Accelerating Atmospheric Gravity Wave Simulations using Machine Learning: Kelvin-Helmholtz Instability and Mountain Wave Sources Driving Gravity Wave Breaking and Secondary Gravity Wave Generation

Gravity waves (GWs) and their associated multi-scale dynamics are known to play fundamental roles in energy and momentum transport and deposition processes throughout the atmosphere. We describe an initial, two-dimensional (2-D), machine learning model – the Compressible Atmosphere Model Network (CAMNet) - intended as a first step toward a more general, three-dimensional, highly-efficient, model for applications to nonlinear GW dynamics description. CAMNet employs a physics-informed neural operator to dramatically accelerate GW and secondary GW (SGW) simulations applied to two GW sources to date. CAMNet is trained on high-resolution simulations by the state-of-the-art model Complex Geometry Compressible Atmosphere Model (CGCAM). Two initial applications to a Kelvin-Helmholtz instability source and mountain wave generation, propagation, breaking, and SGW generation in two wind environments are described here. Results show that CAMNet can capture the key 2-D dynamics modeled by CGCAM with high precision. Spectral characteristics of primary and SGWs estimated by CAMNet agree well with those from CGCAM. Our results show that CAMNet can achieve a several order-of-magnitude acceleration relative to CGCAM without sacrificing accuracy and suggests a potential for machine learning to enable efficient and accurate descriptions of primary and secondary GWs in global atmospheric models

Gravity Waves Emitted from Kelvin-Helmholtz Instabilities

Fritts, Wang, Lund, and Thorpe (2022, https://doi.org/10.1017/jfm.2021.1085) and Fritts, Wang, Thorpe, and Lund (2022, https://doi.org/10.1017/jfm.2021.1086) described a 3-dimensional direct numerical simulation of interacting Kelvin-Helmholtz instability (KHI) billows and resulting tube and knot (T&K) dynamics that arise at a stratified shear layer defined by an idealized, large-amplitude inertia-gravity wave. Using similar initial conditions, we performed a high-resolution compressible simulation to explore the emission of GWs by these dynamics. The simulation confirms that such shear can induce strong KHI with large horizontal scales and billow depths that readily emit GWs having high frequencies, small horizontal wavelengths, and large vertical group velocities. The density-weighted amplitudes of GWs reveal “fishbone” structures in vertical cross sections above and below the KHI source. Our results reveal that KHI, and their associated T&K dynamics, may be an important additional source of high-frequency, small-scale GWs at higher altitudes

Analysis of Energy Transfer among Background Flow, Gravity Waves and Turbulence in the mesopause region in the process of Gravity Wave Breaking from a High-resolution Atmospheric Model

We conducted an analysis of the process of GW breaking from an energy perspective using the output from a high-resolution compressible atmospheric model. The investigation focused on the energy conversion and transfer that occur during the GW breaking. The total change in kinetic energy and the amount of energy converted to internal energy and potential energy within a selected region were calculated. Prior to GW breaking, part of the potential energy is converted into kinetic energy, most of which is transported out of the chosen region. After the GW breaks and turbulence develops, part of the potential energy is converted into kinetic energy, most of which is converted into internal energy. The calculations for the transfer of kinetic energy among GWs, turbulence, and the BG in a selected region, as well as the contributions from various interactions (BG-GW, BG-turbulence, and GW-turbulence), are performed. At the point where the GW breaks, turbulence is generated. As the GW breaking process proceeds, the GWs lose energy to the background. At the start of the GW breaking, turbulence receives energy through interactions between GWs and turbulence, and between the BG and turbulence. Once the turbulence has accumulated enough energy, it begins to absorb energy from the background while losing energy to the GWs. The probabilities of instability are calculated during various stages of the GW-breaking process. The simulation suggests that the propagation of GWs results in instabilities, which are responsible for the GW breaking. As turbulence grows, it reduces convective instability

Assessment of toxicity reduction in ZnS substituted CdS:P3HT bulk heterojunction solar cells fabricated using a single-source precursor deposition

Utilisation of cadmium sulphide (CdS) for the preparation of hybrid bulk heterojunction (BHJ) solar cells is limited due to its high human, soil and marine toxicity. This work aims to reduce the toxicity of the cadmium based hybrid bulk heterojunctions, by varying the composition of metal sulphide nanoparticles between CdS and zinc sulphide (ZnS). Furthermore, these devices were created using a single-source precursor, which limits potential barriers for scaling up this process to industrial scale. It was found that the chemical composition of fabricated devices varied as expected; however, comparable morphologies were noted by SEM analyses. Toxicity of fabricated photovoltaic devices was estimated according to the life cycle assessment methodology, using the SimaPro software. Although negligible changes between the band gaps of prepared devices were calculated by decreasing the Cd load to 50 wt%, over 50 % reduction to human toxicity could be achieved. As a photovoltaic device, the highest power conversion efficiency (0.018 %) was observed for the device containing 75 wt% Cd and 25 wt% Zn, which also showed significant reductions for human and environmental toxicity (25 % and 19 % reduction, respectively) in comparison to the device containing only CdS, while increasing the power conversion efficiency by roughly 30 %. It was also noted that although the ZnS only device had the lowest efficiency (0.002 %, a decrease of roughly 98 %), however, this allowed for a 99 % reduction in human toxicity and a 73 % reduction in terrestrial ecotoxicity

Direct observation of nucleation in the bulk of an opaque sample

Remarkably little is known about the physical phenomena leading to nucleation of new perfect crystals within deformed metals during annealing, in particular how and where volumes with nearly perfect lattices evolve from structures filled with dislocations, and how local variations at the micrometer length scale affect this nucleation process. We present here the first experimental measurements that relate directly nucleation of recrystallization to the local deformation microstructure in the bulk of a sample of cold rolled aluminum, further deformed locally by a hardness indentation. White beam differential aperture X-ray microscopy is used for the measurements, allowing us to map a selected gauge volume in the bulk of the sample in the deformed state, then anneal the sample and map the exact same gauge volume in the annealed state. It is found that nuclei develop at sites of high stored energy and they have crystallographic orientations from those present in the deformed state. Accordingly we suggest that for each nucleus the embryonic volume arises from a structural element contained within the voxels identified with the same orientation. Possible nucleation mechanisms are discussed and the growth potentials of the nuclei are also analyzed and discussed

Synergistic effects of ginsenoside Rg3 and cyclophosphamine on tumor growth and angiogenesis in lung cancer

To evaluate the effectiveness of ginsenoside Rg3 alone or in combination with cyclophosphamide (CPA) on tumor growth and angiogenesis in human lung cancer, 54 female athymic mice were transplanted with lung cancer cells (A549) which then were randomly divided into 4 groups: Ginsenoside Rg3 group, CPA group, ginsenoside Rg3 plus CPA group and control group. Ginsenoside Rg3 of 3.0 mg/kg (once/day for 10 days) and CPA of 20.0 mg/kg (once/day for 10 days) were intraperitoneally given to mice for consecutive 10 days. Seven mice selected from each group were sacrificed 18 days later. The survival time of the remaining 7 mice in each group was recorded. The life elongation rate, proliferating cell nuclear antigen labeling index (PCNALI), expression of vascular endothelial cell growth factor (VEGF) and microvessel density (MVD) in the tumor tissues were evaluated. The quality of life of mice with administration of ginsenoside Rg3 alone or ginsenoside Rg3 plus CPA were better with longer survival time, when compared with other groups. The PCNALI, MVD and VEGF expression in mice of the treated groups were significantly lowered when compared with that of the control group. Additionally, the MVD of mice in groups with treatment of ginsenoside Rg3 alone or ginsenoside Rg3 plus CPA were lower than that in the CPA group. Tumor growth and angiogenesis in lung cancer were profoundly inhibited by ginsenoside Rg3 alone or in combination with CPA. The synergistic anticancer effects of ginsenoside Rg3 and CPA improved the survival time in lung cancer.Key words: Ginseng, cyclophosphamide, angiogenesis, lung cancer

Modeling Studies of Gravity Wave Dynamics in Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, and Induced Flow Responses

A compressible numerical model is applied for three-dimensional (3-D) gravity wave (GW) packets undergoing momentum deposition, self-acceleration (SA), breaking, and secondary GW (SGW) generation in the presence of highly-structured environments enabling thermal and/or Doppler ducts, such as a mesospheric inversion layer (MIL), tidal wind (TW), or combination of MIL and TW. Simulations reveal that ducts can strongly modulate GW dynamics. Responses modeled here include reflection, trapping, suppressed transmission, strong local instabilities, reduced SGW generations, higher altitude SGW responses, and induced large-scale flows. Instabilities that arise in ducts experience strong dissipation after they emerge, while trapped smaller-amplitude and smaller-scale GWs can survive in ducts to much later times. Additionally, GW breaking and its associated dynamics enhance the local wind along the GW propagation direction in the ducts, and yield layering in the wind field. However, these dynamics do not yield significant heat transport in the ducts. The failure of GW breaking to induce stratified layers in the temperature field suggests that such heat transport might not be as strong as previously assumed or inferred from observations and theoretical assessments. The present numerical simulations confirm previous finding that MIL generation may not be caused by the breaking of a transient high-frequency GW packet alone

Use of Practice-Based Research Network Data to Measure Neighborhood Smoking Prevalence

Introduction: Practice-Based Research Networks (PBRNs) and health systems may provide timely, reliable data to guide the development and distribution of public health resources to promote healthy behaviors, such as quitting smoking. The objective of this study was to determine if PBRN data could be used to make neighborhood-level estimates of smoking prevalence. Methods: We estimated the smoking prevalence in 32 greater Boston neighborhoods (population = 877,943 adults) by using the electronic health record data of adults who in 2009 visited one of 26 Partners Primary Care PBRN practices (n = 77,529). We compared PBRN-derived estimates to population-based estimates derived from 1999–2009 Behavioral Risk Factor Surveillance System (BRFSS) data (n = 20,475). Results: The PBRN estimates of neighborhood smoking status ranged from 5% to 22% and averaged 11%. The 2009 neighborhood-level smoking prevalence estimates derived from the BRFSS ranged from 5% to 26% and averaged 13%. The difference in smoking prevalence between the PBRN and the BRFSS averaged −2 percentage points (standard deviation, 3 percentage points). Conclusion: Health behavior data collected during routine clinical care by PBRNs and health systems could supplement or be an alternative to using traditional sources of public health data

Knowledge Driven Phenotyping

Extracting patient phenotypes from routinely collected health data (such as Electronic Health Records) requires translating clinically-sound phenotype definitions into queries/computations executable on the underlying data sources by clinical researchers. This requires significant knowledge and skills to deal with heterogeneous and often imperfect data. Translations are time-consuming, error-prone and, most importantly, hard to share and reproduce across different settings. This paper proposes a knowledge driven framework that (1) decouples the specification of phenotype semantics from underlying data sources; (2) can automatically populate and conduct phenotype computations on heterogeneous data spaces. We report preliminary results of deploying this framework on five Scottish health datasets