Detached Eddy Simulations of Hypersonic Transition

This slide presentation reviews the use of Detached Eddy Simulation (DES) of hypersonic transistion. The objective of the study was to investigate the feasibility of using CFD in general, DES in particular, for prediction of roughness-induced boundary layer transition to turbulence and the resulting increase in heat transfer

A qualitative assessment of barriers and facilitators of telemedicine volunteerism during the COVID-19 pandemic in India

Background: The COVID-19 pandemic further propelled the recent growth of telemedicine in low-resource countries, with new models of telemedicine emerging, including volunteer-based telemedicine networks. By leveraging existing infrastructure and resources to allocate health personnel more efficiently, these volunteer networks eased some of the pandemic burden placed on health systems. However, there is insufficient understanding of volunteer-based telemedicine models, especially on the human resources engagement on such networks. This study aims to understand the motivations and barriers to health practitioner engagement on a volunteer telemedicine network during COVID-19, and the mechanisms that can potentially sustain volunteer engagement to address healthcare demands beyond the pandemic. Methods: In-depth qualitative interviews were conducted with health practitioners volunteering on an Indian, multi-state telemedicine network during the COVID-19 pandemic. Data were analyzed using thematic content analysis methods. Results: Most practitioners reported being motivated to volunteer by a sense of duty to serve during the pandemic. Practitioners suggested organizational-level measures to make the process more efficient and facilitate a more rewarding provider–patient interaction. These included screening calls, gathering patient information prior to consultations, and allowing for follow-up calls with patients to close the loop on consultations. Many practitioners stated that non-financial incentives are enough to maintain volunteer engagement. However, practitioners expressed mixed feelings about financial incentives. Some stated that financial incentives are needed to maintain long-term provider engagement, while others stated that financial incentives would devalue the volunteer experience. Most practitioners highlighted that telemedicine could increase access to healthcare, especially to the rural and underserved, even after the pandemic. Practitioners also expressed an interest in continuing to volunteer with the network if the need arose again. Conclusion: Our study findings suggest that practitioners are highly intrinsically motivated to volunteer during large healthcare emergencies and beyond to address the healthcare needs of the underserved. Following the recommendations presented in the study, telemedicine networks can more successfully engage and maintain volunteer practitioners. Volunteer-based telemedicine networks have the potential to bridge shortages of health personnel in resource-constrained settings both in times of crises and beyond

Systems analysis of bioenergetics and growth of the extreme halophile Halobacterium salinarum

Halobacterium salinarum is a bioenergetically flexible, halophilic microorganism that can generate energy by respiration, photosynthesis, and the fermentation of arginine. In a previous study, using a genome-scale metabolic model, we have shown that the archaeon unexpectedly degrades essential amino acids under aerobic conditions, a behavior that can lead to the termination of growth earlier than necessary. Here, we further integratively investigate energy generation, nutrient utilization, and biomass production using an extended methodology that accounts for dynamically changing transport patterns, including those that arise from interactions among the supplied metabolites. Moreover, we widen the scope of our analysis to include phototrophic conditions to explore the interplay between different bioenergetic modes. Surprisingly, we found that cells also degrade essential amino acids even during phototropy, when energy should already be abundant. We also found that under both conditions considerable amounts of nutrients that were taken up were neither incorporated into the biomass nor used as respiratory substrates, implying the considerable production and accumulation of several metabolites in the medium. Some of these are likely the products of forms of overflow metabolism. In addition, our results also show that arginine fermentation, contrary to what is typically assumed, occurs simultaneously with respiration and photosynthesis and can contribute energy in levels that are comparable to the primary bioenergetic modes, if not more. These findings portray a picture that the organism takes an approach toward growth that favors the here and now, even at the cost of longer-term concerns. We believe that the seemingly "greedy" behavior exhibited actually consists of adaptations by the organism to its natural environments, where nutrients are not only irregularly available but may altogether be absent for extended periods that may span several years. Such a setting probably predisposed the cells to grow as much as possible when the conditions become favorable

More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: implications for pockmark field longevity

This paper is not subject to U.S. copyright. The definitive version was published in Geo-Marine Letters 31 (2011): 237-248, doi:10.1007/s00367-011-0228-0.Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes seafloor activity in the Belfast Bay, Maine nearshore pockmark field using (1) three swath bathymetry datasets collected between 1999 and 2008, complemented by analyses of shallow box-core samples for radionuclide activity and undrained shear strength, and (2) historical bathymetric data (report and smooth sheets from 1872, 1947, 1948). In addition, because repeat swath bathymetry surveys are an emerging data source, we present a selected literature review of recent studies using such datasets for seafloor change analysis. This study is the first to apply the method to a pockmark field, and characterizes macro-scale (>5 m) evolution of tens of square kilometers of highly irregular seafloor. Presence/absence analysis yielded no change in pockmark frequency or distribution over a 9-year period (1999–2008). In that time pockmarks did not detectably enlarge, truncate, elongate, or combine. Historical data indicate that pockmark chains already existed in the 19th century. Despite the lack of macroscopic changes in the field, near-bed undrained shear-strength values of less than 7 kPa and scattered downcore 137Cs signatures indicate a highly disturbed setting. Integrating these findings with independent geophysical and geochemical observations made in the pockmark field, it can be concluded that (1) large-scale sediment resuspension and dispersion related to pockmark formation and failure do not occur frequently within this field, and (2) pockmarks can persevere in a dynamic estuarine setting that exhibits minimal modern fluid venting. Although pockmarks are conventionally thought to be long-lived features maintained by a combination of fluid venting and minimal sediment accumulation, this suggests that other mechanisms may be equally active in maintaining such irregular seafloor morphology. One such mechanism could be upwelling within pockmarks induced by near-bed currents.Graduate support for Brothers came from a Maine Economic Improvement Fund Dissertation Fellowship

Influence of a dam on fine-sediment storage in a canyon river

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage ( similar to 17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon

Effects of Multimodal Load on Spatial Monitoring as Revealed by ERPs

While the role of selective attention in filtering out irrelevant information has been extensively studied, its characteristics and neural underpinnings when multiple environmental stimuli have to be processed in parallel are much less known. Building upon a dual-task paradigm that induced spatial awareness deficits for contralesional hemispace in right hemisphere-damaged patients, we investigated the electrophysiological correlates of multimodal load during spatial monitoring in healthy participants. The position of appearance of briefly presented, lateralized targets had to be reported either in isolation (single task) or together with a concurrent task, visual or auditory, which recruited additional attentional resources (dual-task). This top-down manipulation of attentional load, without any change of the sensory stimulation, modulated the amplitude of the first positive ERP response (P1) and shifted its neural generators, with a suppression of the signal in the early visual areas during both visual and auditory dual tasks. Furthermore, later N2 contralateral components elicited by left targets were particularly influenced by the concurrent visual task and were related to increased activation of the supramarginal gyrus. These results suggest that the right hemisphere is particularly affected by load manipulations, and confirm its crucial role in subtending automatic orienting of spatial attention and in monitoring both hemispaces

Centre–surround inhibition is a general aspect of famous-person recognition: evidence from negative semantic priming from clearly visible primes

A Centre-Surround Attentional Mechanism was proposed by Carr and Dagenbach (1990) to account for their observations of negative semantic priming from hard-to-perceive primes. The mechanism cannot account for the observation of negative semantic priming when primes are clearly visible. Three experiments (n = 30, 46, and 30) used a familiarity decision to names of famous people preceded by prime names of the same or different occupation. Negative semantic priming was observed at 150 or 200ms SOA with positive priming at shorter (50ms) and longer (1000ms) SOA. Experiment 3 verified that the primes were easily recognisable in the priming task at a SOA that yielded negative semantic priming, which cannot be predicted by the original Centre-Surround mechanism. A modified version is proposed that explains transiently negative semantic priming by proposing that Centre-Surround inhibition is a normal, automatically invoked aspect of the semantic processing of visually-presented famous names

Sedimentary framework of the inner continental shelf of Maine with special emphasis on commercial quality sand and gravel deposits and potentially economic heavy mineral placers

Maine Geological Survey, Open-File Report 97-4https://digitalmaine.com/mgs_publications/1613/thumbnail.jp

Sedimentary framework of the inner continental shelf of Maine with special emphasis on commercial quality sand and gravel deposits and potentially economic heavy mineral placers

Maine Geological Survey, Open-File Report 97-4https://digitalmaine.com/mgs_publications/1613/thumbnail.jp