93 research outputs found
DELAUNAY-LAGUERRE GEOMETRY FOR MACROMOLECULAR MODELING AND IMPLICIT SOLVATION
We develop and implement geometric methods to study three-dimensional structures of proteins, the knowledge of which is critical to the understanding of the molecules and their interactions. Delaunay and Laguerre methods, which concern sets of overlapping spheres and their interrelationships, are well suited to the study of molecules. We discuss and implement algorithms for the calculation of molecular volume, atomic solvent accessible surface areas, their gradients and discontinuities. This is used for a detailed analysis of parameters obtained by the implicit solvation method, Semi-Explicit Assembly (SEA). We introduce the concept of Laguerre-Intersection cells which consist of the intersection of the Laguerre tessellation and space-filling diagram. This method eliminates the need for explicit water molecules to cap infinite Laguerre cells of certain solvent accessible solute atoms. We discuss and implement a quick weighted Delaunay tetrahedrization algorithm which is tailored specifically to the aforementioned algorithms. Finally, we use concepts from continuum mechanics to study the motion of the HIV protease dimer
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Probabilistic Assessment of Coastal Bridge Vulnerability to Wave Loading During Hurricanes
Bridges located in coastal areas may be subjected to extreme wave and surge loading during coastal storm events, potentially leading to damage or even collapse. Understanding the loading and response of bridges during storms is critical to ensuring the resilience and reliability of transportation infrastructure in coastal regions. This study develops and applies a probabilistic bridge vulnerability framework that allows for coupled simulation of time-varying wave loading using OpenFOAM, dynamic structural response using OpenSees, and uncertainty quantification using Dakota. The framework is applied to evaluate bridge failure potential under wave and surge loading based on conditions observed during Hurricane Ike. Simulations were run on the Stampede2 system at TACC. Results indicate that waves with high peak periods and long wavelengths are the primary contributors to bridge instability. During Hurricane Ike, extreme wave loading exceeds the resistance of the typical bridge structure over 70% of the time, leading to sliding, uplifting, and overturning. Vertical stability of the bridge is most sensitive to uncertainties in the concrete density, while horizontal stability is most sensitive to uncertainties in the lateral stiffness of the bearings. Results from this research can inform the development of improved design standards for coastal bridges and/or the selection of appropriate countermeasures to improve bridge stability. The proposed computational framework can be applied across transportation systems to quantify failure probabilities and prioritize maintenance and retrofitting efforts for coastal bridges.Texas Advanced Computing Center (TACC
Intermanual Differences in movement-related interhemispheric inhibition
Interhemispheric inhibition (IHI) between motor cortical areas is thought to play a critical role in motor control and could influence manual dexterity. The purpose of this study was to investigate IHI preceding movements of the dominant and nondominant hands of healthy volunteers. Movement-related IHI was studied by means of a double-pulse transcranial magnetic stimulation protocol in right-handed individuals in a simple reaction time paradigm. IHI targeting the motor cortex contralateral (IHI(c)) and ipsilateral (IHI(i)) to each moving finger was determined. IHI(c) was comparable after the go signal, a long time preceding movement onset, in both hands. Closer to movement onset, IHI(c) reversed into facilitation for the right dominant hand but remained inhibitory for left nondominant hand movements. IHI(i) displayed a nearly constant inhibition with a trough early in the premovement period in both hands. In conclusion, our results unveil a more important modulation of interhemispheric interactions during generation of dominant than nondominant hand movements. This modulation essentially consisted of a shift from a balanced IHI at rest to an IHI predominantly directed toward the ipsilateral primary motor cortex at movement onset. Such a mechanism might release muscles from inhibition in the contralateral primary motor cortex while preventing the occurrence of the mirror activity in ipsilateral primary motor cortex and could therefore contribute to intermanual differences in dexterity
Data Assimilation Enhancements to Air Force Weathers Land Information System
The United States Air Force (USAF) has a proud and storied tradition of enabling significant advancements in the area of characterizing and modeling land state information. 557th Weather Wing (557 WW; DoDs Executive Agent for Land Information) provides routine geospatial intelligence information to warfighters, planners, and decision makers at all echelons and services of the U.S. military, government and intelligence community. 557 WW and its predecessors have been home to the DoDs only operational regional and global land data analysis systems since January 1958. As a trusted partner since 2005, Air Force Weather (AFW) has relied on the Hydrological Sciences Laboratory at NASA/GSFC to lead the interagency scientific collaboration known as the Land Information System (LIS). LIS is an advanced software framework for high performance land surface modeling and data assimilation of geospatial intelligence (GEOINT) information
The DONE framework: Creation, evaluation, and updating of an interdisciplinary, dynamic framework 2.0 of determinants of nutrition and eating.
The question of which factors drive human eating and nutrition is a key issue in many branches of science. We describe the creation, evaluation, and updating of an interdisciplinary, interactive, and evolving "framework 2.0" of Determinants Of Nutrition and Eating (DONE). The DONE framework was created by an interdisciplinary workgroup in a multiphase, multimethod process. Modifiability, relationship strength, and population-level effect of the determinants were rated to identify areas of priority for research and interventions. External experts positively evaluated the usefulness, comprehensiveness, and quality of the DONE framework. An approach to continue updating the framework with the help of experts was piloted. The DONE framework can be freely accessed (http://uni-konstanz.de/DONE) and used in a highly flexible manner: determinants can be sorted, filtered and visualized for both very specific research questions as well as more general queries. The dynamic nature of the framework allows it to evolve as experts can continually add new determinants and ratings. We anticipate this framework will be useful for research prioritization and intervention development
Introducing EDEN ISS - A European project on advancing plant cultivation technologies and operations
Plant cultivation in large-scale closed environments is challenging and several key
technologies necessary for space-based plant production are not yet space-qualified
or remain in early stages of development. The EDEN ISS project foresees
development and demonstration of higher plant cultivation technologies, suitable for
future deployment on the International Space Station and from a long-term
perspective, within Moon and Mars habitats. The EDEN ISS consortium will design
and test essential plant cultivation technologies using an International Standard
Payload Rack form factor cultivation system for potential testing on-board the
International Space Station. Furthermore, a Future Exploration Greenhouse will be
designed with respect to future planetary bio-regenerative life support system
deployments. The technologies will be tested in a laboratory environment as well as
at the highly-isolated German Antarctic Neumayer Station III. A small and mobile
container-sized test facility will be built in order to provide realistic mass flow
relationships. In addition to technology development and validation, food safety and
plant handling procedures will be developed. This paper describes the goals and
objectives of EDEN ISS and the different project phases and milestones.
Furthermore, the project consortium will be introduced and the role of each partner
within the project is explained
Support for e-cigarette regulations among Australian young adults
Background: Surveying support for various regulatory options relating to e-cigarettes can assist policymakers to identify those that have broad support and are therefore likely to be easier to implement. However, data on support for potential e-cigarette regulations in Australia are limited. To inform regulatory efforts, the present study assessed attitudes to the regulation of e-cigarettes among Australian young adults, the most prevalent users of e-cigarettes and therefore the most likely population segment to be affected by e-cigarette regulations. Methods: A total of 1116 Australians aged 18 to 25 years (59% female) completed an online survey where they were presented with various statements relating to the regulation of e-cigarettes and asked to report on the extent to which they agreed or disagreed with each. Statements presented either a restrictive or non-restrictive approach to e-cigarette regulation. Results: Across all statements, 10-22% of respondents responded "don't know" while 23-35% neither agreed nor disagreed, indicating general ambivalence. There was a moderate level of support (33-37%) for regulating e-cigarette sales/use and treating e-cigarettes like tobacco products. Only 20% of respondents were in favour of allowing the use of e-cigarettes in smoke-free areas. Smokers, e-cigarette users, and those who did not believe in the harms associated with e-cigarettes were typically less likely than other respondents to support restrictive approaches. Conclusions: The young Australian adults surveyed were somewhat supportive of restrictions around the sale and use of e-cigarettes, but generally opposed outright bans and any need for a prescription from a medical practitioner. Increasing awareness of the harms associated with the use of e-cigarettes represents a potential strategy to gaining regulatory support
Novel App knock-in mouse model shows key features of amyloid pathology and reveals profound metabolic dysregulation of microglia.
BACKGROUND: Genetic mutations underlying familial Alzheimer\u27s disease (AD) were identified decades ago, but the field is still in search of transformative therapies for patients. While mouse models based on overexpression of mutated transgenes have yielded key insights in mechanisms of disease, those models are subject to artifacts, including random genetic integration of the transgene, ectopic expression and non-physiological protein levels. The genetic engineering of novel mouse models using knock-in approaches addresses some of those limitations. With mounting evidence of the role played by microglia in AD, high-dimensional approaches to phenotype microglia in those models are critical to refine our understanding of the immune response in the brain.
METHODS: We engineered a novel App knock-in mouse model (App
RESULTS: Leveraging multi-omics approaches, we discovered profound alteration of diverse lipids and metabolites as well as an exacerbated disease-associated transcriptomic response in microglia with high intracellular Aβ content. The App
DISCUSSION: Our findings demonstrate that fibrillar Aβ in microglia is associated with lipid dyshomeostasis consistent with lysosomal dysfunction and foam cell phenotypes as well as profound immuno-metabolic perturbations, opening new avenues to further investigate metabolic pathways at play in microglia responding to AD-relevant pathogenesis. The in-depth characterization of pathological hallmarks of AD in this novel and open-access mouse model should serve as a resource for the scientific community to investigate disease-relevant biology
A TREM2-activating antibody with a blood-brain barrier transport vehicle enhances microglial metabolism in Alzheimer's disease models
van Lengerich et al. developed a human TREM2 antibody with a transport vehicle (ATV) that improves brain exposure and biodistribution in mouse models. ATV:TREM2 promotes microglial energetic capacity and metabolism via mitochondrial pathways. Loss-of-function variants of TREM2 are associated with increased risk of Alzheimer's disease (AD), suggesting that activation of this innate immune receptor may be a useful therapeutic strategy. Here we describe a high-affinity human TREM2-activating antibody engineered with a monovalent transferrin receptor (TfR) binding site, termed antibody transport vehicle (ATV), to facilitate blood-brain barrier transcytosis. Upon peripheral delivery in mice, ATV:TREM2 showed improved brain biodistribution and enhanced signaling compared to a standard anti-TREM2 antibody. In human induced pluripotent stem cell (iPSC)-derived microglia, ATV:TREM2 induced proliferation and improved mitochondrial metabolism. Single-cell RNA sequencing and morphometry revealed that ATV:TREM2 shifted microglia to metabolically responsive states, which were distinct from those induced by amyloid pathology. In an AD mouse model, ATV:TREM2 boosted brain microglial activity and glucose metabolism. Thus, ATV:TREM2 represents a promising approach to improve microglial function and treat brain hypometabolism found in patients with AD
Galaxy and Mass Assembly (GAMA): Variation in Galaxy Structure Across the Green Valley
Using a sample of 472 local Universe (z < 0.06) galaxies in the stellar mass range
10.25 < log M*/MG < 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is sub-divided into red, green and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies.
Using KiDS and VIKING derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells and signs of merger activity for all systems. We find a significant surplus of rings (2.3σ) and lenses (2.9σ) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3σ relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ∼ 44% which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ∼ 20 − 30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0σ surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley.
Key words: galaxies: elliptical and lenticular, cD – galaxies: spiral – galaxies: evo- lution – galaxies: star formation – galaxies: statistics – galaxies: structur
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