients undergoing esophagectomy between 2010 and 2014 from the Agency for Healthcare Research and Quality Nationwide Readmission Database. We defined FTR as mortality after a major complication. Multiple logistic regression was used to identify patient factors and hospital-volume associations with FTR.
Of 26,820 patients undergoing an esophagectomy, 7130 (26.6%) experienced a major complication. Of those, 1321 did not survive the index hospitalization (FTR rate, 18.5%). Risk factors for FTR included increasing age (adjusted odds ratio aOR, 1.06; P < .001), congestive heart failure (aOR, 2.07; P < .001), bleeding disorders (aOR, 2.9; P < .001), liver disease (aOR, 2.37; P = .001), and renal failure (aOR, 2.37; P = .002). At the hospital level there was wide variation in FTR rates across hospital volume quintiles, with 21.2% of patients suffering a complication not surviving to discharge at low-volume hospitals compared with 13.4% at high-volume hospitals (P < .001). At low-volume hospitals the highest FTR rates were acute renal failure (35.3%), postoperative hemorrhage (31.9%), and pulmonary failure (28.1%).
One in 5 esophagectomy patients suffering a complication at low-volume hospitals do not survive to discharge. Several patient factors are associated with death after a major complication. Strategies to improve the recognition and management of complications in at-risk patients may be essential to improve outcomes at low-volume hospitals.
We reexamine the relationship between pyroxene composition and near‐infrared absorption bands, integrating measurements of diverse natural and synthetic samples. We test an algorithm (PLC) involving ...a two‐part linear continuum removal and parabolic fits to the 1 and 2 μm bands—a computationally simple approach which can easily be automated and applied to remote sensing data. Employing a suite of synthetic pure pyroxenes, the PLC technique is shown to derive similar band centers to the modified Gaussian model. PLC analyses are extended to natural pyroxene‐bearing materials, including (1) bulk lunar basalts and pyroxene separates, (2) diverse lunar soils, and (3) HED meteorites. For natural pyroxenes, the relationship between composition and absorption band center differs from that of synthetic pyroxenes. These differences arise from complexities inherent in natural materials such as exsolution, zoning, mixing, and space weathering. For these reasons, band center measurements of natural pyroxene‐bearing materials are compositionally nonunique and could represent three distinct scenarios (1) pyroxene with a narrow compositional range, (2) complexly zoned pyroxene grains, or (3) a mixture of multiple pyroxene (or nonpyroxene) components. Therefore, a universal quantitative relationship between band centers and pyroxene composition cannot be uniquely derived for natural pyroxene‐bearing materials without additional geologic context. Nevertheless, useful relative relationships between composition and band center persist in most cases. These relationships are used to interpret M3 data from the Humboldtianum Basin. Four distinct compositional units are identified (1) Mare Humboldtianum basalts, (2) distinct outer basalts, (3) low‐Ca pyroxene‐bearing materials, and (4) feldspathic materials.
Background
Adult onset idiopathic isolated focal dystonia presents with a number of phenotypes. Reported prevalence rates vary considerably; well‐characterized cohorts are important to our ...understanding of this disorder.
Aim
To perform a nationwide epidemiological study of adult onset idiopathic isolated focal dystonia in the Republic of Ireland.
Methods
Patients with adult onset idiopathic isolated focal dystonia were recruited from multiple sources. Diagnosis was based on assessment by a neurologist with an expertise in movement disorders. When consent was obtained, a number of clinical features including family history were assessed.
Results
On the prevalence date there were 592 individuals in Ireland with adult onset idiopathic isolated focal dystonia, a point prevalence of 17.8 per 100 000 (95% confidence interval 16.4−19.2). Phenotype numbers were cervical dystonia 410 (69.2%), blepharospasm 102 (17.2%), focal hand dystonia 39 (6.6%), spasmodic dysphonia 18 (3.0%), musician's dystonia 17 (2.9%) and oromandibular dystonia six (1.0%). Sixty‐two (16.5%) of 375 consenting index cases had a relative with clinically confirmed adult onset idiopathic isolated focal dystonia (18 multiplex and 24 duplex families). Marked variations in the proportions of patients with tremor, segmental spread, sensory tricks, pain and psychiatric symptoms by phenotype were documented.
Conclusions
The prevalence of adult onset idiopathic isolated focal dystonia in Ireland is higher than that recorded in many similar service‐based epidemiological studies but is still likely to be an underestimate. The low proportion of individuals with blepharospasm may reflect reduced environmental exposure to sunlight in Ireland. This study will serve as a resource for international comparative studies of environmental and genetic factors in the pathogenesis of the disorder.
Poly(vinyl acetate) (PVAc) copolymer latex-based composites were prepared with multi-walled carbon nanotubes (MWCNT), stabilized with sodium deoxycholate (DOC) or meso-tetra(4-carboxyphenyl) porphine ...(TCPP). SEM images show that a segregated MWCNT network developed during drying, which resulted in relatively low percolation thresholds (1.62 and 2.17
wt.% MWCNT for DOC and TCPP, respectively). The electrical conductivity (
σ) of TCPP-stabilized composites is very similar to that of DOC-stabilized, while the thermopower (or Seebeck coefficient (
S)) is five times as large. This enhanced thermopower suggests the MWCNT:TCPP/PVAc composite will have an order of magnitude greater power factor (
S
2
σ), which is an important measure of efficiency for thermoelectric materials (i.e., materials capable of converting a thermal gradient to a voltage). The thermal conductivity of these composites remains comparable to typical polymeric materials due to numerous tube–tube connections that act as phonon scattering centers. The universality of this approach was confirmed using much more electrically conductive double-walled carbon nanotube-filled composites that showed similar improvement with TCPP stabilization. It is possible that other porphyrin derivatives, or semiconducting molecules capable of stabilizing nanotubes in water, could be used to further enhance the Seebeck coefficient and improve the ability of these composites to convert waste heat into electricity.
Context.
The response of imaging atmospheric Cherenkov telescopes to incident
γ
-ray-initiated showers in the atmosphere changes as the telescopes age due to exposure to light and weather. These ...aging processes affect the reconstructed energies of the events and
γ
-ray fluxes.
Aims.
This work discusses the implementation of signal calibration methods for the Very Energetic Radiation Imaging Telescope Array System (VERITAS) to account for changes in the optical throughput and detector performance over time.
Methods.
The total throughput of a Cherenkov telescope is the product of camera-dependent factors, such as the photomultiplier tube gains and their quantum efficiencies, and the mirror reflectivity and Winston cone response to incoming radiation. This document summarizes different methods to determine how the camera gains and mirror reflectivity have evolved over time and how we can calibrate this changing throughput in reconstruction pipelines for imaging atmospheric Cherenkov telescopes. The implementation is validated against seven years of observations with the VERITAS telescopes of the Crab Nebula, which is a reference object in very-high-energy astronomy.
Results.
Regular optical throughput monitoring and the corresponding signal calibrations are found to be critical for the reconstruction of extensive air shower images. The proposed implementation is applied as a correction to the signals of the photomultiplier tubes in the telescope simulation to produce fine-tuned instrument response functions. This method is shown to be effective for calibrating the acquired
γ
-ray data and for recovering the correct energy of the events and photon fluxes. At the same time, it keeps the computational effort of generating Monte Carlo simulations for instrument response functions affordably low.
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