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Background: Given the large number of readout pixels in clinical positron emission tomography (PET) scanners, signal multiplexing is an indispensable feature to reduce scanner complexity, power consumption, heat output, and cost. Purpose: In this paper, we introduce interleaved multiplexing (iMux) scheme that utilizes the characteristic light‐sharing pattern of depth‐encoding Prism‐PET detector modules with single‐ended readout. Methods: In the iMux readout, four anodes from every other silicon photomultiplier (SiPM) pixels across rows and columns, which overlap with four distinct light guides, are connected to the same application‐specific integrated circuit (ASIC) channel. The 4‐to‐1 coupled Prism‐PET detector module was used which consisted of a 16 × 16 array of 1.5 × 1.5 × 20 mm3 lutetium yttrium oxyorthosilicate (LYSO) scintillator crystals coupled to an 8 × 8 array with 3 × 3 mm2 SiPM pixels. A deep learning‐based demultiplexing model was investigated to recover the encoded energy signals. Two different experiments were performed with non‐multiplexed and multiplexed readouts to evaluate the spatial, depth of interaction (DOI), and timing resolutions of our proposed iMux scheme. Results: The measured flood histograms, using the decoded energy signals from our deep learning‐based demultiplexing architecture, achieved perfect crystal identification of events with negligible decoding error. The average energy, DOI, and timing resolutions were 9.6 ± 1.5%, 2.9 ± 0.9 mm, and 266 ± 19 ps for non‐multiplexed readout and 10.3 ± 1.6%, 2.8 ± 0.8 mm, and 311 ± 28 ps for multiplexed readout, respectively. Conclusions: Our proposed iMux scheme improves on the already cost‐effective and high‐resolution Prism‐PET detector module and provides 16‐to‐1 crystal‐to‐readout multiplexing without appreciable performance degradation. Also, only four SiPM pixels are shorted together in the 8 × 8 array to achieve 4‐to‐1 pixel‐to‐readout multiplexing, resulting in lower capacitance per multiplexed channel. [ABSTRACT FROM AUTHOR]

Background: Positron emission tomography (PET) has had a transformative impact on oncological and neurological applications. However, still much of PET's potential remains untapped with limitations primarily driven by low spatial resolution, which severely hampers accurate quantitative PET imaging via the partial volume effect (PVE). Purpose: We present experimental results of a practical and cost‐effective ultra‐high resolution brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detectors arranged along a compact and conformal gantry, showing substantial reduction in PVE and accurate radiotracer uptake quantification in small regions. Methods: The decagon‐shaped prototype scanner has a long diameter of 38.5 cm, a short diameter of 29.1 cm, and an axial field‐of‐view (FOV) of 25.5 mm with a single ring of 40 Prism‐PET detector modules. Each module comprises a 16 × 16 array of 1.5 × 1.5 × 20‐mm3 lutetium yttrium oxyorthosillicate (LYSO) scintillator crystals coupled 4‐to‐1 to an 8 × 8 array of silicon photomultiplier (SiPM) pixels on one end and to a prismatoid light guide array on the opposite end. The scanner's performance was evaluated by measuring depth‐of‐interaction (DOI) resolution, energy resolution, timing resolution, spatial resolution, sensitivity, and image quality of ultra‐micro Derenzo and three‐dimensional (3D) Hoffman brain phantoms. Results: The full width at half maximum (FWHM) DOI, energy, and timing resolutions of the scanner are 2.85 mm, 12.6%, and 271 ps, respectively. Not considering artifacts due to mechanical misalignment of detector blocks, the intrinsic spatial resolution is 0.89‐mm FWHM. Point source images reconstructed with 3D filtered back‐projection (FBP) show an average spatial resolution of 1.53‐mm FWHM across the entire FOV. The peak absolute sensitivity is 1.2% for an energy window of 400−650 keV. The ultra‐micro Derenzo phantom study demonstrates the highest reported spatial resolution performance for a human brain PET scanner with perfect reconstruction of 1.00‐mm diameter hot‐rods. Reconstructed images of customized Hoffman brain phantoms prove that Prism‐PET enables accurate radiotracer uptake quantification in small brain regions (2–3 mm). Conclusions: Prism‐PET will substantially strengthen the utility of quantitative PET in neurology for early diagnosis of neurodegenerative diseases, and in neuro‐oncology for improved management of both primary and metastatic brain tumors. [ABSTRACT FROM AUTHOR]

Melt from debris‐covered glaciers represents a regionally important freshwater source, especially in high‐relief settings as found in central Asia, Alaska, and South America. Sub‐debris melt is traditionally predicted from surface energy balance models that determine heat conduction through the supraglacial debris layer. Convection is rarely addressed, despite the porous nature of debris. Here we provide the first constraints on convection in supraglacial debris, through the development of a novel method to calculate individual conductive and nonconductive heat flux components from debris temperature profile data. This method was applied to data from Kennicott Glacier, Alaska, spanning two weeks in the summer of 2011 and two months in the summer of 2020. Both heat flux components exhibit diurnal cycles, the amplitude of which is coupled to atmospheric conditions. Mean diurnal nonconductive heat flux peaks at up to 43% the value of conductive heat flux, indicating that failure to account for it may lead to an incorrect representation of melt rates and their drivers. We interpret this heat flux to be dominated by latent heat as debris moisture content changes on a diurnal cycle. A sharp afternoon drop‐off in nonconductive heat flux is observed at shallow depths as debris dries. We expect these processes to be relevant for other debris‐covered glaciers. Debris properties such as porosity and tortuosity may play a large role in modulating it. Based on the present analysis, we recommend further study of convection in supraglacial debris for glaciers across the globe with different debris properties. Plain Language Summary: Glacier melt under a surface layer of rocky debris is typically predicted by determining the energy available at the debris surface, then calculating heat transferred via conduction through the debris layer. However, heat can also be transferred in the debris layer through other processes such as air movement and the evaporation of melt water. We analyzed temperature data in the debris to show that these processes are significant, accounting for up to 43% of heat transferred via conduction. These must thus be investigated further and incorporated into models of glacier melt. Key Points: We developed a new method to constrain supraglacial debris thermal properties and nonconductive heat fluxes from temperature profile dataNonconductive heat flux can be as much as 43% the conductive heat flux, thus it is important to understand its driving processesWe interpret nonconductive heat flux to be dominated by convection of moisture and latent heat flux as the debris diurnally wets and dries [ABSTRACT FROM AUTHOR]

Background: Anti-CD38 antibodies such as daratumumab (DARA) are critical therapies for multiple myeloma and other diseases. Unfortunately, anti-CD38 antibodies cause panreactivity in indirect antiglobulin tests (IATs), complicating blood compatibility testing. The anti-CD38 interference is most often mitigated by treating reagent red blood cells (RBCs) with dithiothreitol (DTT). However, when using the DTT method, not all RBC antibody specificities can be detected (e.g., anti-K), and the DTT method is impractical for some transfusion services. We evaluated the ability of a new anti-idiotype antibody to neutralize DARA in vitro and eliminate the anti-CD38 interference.Study Design and Methods: A recombinant monoclonal rabbit anti-DARA idiotype antibody ("anti-DARA") was generated. The ratio of anti-DARA required to neutralize DARA in spiked samples was evaluated in IATs performed in gel. IATs performed in tube were used to demonstrate that anti-DARA allows alloantibody detection in the presence of DARA. Plasma samples from 29 patients receiving DARA were treated with a fixed quantity of anti-DARA (120 μg) before performing antibody detection tests (screens) in tube.Results: Anti-DARA used at or above a 1:1 ratio with DARA eliminated the DARA interference with IATs. Anti-DARA allowed detection of both alloanti-E and alloanti-K in the presence of DARA. In 27/29 (93.1%) clinical samples, 120 μg anti-DARA was sufficient to neutralize the DARA in 100 μl patient plasma.Discussion: An anti-DARA:DARA ratio as low as 1:1 is sufficient to neutralize DARA in solution. A fixed amount of anti-DARA eliminates the anti-CD38 interference in most patient samples. [ABSTRACT FROM AUTHOR]

Purpose: Quantitative in vivo molecular imaging of fine brain structures requires high‐spatial resolution and high‐sensitivity. Positron emission tomography (PET) is an attractive candidate to introduce molecular imaging into standard clinical care due to its highly targeted and versatile imaging capabilities based on the radiotracer being used. However, PET suffers from relatively poor spatial resolution compared to other clinical imaging modalities, which limits its ability to accurately quantify radiotracer uptake in brain regions and nuclei smaller than 3 mm in diameter. Here we introduce a new practical and cost‐effective high‐resolution and high‐sensitivity brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detector modules arranged in a conformal decagon geometry, to substantially reduce the partial volume effect and enable accurate radiotracer uptake quantification in small subcortical nuclei. Methods: Two Prism‐PET brain scanner setups were proposed based on our 4‐to‐1 and 9‐to‐1 coupling of scintillators to readout pixels using 1.5×1.5×20$1.5 \times 1.5 \times 20$ mm3 and 0.987×0.987×20$0.987 \times 0.987 \times 20$ mm3 crystal columns, respectively. Monte Carlo simulations of our Prism‐PET scanners, Siemens Biograph Vision, and United Imaging EXPLORER were performed using Geant4 application for tomographic emission (GATE). National Electrical Manufacturers Association (NEMA) standard was followed for the evaluation of spatial resolution, sensitivity, and count‐rate performance. An ultra‐micro hot spot phantom was simulated for assessing image quality. A modified Zubal brain phantom was utilized for radiotracer imaging simulations of 5‐HT1A receptors, which are abundant in the raphe nuclei (RN), and norepinephrine transporters, which are highly concentrated in the bilateral locus coeruleus (LC). Results: The Prism‐PET brain scanner with 1.5 mm crystals is superior to that with 1 mm crystals as the former offers better depth‐of‐interaction (DOI) resolution, which is key to realizing compact and conformal PET scanner geometries. We achieved uniform 1.3 mm full‐width‐at‐half‐maximum (FWHM) spatial resolutions across the entire transaxial field‐of‐view (FOV), a NEMA sensitivity of 52.1 kcps/MBq, and a peak noise equivalent count rate (NECR) of 957.8 kcps at 25.2 kBq/mL using 450–650 keV energy window. Hot spot phantom results demonstrate that our scanner can resolve regions as small as 1.35 mm in diameter at both center and 10 cm away from the center of the transaixal FOV. Both 5‐HT1A receptor and norepinephrine transporter brain simulations prove that our Prism‐PET scanner enables accurate quantification of radiotracer uptake in small brain regions, with a 1.8‐fold and 2.6‐fold improvement in the dorsal RN as well as a 3.2‐fold and 4.4‐fold improvement in the bilateral LC compared to the Biograph Vision and EXPLORER, respectively. Conclusions: Based on our simulation results, the proposed high‐resolution and high‐sensitivity Prism‐PET brain scanner is a promising cost‐effective candidate to achieve quantitative molecular neuroimaging of small but important brain regions with PET clinically viable. [ABSTRACT FROM AUTHOR]

H2O formation during thermal decomposition of isopropanol was measured behind reflected shock waves at temperatures ranging from 1127 to 1621 K at an average pressure of 1.42 atm using a laser absorption technique. Of the five modern chemical kinetics models used to compare the H2O time histories, the model from Li et al (Combust. Flame 2019;207:171‐185) showed the best overall agreement. Sensitivity and rate of production analyses using the Li et al model (as well as those from AramcoMech 3.0, CRECK, and Togbe et al (Energy Fuel. 2011;25:676‐683)) showed unimolecular dehydration of isopropanol, iC3H7OH ⇌ H2O + C3H6 (R1), is nearly the sole reaction controlling H2O production at early times, allowing for an a priori measurement of the forward rate constant k1. The Arrhenius expression k1 (s–1) = 2.60 × 1013 exp(−31 120 K/T) was determined to represent best the data from this study. According to the models and previous experimental investigations, the pressure investigated is well within the high‐pressure limit (HPL) for this reaction. Additional, higher‐pressure experiments also confirmed the HPL assumption. An uncertainty analysis was performed by varying secondary reactions within their uncertainties and examining their effect on the overall prediction, establishing an uncertainty within ±20% for all but the highest temperature cases, which have a maximum uncertainty of ±40%. Experiments conducted with a radical trapper, toluene, showed little influence from radical chemistry, suggesting this estimated uncertainty is fairly conservative. Experimental data from Heyne et al (Z Phys Chem. 2015;229:881‐907) were found to be in good agreement with the rate measurements from this study and, therefore, a second Arrhenius expression, k1 (s–1) = 2.11 × 1013 exp(−30 820 K/T), was found to represent both datasets well. This second expression has a larger temperature range of 976‐1621 K. The present study provides the first high‐temperature data collected for this reaction, adding to the limited data available for isopropanol in the literature. [ABSTRACT FROM AUTHOR]

To understand the effects of the chemical structure of two C5 alkene isomers on their combustion properties, and to highlight the major chemical reactions occurring during their high‐temperature oxidation, water time histories were measured behind reflected shock waves for the oxidation of 1‐pentene (C5H10‐1) and 3‐methyl‐1‐butene (3M1B) in 99.5% Ar. The experiments were carried out at three different equivalence ratios (φ = 0.5, 1.0, and 2.0) at pressures and temperatures ranging from 1.29 to 1.47 atm and 1 331 to 1 877 K, respectively. The H2O quantification extends the database for 1‐pentene and provides new insights for 3M1B. These unique results were used to validate and to develop a new detailed kinetics model. Numerical predictions are presented, and the new model was able to capture the results with suitable accuracy, with 3M1B being notably more reactive than C5H10‐1. Sensitivity and rate‐of‐production analyses were performed to help explain the results. Under the present conditions, the reactivity is rapidly initiated by molecular dissociation of a fraction of the pentene isomers. The initiation phase then induces H‐atom abstraction by active radicals (H, OH, O, HO2, and CH3) to first produce alkenyl C5H9 radicals (or an alkyl radical and an alkenyl radical by breaking a C─C bond) and subsequent, smaller fragments. The difference in terms of reactivity between the isomers is essentially due to the fact that 3M1B has one particularly weak tertiary allylic C─H bond, which allows for fast H‐atom abstraction compared with 1‐pentene. [ABSTRACT FROM AUTHOR]

The development and refinement of NOx chemical kinetic mechanisms have been instrumental in understanding and reducing NOx formation. However, relatively little work has been performed with NOx species as the oxidizer, and such experiments can provide unique insights into NOx kinetics. Furthermore, speciation data can often provide useful information that complements global measurements such as ignition delay times in facilitating mechanism refinement. To provide such speciation data in the H2‐NO2 system, H2O measurements were performed using a fixed‐wavelength, direct absorption laser diagnostic near 1.39 µm behind reflected shock waves in fuel‐lean, near‐stoichiometric, and fuel‐rich mixtures of H2 and NO2 highly diluted in argon. Experiments were performed between 917 and 1782 K near atmospheric pressure. The H2O profiles obtained herein are markedly different from those using O2 as the oxidizer obtained in a previous study. The GRI 3.0 mechanism was found to greatly underestimate the H2O formation, whereas two modern mechanisms were found to predict the H2O formation quite accurately except at colder temperatures for fuel‐rich conditions. Explanations for the differences between these mechanisms are given and discussed, with the conclusion that older mechanisms such as GRI 3.0 should not be used to model hydrocarbon/NOx combustion chemistry as they are lacking several key reactions and species, namely NO3 and HONO. The discrepancy between models and data at lower temperatures could not be reconciled even when modifying two of the most‐sensitive reaction rates. To the best of the authors' knowledge, this study presents the first shock‐tube speciation study in the H2‐NO2 system. [ABSTRACT FROM AUTHOR]

The Middle Jurassic Todilto Member of the Wanakah Formation is a carbonate and gypsum unit inset into the underlying aeolian Entrada Sandstone in the San Juan Basin. Field and thin section study of the uppermost Entrada and Todilto at Ghost Ranch, New Mexico, identified Todilto facies and their relationship to remnant Entrada dune topography. Results support the previous interpretation that the Entrada dunes, housed in a basin below sea level, were rapidly flooded by marine waters. Mass wasting of the dunes gave rise to sediment‐gravity flows that largely buried remnant dune topography, leaving ca 12 m of relief that defined the antecedent condition for Todilto deposition. Previously interpreted as seasonal varves deposited in a stratified water body, the Todilto is reinterpreted as a microbial biolaminite. Most diagnostic are organic‐rich laminae with structures characteristic of filamentous microbes and containing trapped aeolian silt, and clotted‐texture laminae with a fabric associated with calcification of extracellular polymeric substances. The spatial arrangement of Todilto facies is controlled by the dune palaeotopography. A continuous basal laminated mudstone thickens over the dune crest, reflecting the optimum conditions for microbial mat development, and is interpreted to have been deposited when marine waters submerged the topography. Subsequent drying caused emergence of the crestal area, and formation of tepee structures and a dissolution breccia. Gypsiferous mudflats and periodic ponds occupied the dune flanks and interdune area, with gypsum concentrated within the interdune area. Entrada sands remained unstable during Todilto deposition with common injection structures into the Todilto, and a remnant slope caused the downslope movement and folding of Todilto strata on the upper lee face. Although some expansion of the gypsum occurred in the subsurface, facies architecture fostered development of a dissolution front adjacent to the interdune gypsum body with section collapse of gypsiferous limestone on the dune flanks. [ABSTRACT FROM AUTHOR]

Corn stover digestibility was enhanced via shock treatment. A slurry of lime-treated corn stover was placed in a partially filled closed vessel. From the ullage space, either a shotgun shell was fired into the slurry, or a gas mixture was detonated. Various conditions were tested (i.e., pressures, depth, solids concentrations, gas mixtures). A high pressurization rate (108,000 MPa/s shotgun shells; 4,160,000 MPa/s hydrogen/oxygen detonation) was the only parameter that improved enzymatic digestibility. Stoichiometric propane/air deflagration had a low pressurization rate (37.2 MPa/s) and did not enhance enzymatic digestibility. Without shock, enzymatic conversion of lime-treated corn stover was 0.80 g glucan digested/g glucan fed with an enzyme loading of 46.7 mg protein/g glucan. With shock, the enzyme loading was reduced by ∼2× while maintaining the same conversion. Detonations are extraordinarily fast; rapidly cycling three small vessels (0.575 m3 each) every 7.5 s enables commercially relevant shock treatment (2,000 tone/day). © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:815-823, 2017 [ABSTRACT FROM AUTHOR]

This study presents a comparison of commercially available titania nano-particles produced using electric wire explosion with nano-particles manufactured by the authors using a sol-gel synthesis process. For the present study, 20-nm titania was purchased off-the-shelf. It was determined to be rough spheres of 20 nm forming large, micron-sized agglomerates, whereas particles synthesized using the sol-gel process were found to be fundamentally 10 nm but with sub-micron agglomerations thereof. The nano-titania was added to 80% AP monomodal propellants at 0.3% and 1.0% by mass. Additional, 85% bimodal-AP mixtures were made, comparing commercial titania to the laboratory-synthesized particles at 1.0% by mass. Another set of samples compared a method of pre-mixing the synthesized additives directly into the binder material at 0.3% by mass of laboratory titania; two additional pre-mixed titania batches at 0.5% by mass were doped with either Fe or Cu into the nanocrystals. All propellants were tested up to 13.8 MPa at 3.8 MPa increments. Dry powder laboratory additives show a 60-to-100% increase in burning rate over the baseline samples with no catalyst and a 20-to-30% increase over the commercial nano-particles. Pre-mixed additives were found to produce similar burning rate increases but with lower concentrations required. This latest generation of particle synthesis techniques was further demonstrated in this study to have great potential for future propellant catalyst development. [ABSTRACT FROM AUTHOR]

Modern chemical synthesis techniques have allowed for improved incorporation of nano-scale additives into solid propellants. Various methods were implemented to incorporate titania nanoparticles into three representative ammonium perchlorate composite propellants (APCP), and the mechanical properties of each formulation were tested and compared to those of an analogous baseline. Advanced imaging techniques were applied to all particle synthesis methods to characterize particle size and particle network type and size. Uniaxial tensile testing was performed to measure propellant ultimate strength, ductility, and elastic modulus. In general, the addition of nano-titania additives to the propellant decreased propellant strength and modulus, but improved ductility. Propellant formulations containing in-situ titania exhibited an increase in ductility of 11 %, 286 %, and 186 % with a corresponding reduction in strength of 82 %, 52 %, and 17 % over analogous baselines. These trends corresponded to a simultaneous decrease in propellant density, indicating that when implementing nano-sized additives, care must be taken to monitor the effect of the altered manufacturing techniques on propellant physical properties in addition to just monitoring burning rates. Tailoring of propellant manufacturing procedures and the addition of Tepanol bonding agent to an in-situ APCP formulation fully recovered the propellant density and ultimate strength while retaining the enhanced ductility. [ABSTRACT FROM AUTHOR]

ABSTRACT Electronically excited carbon dioxide (CO2*) is known for its broadband emission, and its detection can lead to valuable information; however, owing to its broadband characteristics, CO2* is difficult to isolate experimentally, and its chemical kinetics are not well known. Although numerous works have monitored CO2* chemiluminescence, a full kinetic scheme for the excited species has yet to be developed. To this end, a series of shock-tube experiments was performed in H2-N2O-CO mixtures highly diluted in argon at conditions where emission from CO2* could be isolated and monitored. These results were used to evaluate the kinetics of CO2*, in particular the main CO2* formation reaction CO + O + M [ABSTRACT FROM AUTHOR]

Chemiluminescence from the OH(A → X) transition near 307 nm is a commonly used diagnostic in combustion applications such as flame chemistry, shock-tube experiments, and reacting-flow visualization. Although absolute measurements of OH(X) concentrations are well defined, there is no elementary relation between emission from the electronically excited state (OH*) and its absolute concentration. Thus, to enable quantitative emission measurements, a kinetics model has been assembled and optimized to predict OH* formation and quenching at combustion conditions. Shock-tube experiments were conducted in mixtures of H2/O2/Ar, CH4/O2/Ar, and CH4/H2/O2/Ar with high levels of argon dilution (>98%). Elementary reactions to model OH*, along with initial estimates of their rate coefficients, were taken from the literature. The important formation steps follow: R0R1 Sensitivity analyses were performed to identify experimental conditions under which the shape of the measured OH* profiles and the magnitude of the OH* emission would be sensitive to the formation reactions. A fitting routine was developed to express the formation rate parameters as a function of a single rate, k1 at the reference temperature (1490 K). With all rates so expressed, H2/CH4 mixtures were designed to uniquely determine the value of k1 at the reference temperature, from which the remaining rate parameters were calculated. Quenching rates were fixed at their literature values. The new model predicts the experimental data over the range of conditions studied and can be used to calibrate the emission diagnostic for other applications, such as measurements in real combustion environments, containing higher order hydrocarbon fuels and lower levels of dilution in air. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 714–724, 2006 [ABSTRACT FROM AUTHOR]

This article is the second in a series of two articles about the FOSSIL model, developed by Roger Naill and associates, to appear in the System Dynamics Review. "A System Dynamics Model for National Energy Policy Planning," published in issue 8:1, described the history and structure of FOSSIL and its use in the United States Department of Energy since 1978, In this article, the authors employ the model to explore a wide range of policy options intended to address the effects of energy use on global warming. [ABSTRACT FROM AUTHOR]

Lobate Debris Aprons (LDA) are martian landforms with a strong morphologic resemblance to rock glaciers and debris‐covered glaciers. While the Shallow Radar (SHARAD) sounder has confirmed that a handful of LDA are composed of >80% water ice, viscous flow morphology can also be produced by as little as 30% ice. To distinguish between these endmembers, we conducted a comprehensive regional SHARAD survey of LDA, in Deuteronilus Mensae. We found that the majority of LDA are penetrated by SHARAD and determined that they are composed of a material with ε′=3 and tanδ≈0.002 < 0.005. These LDA are thus consistently composed of >80% water ice, which constrains the regional sequestered ice budget to a minimum of 0.9 − 1.0 × 105 km3 or a 62–69‐cm Global Equivalent Layer. Plain Language Summary: Lobate debris aprons (LDA) are dust and rock‐covered Martian landforms thought to contain buried water ice due to their resemblance to creeping permafrost and debris‐covered glaciers. Their ice content has been the subject of debate; it may be as low as 30% or nearly pure ice. Understanding LDA composition and its variability across Mars is important for exploring climate history and investigating the feasibility of these features as water reservoirs for potential manned missions. The Shallow Radar (SHARAD) instrument on Mars Reconnaissance Orbiter can probe the interior of LDA, constraining their ice content. This has been demonstrated for individual LDA, which were shown to be composed of >80% water ice; however, no regional survey has been made to determine if these LDA are outliers or the norm. We present a survey of LDA composition constrained by SHARAD for the region of Deuteronilus Mensae—a region with abundant, widespread LDA. We found that 87% of LDA were penetrated by SHARAD and that these all had radar properties broadly consistent with high purity (80–90%) water ice. Combining these results with previous LDA volume mapping constrains their water ice content to 4 times the combined volume of the Great Lakes. Key Points: We present a comprehensive orbital radar sounding survey of lobate debris aprons in Deuteronilus and Protonilus MensaeThe dielectric properties of penetrated aprons are consistent with a high purity (>80%) water ice composition; these aprons are debris‐covered glaciersThe volume of ice in aprons confirmed to be glaciers is 0.9‐1.0 × 105 km3 or a 0.6‐0.7‐m Global Equivalent Layer [ABSTRACT FROM AUTHOR]