Effect Of Depth Research Articles

Ti4Ir2O : A time reversal invariant fully gapped unconventional superconductor

Here we report muon spin rotation (μSR) experiments on the temperature and field dependence of the effective magnetic penetration depth λ(T) in the η-carbide-type suboxide Ti4Ir2O, a superconductor with a considerably high upper critical field. The temperature dependence of λ(T), obtained from transverse-field (TF)-μSR measurements, is in perfect agreement with an isotropic fully gaped superconducting state. Furthermore, our ZF μSR results confirm that the time-reversal symmetry is preserved in the superconducting state. We find, however, a remarkably small ratio of Tc/λ0−2∼1.22. This value is close to most unconventional superconductors, showing that a very small superfluid density is present in the superconducting state of Ti4Ir2O. The presented results will pave the way for further theoretical and experimental investigations to obtain a microscopic understanding of the origin of such a high upper critical field in an isotropic single-gap superconducting system. Published by the American Physical Society 2024

Growth Response of Kappaphycus Alvarezii at Different Depth in the Waters of Batu Bao, East Nusa Tenggara

ABSTRACT Seaweed is one of the important fisheries commodities with significant economic value. Kappaphycus alvarezii, commonly known as Eucheuma cottoni in the market, is a type of seaweed that produces kappa carrageenan. This research aims to determine the effective planting depth for the growth, morphological and histological changes, and the environmental parameters influencing the growth of K. alvarezii. The cultivation method used in this research is the longline method, and it employs a Completely Randomized Design consisting of four treatments: 15cm, 30cm, 45cm, and 60cm, with each treatment replicated five times. The data were analyzed using analysis of variance, and if significant differences were found, Duncan's post hoc test was conducted. The research results indicate that an increase in planting depth has a significant impact on specific growth rate (SGR) and average growth rate (AGR). Deeper planting depths result in slower growth. The best depth for the growth, morphology, and histology of K. alvarezii during the study was observed at a depth of 15 cm. Environmental parameters such as temperature, salinity, water flow rate, water clarity, and pH have a positive influence on the growth of K. alvarezii.

Estimating the effective char depth in structural timber elements exposed to natural fires, considering the heating and cooling phase

This research study investigates the effect of different heating and cooling regimes on the effective cross-section of timber elements exposed to natural fires. An advanced calculation method based on a 1D finite-difference heat transfer model and effective thermo-physical properties is adopted to analyse the heat penetration and the consequent reduction in mechanical properties. In particular, the research focuses on the evolution and penetration speed of the char depth (300 °C isotherm) and zero-strength layer (determined through in-depth temperatures and reduced mechanical properties). Results reveal how the char depth mainly develops during the heating phase, with non-negligible contributions from the cooling phase. In contrast, the zero-strength layer increases throughout the whole fire exposure, particularly during cooling and, possibly, after the end of the cooling phase. In general, the heating phase contributes about 2/3 to the total effective char depth, while the cooling phase about 1/3. The most challenging conditions were found for the fires of the longest durations (heating and overall), corresponding to low ventilation and high fuel load density conditions. The study emphasises the necessity of incorporating the cooling phase in performance-based methodologies for fire-safe timber structures to avoid under-estimating heat penetration effects.

Evidence for large scale compressible turbulence in the ism of CSWA13, a star-Forming Lensed Galaxy at z = 1.87 with outflowing wind

Recently, Keerthi Vasan G. et al. (2024) presented spatially resolved observations of a wind outflow in CSWA13, a gravitationally lensed Star-Forming galaxy at z = 1.87. The gravitational lensing allowed for a substantially improved spatial and kinematic resolution of the wind and of the nebular gas. In this paper we take advantage of the resolved data to test for the existence of turbulence and to study its nature. We obtained the autocorrelation functions of the two velocity fields, and derived the spatial structure functions of the residual nebular and wind velocities along the major axis of the galaxy. The structure functions, of both velocity fields, reveal the existence of an underlying k −2 power spectrum scaling. This scaling suggests the existence of supersonic compressible turbulence. The autocorre- lation functions exhibit correlations over scales comparable to the total extent of the velocity fields. Thus, the turbulence is a large scale one. The turbulent timescale corresponding to the largest scale is about 200 Myr, an order of magnitude larger than the estimated age of the wind and of the young stars. This implies that the turbulence in the ISM formed well before the wind and the young stars. Given the large spatial scale of the turbulence, it is plausible that the source of the turbulence is a large scale one e.g. a merger or tidal event that triggered the formation of molecular clouds, in the cores of which, the young stars formed. A steepening of the structure functions on the smaller scales provides an estimate for the effective depth along the line of sight of the turbulent layer. The latter turns out to be ∼ 2kpc

Numerical and analytical study on the punching shear capacity prediction for eccentrically loaded flat slabs with openings

The punching shear behavior of interior flat slab was examined in this study in the absence of shear reinforcement using numerical and analytical techniques. The effect of sensitive parameters was investigated and their influence was examined and reported including the opening existence and location, loading eccentricity, and slab height. The effect of the reinforcement ratio is neglected in most of the literature models and code provisions with the influence of loading eccentricity being addressed inappropriately. Therefore, this study adopted the nonlinear finite element analysis (NLFEA) method for the numerical part where the flat slab punching shear behavior was studied in detail. Results were compared in their behavior at both cracking and ultimate stages, absorbed energy, elastic and plastic stiffnesses, and general trend lines were provided. The effect of the reinforcement ratio was assessed indirectly with slabs of similar reinforcement area and different slab effective depths (65, 95, 125, and 155) mm where a 25 mm concrete cover was used. In addition, the NLFEA punching shear capacity results were compared with three international codes (American Concrete Institute (ACI318-119), EuroCode (EC2), and Model Code (MC2010)) to highlight their potential predictability and weakness points. It was found that the MC2010 has the most conservative prediction, followed by the EC2 and the ACI318-19 predictions. Therefore, two modification parameters were proposed for the ACI318-19 punching shear capacity calculation with R2 value of 0.98. The modified version of the ACI318-19 was validated using experimental data from the literature proving a high prediction capability.

A SPectroscopic Survey of Biased Halos In the Reionization Era (ASPIRE): JWST Supports Earlier Reionization around [O iii] Emitters

Abstract Understanding when and how reionization happened is crucial for studying the early structure formation and the properties of the first galaxies in the Universe. At z > 5.5, the observed intergalactic medium (IGM) optical depth shows a significant scatter, indicating an inhomogeneous reionization process. However, the nature of the inhomogeneous reionization remains debated. A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE) is a JWST Cycle 1 program that has spectroscopically identified >400 [O iii] emitters in 25 quasar fields at z > 6.5. Combined with deep ground-based optical spectroscopy of ASPIRE quasars, the ASPIRE program provides the current largest sample for IGM-galaxy connection studies during cosmic reionization. We present the first results of IGM effective optical depth measurements around [O iii] emitters using 14 ASPIRE quasar fields. We find the IGM transmission is tightly related to reionization era galaxies to the extent that a significant excess of Lyα transmission exists around [O iii] emitters. We measure the stacked IGM effective optical depth of IGM patches associated with [O iii] emitters and find they reach the same IGM effective optical depth at least d z ∼ 0.1 ahead of those IGM patches where no [O iii] emitters are detected, supporting earlier reionization around [O iii] emitters. Our results indicate an enhancement in IGM Lyα transmission around [O iii] emitters at scales beyond 25 h −1 cMpc, consistent with the predicted topology of reionization from fluctuating UV background models.

Assessment of the quality of full depth reclamation (FDR) using a dynamic cone penetrometer (DCP): a case study

The full-depth reclamation with no stabilization (FDR-NS) is widely used as a pavement rehabilitation technique. It is important to evaluate the on-site characteristics of FDR-NS materials to avoid short-term underperformance. The need for performance-based testing could then be supported by in-situ and non-destructive testing, such as dynamic cone penetrometer (DCP). DCP allows to estimate the bearing capacity of the pavement structure and to verify its homogeneity according to the depth. The objective of this research is to evaluate the applicability of using DCP to assess the quality of FDR-NS. Overall, DCP results showed a good reliability, allows to measure the effective depth of reclamation and to observe a significant reduction (average of 75 %), in terms of DCP values, between before and after the reclamation process. Thus, the potential of using DCP for FDR-NS rehabilitation was confirmed. The results from this research provide a rational basis for establishing specifications.

Scalable Copper Sulfide Formulations for Super-Resolution Optoacoustic Brain Imaging in the Second Near-Infrared Window.

Optoacoustic imaging offers label-free multi-parametric characterization of cerebrovascular morphology and hemodynamics at depths and spatiotemporal resolution unattainable with optical microscopy. Effective imaging depth can greatly be enhanced by employing photons in the second near-infrared (NIR-II) window. However, diminished absorption by hemoglobin along with a lack of suitable contrast agents hinder an efficient application of the technique in this spectral range. Herein, copper sulfide (CuS) micro- and nano-formulations for multi-scale optoacoustic imaging in the NIR-II window are introduced. Dynamic contrast enhancement induced by intravenously administered CuS nanoparticles facilitated visualization of blood perfusion in murine cerebrovascular networks. The individual calcium carbonate microparticles carrying CuS are further shown to generate sufficient responses to enable super-resolution microvascular imaging and blood flow velocity mapping with localization optoacoustic tomography.

Good Formability Despite High Accompanying Element Content of a Modified 20MnB4 Quenched and Tempered Steel

Abstract This article provides a comparative characterization of the mechanical and technological properties of a modified 20MnB4 quenched and tempered steel that are important for further processing. The aim of the modification was to represent the steel as a secondary steel with a significantly increased holding of accompanying elements to be assumed in the future. The aim was to check whether the increased hardening tendency due to increasing levels of accompanying elements can be compensated for by a targeted reduction in the Mn content without negatively affecting through-hardenability and tempering resistance. An industrially available steel was used as a reference condition. The results showed that the reduction of the Mn content contributed to the increase in cold formability, while a strong decrease in effective hardening depth occurred with an insignificant change in tempering behavior.

A Study on the Influence of Hydraulic Compactor Reinforcement on the Force Law of an Independent Foundation Under a Column and Its Safety Standard

Due to the complexity of the actual geotechnical environment, the backfill compaction design theory and calculation method are not reflected in the current specification. Therefore, in order to investigate the effect of the hydraulic compactor on the foundation structure during the treatment of the backfill of an independent foundation under a column, the Menard formula was modified. At the same time, relying on an independent foundation project under a column in Jinan, the dynamic model of compactor tamping backfilling soil was established. The applicability of the calculation formula is verified by simulating the single-point multiple tamping on the backfill directly above the foundation tie beam, and the influence law of two factors, the thickness of the backfill and the tamping energy, on the force of the foundation tie beam is elucidated. The results show that after reaching the optimum number of tamping, the cumulative soil settlement and the effective reinforcement depth of tamping show a stable trend, and their simulation results are in good agreement with the analytical solution, which provides a supplement to the relevant safety standards. At this critical point, the force on the tie beams peaked and showed up and down fluctuations under the subsequent ramming action. The tamping action of the compactor has a significant effect on the structural forces within the effective reinforcement range, and there is a negative correlation between the magnitude of the structural forces and the thickness of the backfill. According to the numerical calculation results to choose the best construction programme, the on-site monitoring shows that under 42 KJ tamping energy and 1.5 m single backfilling thickness, the tie beam reinforcement stress reaches 18.5~55.5% of the specification warning value, which meets the safety standard. The research results of this paper can provide important guidance for the hydraulic tamping treatment of an independent foundation backfill project.

Punching shear performance of reinforced concrete slab-to-steel column connections incorporating ECC and UHPECC

Unlike the conventional reinforced concrete (RC) slab-column connection, the punching shear generated at the RC slab-to-steel column connection may lead to brittle punching shear failure due to the small area around the steel column. Moreover, the unexpected moments arising from eccentric loading can also lead to the failure of the slab in punching shear mode. This paper proposes employing high-performance concrete (HPC) to fill the critical punching shear zone to improve the punching shear resistance of RC slabs to steel column joints. Experiments on eight RC slabs to steel column connections are reported. The test parameters under investigation are the type of HPC used to fill the critical punching shear zone, the distance (S) of the HPC zone measured from the flanges of the steel column and loading condition (concentric and eccentric). The types of HPC include engineered cementitious composite (ECC) and ultra-high performance ECC (UHPECC). The experimental results show that the proposed techniques can significantly improve the cracking load, elastic stiffness, energy absorption capacity, ductility, failure modes, and ultimate load of the slab-to-column connections. The ultimate load of the tested connections is increased by as much as 33 %, and 28 % for the slabs subjected to concentric and eccentric loading, respectively. However, the ultimate load and energy absorption capacity of the slab with UHPECC having a S value of 1d, where d is the effective depth are lower than those of the control slab. Three-dimensional nonlinear finite element models are developed to simulate the performance of tested slab-to-column connections and validated by experimental results. The parametric study shows that the n (=S/d) value greater than 3.5 has insignificant effects on the ultimate punching shear capacity of the slab. It is demonstrated that the proposed formulas faithfully estimate the ultimate punching shear capacity of slab-to-column connections constructed with different HPCs under concentric and eccentric loadings.

Functional properties of expanded austenite generated on AISI 316L by plasma nitrocarburizing using different active screen materials

Abstract This study investigates the functional properties of the expanded austenite layers generated on AISI 316L austenitic stainless steel resulting from active screen plasma nitrocarburizing using different active screen materials, i.e. steel or solid carbon. Treatments were conducted at 460 °C for 5 hours in a nitrogen-hydrogen feed gas, whereas for the treatments using a steel active screen, methane was added as carbon precursor. Additionally, the bias plasma conditions applied at the samples were varied between 0 kW and 1.25 kW. Samples were characterized by complementary microstructural and compositional investigations, surface roughness and hardness measurements, pin-on-disk tribological tests as well as potentiodynamic polarization tests in H2SO4 and NaCl electrolytes. The functional properties of the case are discussed based on the contents of nitrogen and carbon in the expanded austenite and on their effective diffusion depths. The results show that the usage of a carbon screen generally produces surfaces with uniform layer thickness, high hardness, improved wear resistance and a delayed tendency to pitting corrosion independent of the bias condition applied to the samples. When applying both screen materials at non-biased condition, the general corrosion resistance is slightly reduced under the conditions used, however, the layers generated using the carbon screen have a wear rate that is 3 times lower. It can be concluded that the carbon screen represents a robust treatment variant for austenitic stainless steels to produce sufficiently thick and wear-resistant surface layers in a short treatment duration, which still have the potential to maintain the corrosion resistance in different environments.

Depth-prior-based range-gated 3D imaging method: integration of optical property into visual learning

3D Range-gated Imaging (3DRGI) has great potential for long-range detection in adverse weather conditions. Recently, vision-guided 3DRGI has brought new perspectives to this area as it overcomes hardware limitations and greatly increases flexibility. However, existing vision-guided methods do not consider the optical properties of range-gated imaging, which results in low accuracy. This paper proposes a depth-prior-based 3DRGI method to combine the advantages of optical-based and vision-guided methods. In this method, depth-prior is firstly deduced from principles of range-gated imaging and provides effective depth signals. Then, adaptive depth intervals are estimated using statistical methods, and a depth-prior-guided loss function is designed. The integration of the depth-prior-guided loss function within a vision-guided model enables focused attention on pixels with depth estimations that are inconsistent with the depth prior, thereby refining the overall accuracy of the depth map. To prove the feasibility of the proposed method, comparison experiments and ablation studies have been performed. The results show that the root mean square error improved by more than 12% under adverse weather conditions.

Research on Evaluation Method of Natural Gas Hydrate Resources Based on Probability Distribution Model

Natural gas hydrate, as a highly efficient and clean energy source, has garnered significant attention from both developed and energy-deficient nations. However, to achieve industrial application, several technical challenges must be addressed, including resource exploration, spatial positioning, resource assessment, economic production evaluation, and climate change impact assessment. Currently, our exploration and evaluation system for gas hydrate resources remains immature. This study aims to determine the probability distribution of effective thickness, porosity, and saturation of natural gas hydrate resource parameters in the study area and their variations. Utilizing probability statistics theory, we calculated specific values for all gas hydrate resource parameters from open-source data of 14 exploration well locations, determined their probability distributions, and conducted distribution detection to identify specific distributions. Data analysis was performed using linear graphs and bar charts to summarize patterns. Subsequently, by applying the mathematical formula Q = A×Z×∅×S×E, we categorized natural gas hydrate resource parameters, calculated gas hydrate resources at each effective depth, determined the probability distribution of each obtained data point, and ultimately solved for the total natural gas hydrate resources, yielding a final solution of 31875763695.08.

Shear performance of GFRP reinforced UHPC short beams

This paper investigated experimentally the shear performance of ultra-high-performance concrete (UHPC) deep beams reinforced longitudinally with glass fiber reinforced polymer (GFRP) bars without web reinforcements. Ten beams were cast, in which seven were longitudinally reinforced with GFRP bars, while the remaining three were reinforced with steel bars for comparison. All beams had similar lengths and widths of 2000 mm and 150 mm, respectively, while the depths varied. The test parameters included the effective depth (d), shear span-to-depth ratio (a/d), number of longitudinal bars, and longitudinal reinforcement ratio (ρ). All the GFRP reinforced beams had higher shear capacities and lower post cracking stiffness than their steel counterparts. The experimental results show that varying the test parameters have a significant impact on the shear capacity of the beams. For instance, decreasing the a/d ratio for the GFRP reinforced beams from 1.8 to 1.5 and from 1.8 to 1.1 increased the load carrying capacity by 33 % and 95 %, respectively. The experimental results for the shear capacity were compared against the predictions obtained using the strut and tie method as per the ACI-318–19 and CSA-S806-12 codes. The failure load predictions by the ACI and CSA code showed the same trends as those shown in the experimental results. Moreover, both codes were conservative in predicting the shear capacities.

Dense projection fusion for 3D object detection

Fusing information from LiDAR and cameras can effectively enhance the overall perceptivity of autonomous vehicles in various scenarios. Despite the relatively good results achieved by point-wise fusion and Bird’s-Eye-View (BEV) fusion, they still cannot fully leverage the image information and lack of effective depth information. For any fusion methods, the multi-modal features first need to be concatenated along the channel, and then the fused features are extracted using convolutional layers. However, this type of fusion methods is effective, but too coarse which causes that the fused features cannot pay more attention to the regions with important features and suffer from severe noise. To tackle these issues, we propose in this paper a Dense Projection Fusion (DPFusion) approach. It consists of two new modules: dense depth map guided BEV transform (DGBT) module and multi-modal feature adaptive fusion (MFAF) module. The DGBT module first quickly estimates the depth of each pixel and then projects all image features to the BEV space, making full use of the image information. The MFAF module computes the image weights and point cloud weights for each channel in each BEV grid and then adaptively weights and fuses the image BEV features with the point cloud BEV features. It is worth pointing out that the MFAF module makes the fused features pay more attention to background outline and object outline. Our proposed DPFusion demonstrates competitive results in 3D object detection, achieving a mean Average Precision (mAP) of 70.4 and a nuScenes detection score (NDS) of 72.3 on the nuScenes validation set.

Analysis of dynamic response and impact resistance of corrugated plate-reinforced concrete under simulated rockfall

In this study, corrugated plate material is used as the internal mold for the reinforced concrete structure, proposing a combined shelter structure designed to protect against rockfall hazards in mountainous areas. The research focuses on the impact of low-velocity rockfall (below 150 km/h) directly hitting both the reinforced concrete structure and the corrugated plate and reinforced concrete combined shelter structure. The accuracy of the numerical simulation results is validated through comparative analysis with indoor model experiments. Further investigation reveals the impact resistance and failure characteristics of RC (Reinforced Concrete) structures, CPRC(D) (Corrugated plate double-layer reinforced concrete composite structure) structures and CPRC(S)（Corrugated plate single-layer reinforced concrete composite structure）, with the residual resistance index (RRI) introduced for the quantitative analysis of the residual load-bearing capacity of the protective structures post-impact. The results indicate that the shape of impact craters and the maximum impact force obtained through numerical simulations closely match the experimental findings, demonstrating the validity of the simulation parameters. Under the same impact energy, the maximum peak stress at various points in the CPRC structure is reduced by more than 50 % compared to the RC structure. Damage to the RC structure under rockfall impact is primarily characterized by central penetration failure and extensive development of diagonal cracks. In contrast, the CPRC structure effectively suppresses penetration, dent deformation, and crack propagation, significantly reducing the volume of concrete damage and the proportion of rebar damage, with the residual resistance index consistently remaining above 0.27.The corrugated plate and reinforced concrete combined structure outperforms the reinforced concrete structure in several impact resistance factors, including maximum impact force, effective stress extremes, structural damage, and penetration depth. Additionally, after reinforcement with corrugated plates, the CPRC structure maintains a high level of impact resistance in most scenarios, even when the lower layer of rebar is eliminated, providing a theoretical basis and preliminary feasibility proof for the lightweight modification of the structure.

Age-Related Response to Remimazolam among Older Patients Undergoing Orthopedic Surgery: A Single-Center Prospective Observational Study

Background and Objectives: Remimazolam, an ultra-short-acting benzodiazepine, is increasingly used in procedural sedation and general anesthesia. It is characterized by rapid onset of action, inactive metabolites, no delay in recovery, and few adverse events. Its hemodynamic and respiratory stability are comparable to other anesthetics, and it is safe in high-risk and geriatric patients. Materials and Methods: This prospective, observational study enrolled 110 geriatric patients (aged 65 to 85 years) scheduled for primary total knee arthroplasty (TKA). The patients were divided into the old (65 to <75 years; n = 52) and the elderly (75 to 85 years; n = 47) geriatric groups. All surgical and anesthetic methods were applied in the same manner, and TKA was performed by one surgeon. Remimazolam was infused at 6 mg/kg/h for 3 min and then at 1 mg/kg/h until the end of surgery The primary study endpoint was the requirement for flumazenil; secondary endpoints were the times to reach a bispectral index (BIS) < 60 and >80, as well as the rate of apnea occurrence. Results: Flumazenil administration was similar in both groups. There were no differences in the time to reach BIS < 60 or the rate of apnea occurrence. Recovery characteristics, including the time to reach BIS > 80 and the achievement of full consciousness, were also comparable between the groups. Conclusions: Remimazolam is well-tolerated in geriatric patients undergoing orthopedic surgery, with minimal age-related differences in response. These results suggest that remimazolam is an appropriate anesthetic for geriatric patients, even with similar dosing strategies. It provides effective anesthetic depth with no significant increases in adverse outcomes during orthopedic surgery.

A new census of dust and polycyclic aromatic hydrocarbons at z = 0.7–2 with JWST MIRI

Aims. This paper utilises the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) to extend the observational studies of dust and polycyclic aromatic hydrocarbon (PAH) emission to a new mass and star formation rate (SFR) parameter space beyond our local Universe. The combination of fully sampled spectral energy distributions (SEDs) with multiple mid-infrared (mid-IR) bands and the unprecedented sensitivity of MIRI allows us to investigate dust obscuration and PAH behaviour from z = 0.7 up to z = 2 in typical main-sequence galaxies. Our focus is on constraining the evolution of PAH strength and the dust-obscured luminosity fraction before and during cosmic noon, the epoch of peak star formation activity in the Universe. Methods. In this study, we utilise MIRI multi-band imaging data from the SMILES survey (5 to 25 μm), complemented with NIRCam photometry from the JADES survey (1 to 5 μm), available HST photometry (0.4 to 0.9 μm), and spectroscopic redshifts from the FRESCO and JADES surveys in GOODS-S for 443 star-forming (without dominant active galactic nucleus (AGN)) galaxies at z = 0.7 − 2.0. This redshift range was chosen to ensure that the MIRI data cover mid-IR dust emission. Our methodology involved employing ultraviolet (UV) to IR energy balance SED fitting to robustly constrain the fraction of dust mass in PAHs and dust-obscured luminosity. Additionally, we inferred dust sizes from MIRI 15 μm imaging data, enhancing our understanding of the physical characteristics of dust within these galaxies. Results. We find a strong correlation between the fraction of dust in PAHs (PAH fraction, qPAH) with stellar mass. Moreover, the sub-sample with robust qPAH measurements (N = 216) shows a similar behaviour between qPAH and gas-phase metallicity to that at z ∼ 0, suggesting a universal relation: qPAH is constant (∼3.4%) above a metallicity of Z ∼ 0.5 Z⊙ and decreases to < 1% at metallicities ≲0.3 Z⊙. This indicates that metallicity is a good indicator of the interstellar medium properties that affect the balance between the formation and destruction of PAHs. The lack of a redshift evolution from z ∼ 0 − 2 also implies that above Z ∼ 0.5 Z⊙ the PAH emission effectively traces obscured luminosity and the previous locally calibrated PAH-SFR calibrations remain applicable in this metallicity regime. We observe a strong correlation between the obscured UV luminosity fraction (ratio of obscured to total luminosity) and stellar mass. Above the stellar mass of M* > 5 × 109 M⊙, on average, more than half of the emitted luminosity is obscured, while there exists a non-negligible population of lower-mass galaxies with > 50% obscured fractions. At a fixed mass, the obscured fraction correlates with SFR surface density. This is a result of higher dust covering fractions in galaxies with more compact star-forming regions. Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UV continuum slope (β) tend to have higher ΣSFR and shallower attenuation curves, owing to their higher effective dust optical depths and more compact star-forming regions.

Do Subsampling Strategies Reduce the Confounding Effect of Errors in Bispectral Retrievals on Estimates of Aerosol Cloud Interactions?

AbstractBi‐spectral retrievals of droplet effective radius and cloud optical depth are widely utilized to estimate aerosol cloud interactions (ACI) in warm clouds in the marine boundary layer. Here, we assess the effect of retrieval errors due to the neglect of 3D radiative transfer during the retrieval process on this analysis of ACI. We use an ensemble of stochastically‐modeled cloud fields and 3D radiative transfer simulations to study the retrieval errors at a solar zenith angle of 30°. Simulated retrieval biases in droplet number concentration (Nd) for all three MODIS channels vary systematically from +35% to −80% as cloud heterogeneity increases. Pixel‐level errors can be much larger. Commonly utilized subsampling strategies do not reduce the systematic variation in retrieval error. Negative error correlations between optical depth and droplet effective radius produce spuriously negative slopes between the logarithm of liquid water path and Nd (−1.0 to −0.3). Pixels at the center of (8 km)2 patches that are not overcast have a relative bias in Nd of −50%. The relative frequency of these biased pixels varies linearly with the clear fraction in MODIS data and form the basis for a simple parameterization of Nd bias that varies with cloud fraction (CF). Using this parameterization, synthetic data experiments indicate that estimates of the first indirect effect in the tropical ocean can be overestimated by up to 30%, and the effect of aerosol on CF is overestimated by 50%, due to neglecting the correlation between retrieval errors and cloud microphysics.