Search Constraints
Filtering by:
Language
English
Remove constraint Language: English
Discipline
Science
Remove constraint Discipline: Science
« Previous |
1 - 10 of 931
|
Next »
Number of results to display per page
View results as:
Search Results
-
- Creator:
- Zetterberg, Daniel S., Huang, Xianglei, Hörner, Johannes, Voigt, Aiko, and Chen, Xiuhong
- Description:
- The data and code stored in this repository present the results of the paper "Instantaneous radiative effect of surface long wave spectral emissivity in a Snowball Earth simulation." In this paper, we calculate the instantaneous radiative effects of surface spectral emissivity for a Snowball Earth simulation, and find that including surface spectral emissivity has a moderate effect on the radiation budget. For clear-sky conditions, using ice or snow spectral emissivity can decrease outgoing long wave radiation by 2.9 or 1.0 W/m^2, respectively, globally averaged. This large effect could impact the simulated climate state of a Snowball Earth and potentially strengthen the Jormungand mechanism. Additionally, the large difference between ice and snow highlights the importance of precipitation processes in Snowball modeling. , This repository contains the results of the calculations and the data and code needed to recreate the manuscript figures. It contains atmospheric conditions from the simulations run by JH and AV that were processed by DSZ. It also contains emissivity datasets that were compiled by Huang et al. 2016 ("A global data set of surface spectral emissivity for GCM and NWP use"). MODTRAN calculations of the outgoing longwave radiation were processed by DSZ, XLH, and XC. The results of the study are contained in netcdf files. The README file offers a description, and the Jupyter notebook demonstrates how to access, use, and plot the calculations. , and ***Changes on 10 June, 2025*** New data files contain the outgoing longwave radiation from MODTRAN calculations, but with multiple scattering enabled in MODTRAN. The result is that downward atmospheric radiation can reflect off the surface back to the top of the atmosphere. The result is that the effect of surface emissivity is slightly decreased, though the conclusions and discussion remain unchanged. Additionally, Xiuhong Chen was added as an author, as her expertise in MODTRAN aided in resolving this issue. Data for a plot of a sample emission spectrum was also added, as this was used in the revised manuscript. Key points were updated to match those in the related article.
- Keyword:
- Spectral surface emissivity, Snowball Earth, paleoclimate modeling
- Citation to related publication:
- Zetterberg, D.S., Huang, X.L., Hörner, J., & Voigt, A. Instantaneous radiative effect of surface long wave spectral emissivity in a Snowball Earth simulation. Submitted to Journal of Geophysical Research: Atmospheres, February 2025
- Discipline:
- Science
-
- Creator:
- Colón-Rodríguez, Stephanie, Liemohn, Michael, Raines, Jim, and Lepri, Susan T.
- Description:
- During its trajectory, Wind spent a significant amount of time in the magnetotail, where its SupraThermal Ion Composition Spectrometer (STICS) measured the mass and mass per charge of protons, alpha particles, and heavy ions with an energy/charge ratio up to 226 keV/e. Although STICS originally aimed to measure the abundance of these ion species in the solar wind, its measurements within the magnetosphere from 1995 to 2002 help us identify preferential entry between the different solar wind ion species. This study statistically analyzes how the ratio between solar wind heavy ions and alpha particles (Heavies Solar Wind / He2+) varies for different upstream conditions and locations within the magnetosphere: northward vs. southward Interplanetary Magnetic Field (IMF), low vs. high solar wind density (Nsw), low vs. high solar wind dynamic pressure (PDyn), slow vs. fast solar wind (Vsw), and dawn vs. dusk. Our results indicate that the HeaviesSolar Wind enter the magnetosphere more efficiently than He2+ during northward IMF and that the Heavies Solar Wind / He2+ ratios decrease during high PDyn. In addition, the Heavies Solar Wind / He2+ ratios exhibit a dawn-dusk asymmetry, highly skewed towards the dawn side for all upstream cases likely due to charge-exchange processes.
- Keyword:
- Magnetosphere, Wind STICS, Solar wind heavy ions, Alpha particles, and dawn-dusk asymmetry
- Citation to related publication:
- Colón-Rodríguez, S., Liemohn, M. W., Raines, J. M, & Lepri, S.T. (2024). Solar wind heavy ions and alpha particles within Earth’s magnetosphere and their variability with upstream conditions. Journal of Geophysical Research Space Physics. In preparation.
- Discipline:
- Science
-
Publicly available repository for "Polariton Chern Bands in 2D Photonic Crystals beyond Dirac Cones"
- Creator:
- Xie, Xin, Sun, Kai, and Deng, Hui
- Description:
- This study explores new platforms for realizing polariton Chern bands in 2D photonic crystals (PhCs) by moving beyond the traditional Dirac cone framework. It focuses on band structures with symmetry-protected bound states in the continuum and Γ-point degeneracies, enabling larger topological gaps, higher Chern numbers, and more uniform Berry curvature—features crucial for experiments and device applications. Eigenvalue and Berry curvature calculations were performed using MATLAB and Mathematica, while Lumerical FDTD was used to simulate photonic and polaritonic band structures in realistic TMD-PhC systems, as well as edge-state dispersion. Reproducing the data requires access to these software tools.
- Keyword:
- Topological photonics, Topological polariton, Topological insulator, and Chern insulator
- Citation to related publication:
- Xie, Xin, Sun, Kai, Deng, Hui. Polariton Chern Bands in 2D Photonic Crystals beyond Dirac Cones. Phys. Rev. X, 15(2), 021061 (2025). https://doi.org/10.1103/PhysRevX.15.021061
- Discipline:
- Science
-
- Creator:
- Gergely Koban, Judit Szente, Bart van der Holst, Gabor Toth, and Enrico Landi
- Description:
- This study aims to assess the performance of coronal models across multiple solar cycles and to analyze long-term variations in solar coronal structures observed in multiple EUV channels. To achieve this, we developed a comprehensive database of solar corona (data cubes) and inner heliosphere simulation outputs using the Alfvén Wave Solar atmosphere Model (AWSoM) within the Space Weather Modeling Framework (SWMF) for Solar Cycles 24 and 25 (SC24 and SC25). This database enables us to investigate the temporal evolution of solar wind source regions—Coronal Holes (CH) and Active Regions (AR). Model accuracy was assessed by comparing synthetic images with concurrent AIA observations in six EUV channels (94, 131, 171, 193, 211, and 335 Å). Additionally, we evaluated the reliability of AWSoM’s solar wind plasma outputs at 1 AU by comparing them with OMNI data for each Carrington Rotation (CR).
- Keyword:
- Solar Corona, SWMF, Solar Physics, Solar Cycle, and MHD Modelling
- Citation to related publication:
- Koban et al. (2025). Validation of Long-Term Solar Coronal Modeling Using FORWARD (Under review).
- Discipline:
- Science
-
- Creator:
- Haynes, Laura M, Holding, Matthew L, Woodard, Jaie, Siemieniak, David, and Ginsburg, David
- Description:
- A phage displayed amino acid site-saturated variant library of plasminogen activator inhibitor (PAI-1) was screened for thermodynamic functional stability. The data are interpreted in the context of protein evolution and computational variant effect/protein stability predictors. This data set contains FASTQ files of the PAI-1 sequence variants that affect its thermodynamic stability, as well as scripts needed to analyze these files.
- Keyword:
- serpins, deep mutational scanning, thermodynamics, metastable proteins, and purifying selection
- Citation to related publication:
- Haynes LM, Holding ML,Woodard J, Siemieniak D, Ginsburg D. Thermodynamics and selection of the plasminogen activator inhibitor-1 latency transition. bioRxiv [Preprint]. 2025.06.03.655624; doi: https://doi.org/10.1101/2025.06.03.655624
- Discipline:
- Science
-
- Creator:
- Moore, Talia Y., Danforth, Shannon M., Larson, Joanna G., and Davis Rabosky, Alison R.
- Description:
- Warning signals in chemically defended organisms are critical components of predator-prey interactions, often requiring multiple coordinated display components for a signal to be effective. When threatened by a predator, venomous coral snakes (genus Micrurus) display a vigorous, non-locomotory thrashing behaviour that has been only qualitatively described. Given the high-contrast and often colourful banding patterns of these snakes, this thrashing display is hypothesized to be a key component of a complex aposematic signal under strong stabilizing selection across species in a mimicry system. By experimentally testing snake response across simulated predator cues, we analysed variation in the presence and expression of a thrashing display across five species of South American coral snakes. Although the major features of the thrash display were conserved across species, we found significant variation in the propensity to perform a display at all, the duration of thrashing, and the curvature of snake bodies that was mediated by predator cue type, snake body size, and species identity. We also found an interaction between curve magnitude and body location that clearly shows which parts of the display vary most across individuals and species. Our results suggest that contrary to the assumption in the literature that all species and individuals perform the same display, a high degree of variation persists in thrashing behaviour exhibited by Micrurus coral snakes despite presumably strong selection to converge on a common signal. This quantitative behavioural characterization presents a new framework for analysing the non-locomotory motions displayed by snakes in a broader ecological context, especially for signalling systems with complex interaction across multiple modalities.
- Keyword:
- aposematism, biomechanics, coral snake mimicry, curvature, Elapidae, non-locomotory motion, Peruvian Amazon, and snake behaviour
- Citation to related publication:
- Moore, T. Y., Danforth, S. M., Larson, J. G., & Davis Rabosky, A. R. (2020). A Quantitative Analysis of Micrurus Coral Snakes Reveals Unexpected Variation in Stereotyped Anti-Predator Displays Within a Mimicry System. Integrative Organismal Biology, 2(1). https://doi.org/10.1093/iob/obaa006
- Discipline:
- Science
-
- Creator:
- Ruas, Terry, Ferreira, Charles H. P., Grosky, William, França, Fabrício O., and Medeiros, Débora M. R,
- Description:
- The relationship between words in a sentence often tell us more about the underlying semantic content of a document than its actual words, individually. Recent publications in the natural language processing arena, more specifically using word embeddings, try to incorporate semantic aspects into their word vector representation by considering the context of words and how they are distributed in a document collection. In this work, we propose two novel algorithms, called Flexible Lexical Chain II and Fixed Lexical Chain II that combine the semantic relations derived from lexical chains, prior knowledge from lexical databases, and the robustness of the distributional hypothesis in word embeddings into a single decoupled system. In short, our approach has three main contributions: (i) unsupervised techniques that fully integrate word embeddings and lexical chains; (ii) a more solid semantic representation that considers the latent relation between words in a document; and (iii) lightweight word embeddings models that can be extended to any natural language task. Knowledge-based systems that use natural language text can benefit from our approach to mitigate ambiguous semantic representations provided by traditional statistical approaches. The proposed techniques are tested against seven word embeddings algorithms using five different machine learning classifiers over six scenarios in the document classification task. Our results show that the integration between lexical chains and word embeddings representations sustain state-of-the-art results, even against more complex systems. Github: https://github.com/truas/LexicalChain_Builder
- Keyword:
- document classification, lexical chains, word embeddings, synset embeddings, chain2vec, and natural language processing
- Citation to related publication:
- Terry Ruas, Charles Henrique Porto Ferreira, William Grosky, Fabrício Olivetti de França, Débora Maria Rossi de Medeiros, "Enhanced word embeddings using multi-semantic representation through lexical chains", Information Sciences, 2020, https://doi.org/10.1016/j.ins.2020.04.048
- Discipline:
- Other, Science, and Engineering
-
- Creator:
- Howard, Cecilia M. and Sheldon, Nathan D.
- Description:
- This study uses a compilation of microbialite occurrences in the Archean and Paleoproterozoic from the literature to investigate how depositional environment changed across environmental shifts such as the Great Oxidation Event and the Huronian Glaciations. Key Points: - We compiled microbialite occurrences from the Archean and Paleoproterozoic with broad depositional environment information, which has not previously been incorporated in larger compilations of occurrences. - Tidal and other terrestrially-influenced settings comprise the majority of the early microbialite record, even across major environmental shifts and Abstract: Changes in microbialite abundance during the Archean and Paleoproterozoic have been attributed to a variety of environmental and biological factors. Past work looking at large-scale patterns of microbialite abundance generally assumes shallow marine deposition rather than incorporating specific settings, however, there is significant variance in conditions that might impact microbialite formation and preservation between marine, tidal, and terrestrial environments. We compiled microbialite occurrences from the Archean and Paleoproterozoic with integrated depositional environment information in order to assess how microbialite development and preservation changed across different settings. Microbially induced sedimentary structures formed a significant part of the record, but their identification primarily in conjunction with stromatolites rather than independently suggests that they may be undercounted. Broad trends in abundance were similar to previous compilations, but critically, we found that the majority of microbialites from this period formed in tidal environments. The proportion of terrestrially-influenced (including tidal) microbialites increased during periods of craton development in the Neoarchean and mid-Paleoproterozoic, with increases in marine microbialite abundance trailing. Tidal microbialite abundance also recovered more quickly than marine abundance following the Great Oxidation Event and Huronian Glaciations.
- Keyword:
- Microbialite, Stromatolite, Archean, Paleoproterozoic, Geosciences, and Tidal
- Citation to related publication:
- Howard, C.M. and Sheldon, N.D. (in prep). Chapter 2 Microbialite Niches across the Archean and Paleoproterozoic.
- Discipline:
- Science
-
- Creator:
- Howard, Cecilia M., Sheldon, Nathan D., Loveall, Zachary, Keating, Katarina A., Hong, Jungpyo, Smith, Selena Y., and Passey, Benjamin H.
- Description:
- This study uses an array of stratigraphic, morphological, and geochemical tools to investigate lateral and temporal variability in environmental records preserved by microbialites during a global hothouse environment. It also inverts tools for reconstructing environmental conditions to elucidate ancient microbial processes. Key Points: - The Green River Basin, WY, USA preserves lacustrine microbialites deposited during the Early Eocene Climatic Optimum, a period of high CO2 and temperatures - Morphological and geochemical analyses of these microbialites preserve variable local, regional, and global environmental conditions - Measurements of environmental conditions can be inverted to understand ancient microbial processes, which could be used to inform modeling of microbial influences on carbon cycling and Abstract: The Green River Basin, WY, USA, contains extensive lacustrine microbialite beds that formed during the hothouse Early Eocene Climatic Optimum (53–49 Ma). The records of biological, chemical, and physical processes preserved in these microbialites can inform our understanding of terrestrial conditions in this warm climate, but separating the competing signals of local, regional and global changes is difficult. Studies focusing on individual localities may miss spatial drivers of differences in microbialites. In this study, we used stratigraphic, morphological, and geochemical techniques to study microbialites deposited in the Green River Basin across three million years spanning the peak of the EECO, including samples from two beds covering 13–25 km of lateral extent. These samples cover a broad set of lake conditions as well as local differences such as spring deposits. We found that these microbialites preserved a mixture of conditions such as global hothouse temperatures, regional shifts in lake level, and local variability from sediment and water sources. Morphological and elemental variability were driven primarily by local and regional conditions such as stream, spring, and clastic inputs and water depth. Isotopic data preserved these local and regional changes as well as evidence of global hothouse conditions. Comparison of past [CO2] estimates to reconstructions using organic and inorganic carbon isotopes with clumped isotope-derived temperatures provides evidence for low to moderate microbial growth rates in these microbialite building communities, demonstrating that environmental tools can be inverted to better understand ancient microbial processes. A diverse toolkit was necessary to isolate the individual controls on microbialite records, and comparing across both space and time enabled us to identify local drivers that lead to significant differences from the expected regional signal.
- Keyword:
- Geosciences, Paleoclimate, Microbialite, Stromatolite, Eocene, Paleolake, and Green River Basin
- Citation to related publication:
- Howard, C.M., et al. (in prep). Disentangling Morphological and Chemical Records of Climate, Hydrology, and Diagenesis in Microbialites from the Eocene Green River Basin, WY, USA.
- Discipline:
- Science
-
- Creator:
- Howard, Cecilia M., Velazquez, Diana, Rico, Kathryn I., and Sheldon, Nathan D.
- Description:
- This study combines a field survey time series with analysis of remotely and locally sensed environmental and climate data. Field survey data consists of sediment chemistry from hand-push cores, and includes %Corg, %N, δ13Corg, Corg:N, collection month and year, and depth in sediment. Climate and environmental data for the region around Middle Island Sinkhole was pulled from publicly available NOAA databases (ERDDAP, National Data Buoy Center, NWS) for as much of the same time period as the sediment data as was available. These data included general weather information from the NDBC and NWS (air temperature, wind speed, wind direction, gust speed, monthly precipitation totals), as well as satellite-derived environmental data from a 0.25° area centered on MIS (ice cover, lake surface temperature, CDOM, DOC, Chlorophyll, suspended minerals). Data were processed to monthly and annual averages as described below in order to compare to sinkhole sediment chemistry. Abstract: Records of recent past climate provide an essential window into understanding how changing climate influences environments and ecosystems such as lakes. Sediment carbon and nitrogen chemistry can offer insight into productivity and biochemistry, and anoxic sediments can often preserve short-term changes in these signals. We found that seasonal and annual changes in local ice season, chlorophyll, and precipitation influenced the amount and isotopic composition of carbon reaching the sediments of Middle Island Sinkhole, an anoxic sinkhole in Lake Huron. Carbon and nitrogen signals reflected the year or season of sample collection in sediments as deep as 12 cm. Our findings demonstrate that declining ice cover in this part of the Great Lakes is leading to increased export of organic carbon into sediments, but that in situ sediment processes may make teasing out short-term changes from sediment cores difficult even in an anoxic setting.
- Keyword:
- Carbon burial, Great Lakes, Ice cover, Sediment carbon, Sediment nitrogen, Anoxia, and Geosciences
- Citation to related publication:
- Howard, C.M., et al. (in prep). Climate-driven changes in sediment carbon and nitrogen of an anoxic Lake Huron sinkhole.
- Discipline:
- Science