University of Oklahoma
  • Norman, OK, United States
Recent publications
Cancer has been a serious threat to human health. Among drug delivery carriers, protein nanoparticles are unique because of their mild and environmentally friendly preparation methods. They also inherit desired characteristics from natural proteins, such as biocompatibility and biodegradability. Therefore, they have solved some problems inherent to inorganic nanocarriers such as poor biocompatibility. Also, the surface groups and cavity of protein nanoparticles allow for easy surface modification and drug loading. Besides, protein nanoparticles can be combined with inorganic nanoparticles or contrast agents to form multifunctional theranostic platforms. This review introduces representative protein nanoparticles applicable in cancer theranostics, including virus-like particles, albumin nanoparticles, silk protein nanoparticles, and ferritin nanoparticles. It also describes the common methods for preparing them. It then critically analyzes the use of a variety of protein nanoparticles in improved cancer imaging and therapy.
The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.
The ATLAS experiment at the Large Hadron Collider has a broad physics programme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accurate datasets of simulated Monte Carlo events. Detector simulation with Geant4 is accurate but requires significant CPU resources. Over the past decade, ATLAS has developed and utilized tools that replace the most CPU-intensive component of the simulation—the calorimeter shower simulation—with faster simulation methods. Here, AtlFast3, the next generation of high-accuracy fast simulation in ATLAS, is introduced. AtlFast3 combines parameterized approaches with machine-learning techniques and is deployed to meet current and future computing challenges, and simulation needs of the ATLAS experiment. With highly accurate performance and significantly improved modelling of substructure within jets, AtlFast3 can simulate large numbers of events for a wide range of physics processes.
Background Prior research suggests that dysbiotic gut microbiomes may contribute to elevated health risks among American Indians. Diet plays a key role in maintaining a healthy gut microbiome, yet suboptimal food environments within American Indian communities make obtaining nutritious food difficult. Objective This project characterizes the retail food environment within a rural tribal community, focused on the availability of foods that enhance the health and diversity of the gut microbiome, as well as products that reduce microbiome health (alcohol and tobacco). Design Audits were conducted of all retail stores that sell food within nine communities within the Cheyenne & Arapaho Tribal Jurisdictional Area in western Oklahoma. Main measures Freedman Grocery Store Survey. Key results Alcohol and tobacco were generally far more available in stores than foods that support a healthy gut microbiome, including fruits, vegetables, lean meats, and whole grain bread. Out of the four store types identified in the study area, only supermarkets and small grocers offered a wide variety of healthy foods needed to support microbiota diversity. Supermarkets sold the greatest variety of healthy foods but could only be found in the larger communities. Convenience stores and dollar stores made up 75% of outlets in the study area and offered few options for maintaining microbiome health. Convenience stores provided the only food source in one-third of the communities. With the exception of small grocers, alcohol and tobacco products were widely stocked across all store types. Conclusions The retail food environment in the Cheyenne & Arapaho Tribal Jurisdictional Area offered limited opportunities for maintaining a healthy and diverse microbiome, particularly within smaller rural communities. Additional research is needed to explore the relationship between food environment, dietary intake, and microbiome composition. Interventions are called for to increase the availability of “microbe-friendly” foods (e.g., fresh produce, plant protein, fermented and high fiber foods) in stores.
High-quality lead selenide (PbSe) epitaxial films are key to improving the performance of mid-wave infrared (MWIR) optoelectronics. Herein, high-quality PbSe epitaxial films with 30 μm in thickness were successfully fabricated by chemical bath deposition (CBD), and the growth modes were described by investigating the effect of growth temperature and [OH⁻]/[Pb²⁺] on the morphologies and microstructural evolution of PbSe epitaxial films. Furthermore, a new pre-orientation induced oriented attachment (POIOA) growth mechanism was proposed to illustrate the texture of close-packed PbSe (111) nano-pyramids. It was found that the film orientation is determined by the epitaxial seed layer and the growth mechanism varies with temperature changing from the low-temperature cluster mechanism (LTCM, < 30 °C) to the middle-temperature POIOA (30–60 °C) mechanism, and finally dominated by high-temperature ion-by-ion (HTIBI, > 60 °C) which was crucial for single-crystal PbSe deposition. The increased [OH⁻]/[Pb²⁺] can significantly decrease the transformation-temperature of the growth mechanism, and the single-crystal film can be obtained as the temperature reaches 40 °C. Eventually, a microstructural zone model of films as a function of temperatures and [OH⁻]/[Pb²⁺] was established.
In democratic backsliding, threats to democracy no longer come from abrupt, radical ruptures promoted by those who are close to, but outside of, state power. They come from those who win elections and, while in office, systematically undermine accountability institutions and minority rights. Zakaria used the term illiberal democracies to describe these regimes where popularly elected governments are divorced from political freedoms and accountability. Law is not absent from these stories. Rising autocrats seek to make their moves legal and use law—as a weapon or as a shield—in attempts to amass power and suppress opposition. Authors coined the term autocratic legalism to describe these power-grabbing tactics that operate through law. Others use different concepts, such as constitutional retrogression or abusive constitutionalism. I review this growing body of literature and outline a research agenda on the encounters between law and illiberalism. Expected final online publication date for the Annual Review of Law and Social Science, Volume 18 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
To reduce peak demand and/or energy cost for residential buildings, optimal precooling strategies are becoming important as an alternative to rule-based precooling strategies that are intuitive but may not be optimal. Since precooling optimization is heavily dependent on a variety of factors such as the home thermal properties, HVAC system, weather, thermal comfort criteria, and utility rate structure, the individual and collective impact of these factors on precooling performance needs to be analyzed. In addition, since the indoor air temperature is affected by heat transfer to and from the interior wall surface, performance analysis in view of the interior wall surface temperature is also essential. Therefore, in this paper, an optimal precooling strategy that accounts for the aforementioned factors and utilizes a second-order thermal network model, is proposed. With this strategy, the HVAC on/off control signal that minimizes 24-hour energy cost while maintaining thermal comfort, is determined. Through extensive simulations, it is found that the proposed optimal precooling strategy is able to adapt to changing conditions and that having a sufficiently low interior wall surface temperature during precooling is critical for avoiding expensive on-peak operation. The reason for the latter is that such a temperature indicates that enough “cooling energy” has been stored. It is also found that weather has the most dominant impact on the precooling performance, followed by home thermal condition, with the rated cooling capacity and utility rate structure having the least impact.
In this study, we have assessed the petrographical and petrophysical characteristics of the progradational, syn-rift Middle Miocene Rahmi sandstone gas reservoir (Lower Kareem Formation) from the East Matr and Amal hydrocarbon fields, southern Gulf of Suez by integrating sidewall cores and wireline logs. We interpreted a reservoir gas gradient of around 0.09 psi/ft from the downhole pressure measurements. Based on well log-based petrophysical analyses, we interpreted that the Rahmi reservoir in the East Matr field has a 0.10-0.18 v/v total porosity, 0.08-0.14 v/v effective porosity, 0.08-0.17 v/v shale volume along with water saturation ranging between 0.09-0.32 v/v. The correlated reservoir in the Amal field is observed to have higher porosities (0.17-0.22 v/v total porosity and 0.15-0.19 v/v effective porosity), although it exhibits higher water saturation (0.38-0.54 v/v). The reservoir consists of very fine to coarse grained, poorly to moderately sorted, subangular to subrounded, poorly cemented and moderately compacted sublithic, subarkosic and arkosic arenites with moderate to good intergranular porosity. Abundant lithic fragments and poor textural maturity of the Rahimi sandstones imply a high energy shoreface depositional environment in close proximity to the hinterland. Porosity reduction is attributed to dolomite cementation, kaolinite, formation of pseudomatrix by mechanical compaction of argillaceous lithics, and quartz overgrowth. Long and concavo-convex intergranular contacts indicate that silica needed for quartz cementation was derived by moderate degree of chemical compaction of the quartz grains. Partial to near-complete dissolution of the labile grains (feldspar and lithics) and dolomite attributed to the reservoir quality improvement. Scattered dolomite cements prevented more severe mechanical and chemical compaction.
Bacterial drug-efflux transporters act synergistically with diffusion barriers of cellular membranes and other resistance mechanisms to protect cells from antibiotics and toxic metabolites. Their critical roles in clinical antibiotic and multidrug resistance are well established. In addition, a large body of evidence has been accumulated in support of their important contributions to bacterial growth and proliferation during infections. However, how these diverse functions of drug transporters are integrated at the level of bacterial cell physiology remains unclear. This opinion briefly summarizes the current understanding of substrate specificities and physiological roles of drug-efflux pumps from Resistance–Nodulation–Division (RND) superfamily of proteins in two ESKAPE pathogens Pseudomonas aeruginosa and Acinetobacter baumannii. Based on the analysis of phenotypic and transcriptomic studies in vitro and in vivo, we propose that RND pumps of Gram-negative bacteria fall into three categories: constitutively expressed, regulated, and silent. These three categories of efflux pumps participate in different physiological programs, which are not involved in the central metabolism and bacterial growth.
Characterizing error structures in precipitation products not only facilitates their proper applications for scientific and practical purposes but also helps improve their retrieval algorithms and processing methods. Despite the fact that multiple precipitation products have been assessed in the literature, factors that affect their error structures remain inadequately addressed. By interpreting 60 binary decision trees, this study disentangles the error characteristics of precipitation products in terms of their spatiotemporal patterns and geographical factors. Three independent precipitation products - two satellite-based and one reanalysis datasets: the Integrated Multi-satellitE Retrievals for GPM (Global Precipitation Measurement) late run (IMERG-L), Soil Moisture to Rain-Advanced SCATterometer (SM2RAIN-ASCAT), and the Modern-Era Retrospective analysis for Research and Applications, Version 2 uncorrected precipitation output (MERRA2-UC), are evaluated across the contiguous United States from 2010 to 2019. The ground-based Stage IV precipitation dataset is used as the ground truth. Results indicate that the MERRA2-UC outperforms the IMERG-L and SM2RAIN-ASCAT with higher accuracy and more stable interannual patterns for the analysis period. Decision trees cross-assess three spatiotemporal factors and find that the underestimation of MERRA2-UC occurs in the east of the Rocky Mountains, and SM2RAIN-ASCAT underestimates precipitation over high latitudes, especially in winter. Additionally, the decision tree method ascribes system errors to nine different geographical characteristics, of which the distance to the coast, soil type, and DEM are the three dominant features. On the other hand, the land cover type, topography position index, and aspect are three relatively weak factors.
Background The COVID-19 pandemic and associated policy responses have interrupted services, increased financial stress, and driven social isolation, with acute impacts for adolescents. This study explores relationships between gender, COVID-19 vulnerability, social protection, and adolescent wellbeing in three diverse contexts: Ethiopia, Jordan, and Palestine. Methods This study presents findings from a quantitative phone survey with adolescents in Ethiopia, Jordan, and Palestine (n = 5752) on household-level vulnerability to COVID-19-related shocks, household-level social protection (cash transfers or food aid), and locally adapted outcome measures designed to capture the gendered impacts of COVID-19 (collected between November 22, 2020 and February 25, 2021). We examine the relationship between each outcome and household-level COVID-19 vulnerability and social protection (and their interaction) using multivariate regressions, adjusting for adolescent and household characteristics. Findings For all adolescents, increased vulnerability to COVID-19-related shocks is associated with worse outcomes for resilient coping and time spent on domestic tasks and care work. Across samples, girls spent over two additional hours on domestic and care work compared to boys. Girls in more vulnerable households experienced greater gendered constraints on behaviour. We find no association between receipt of social protection and adolescent wellbeing, and find that it only moderates the effect of COVID-19 vulnerability for less vulnerable households. Disability status, being out of school, and experiencing child marriage are also associated with adverse outcomes. Interpretation Our study highlights that the pandemic has exacerbated underlying gender inequalities across adolescents in three very different settings, and that existing social safety nets are not adequate to fully address these impacts, particularly for the most vulnerable. Funding This work was supported by UK aid through a grant from the Foreign, Commonwealth & Development Office to the Gender and Adolescence: Global Evidence (GAGE) longitudinal research study; the EMERGE project (Bill & Melinda Gates Foundation grants: OPP1163682 and INV018007; PI Anita Raj) and the World Health Organization (WHO) Regional Office for the Eastern Mediterranean.
Cultural intelligence (CQ) is an increasingly valuable asset for managers, employees, entrepreneurs, and their organizations. While there is now considerable evidence for its benefits, knowledge remains cloudy surrounding its antecedents. Drawing on identity theory, we develop a model unpacking the relationship between cross-cultural experience—a core antecedent with mixed findings in extant research—and CQ. We advance multicultural identity as a pivotal intervening variable and probe the role of self-verification striving as an identity-based boundary condition. Across two interlocking studies, we find evidence for how CQ can be cultivated from a range of increasingly common forms of cross-cultural experiences. In doing so, we shed light on the mixed results in prior research and provide key implications for future research; namely, multicultural identity helps to better account for when and how individuals translate their cross-cultural experiences into CQ.
Public diplomacy (PD) as a field of study lacks both theoretical and methodological depth. Although a wide range of methodology is used to study the field, case studies, surveys, and content analyses are the most frequently used. While these methods are necessary to study PD, they lack the ability to establish a causal relationship between variables. A lot of attention in PD scholarship is now on digitalization and the use of social media in PD. Similarly, a significant portion of scholarship is devoted to analyzing PD messages. This article argues that experimental methodology is an important but under-utilized tool for scholars in the field. Controlled experiments are believed to be the best method to determine cause-and-effect relationships among variables. The article aims to help scholars of the discipline conduct controlled experiments that further their understanding of PD campaigns and messages. It does so by detailing experiments as a methodology, indicating what type of research questions can be answered by this approach and how to carry out an experiment.
Three types of previously used numerical methods are revisited for computing the streamfunction ψ and velocity potential χ from the horizontal velocity v in limited domains. The first type, called the SOR-based method, uses a classical successive over-relaxation (SOR) scheme to compute ψ (or χ) first with an arbitrary boundary condition (BC) and then χ (or ψ) with the BC derived from ν. The second type, called the spectral method, uses spectral formulations to construct the inner part of (ψ, χ)—the inversion of (vorticity, divergence) with a homogeneous BC, and then the remaining harmonic part of (ψ, χ) with BCs from ν. The third type, called the integral method, uses integral formulas to compute the internally induced (ψ, χ)—the inversion of domain-internal (vorticity, divergence) using the free-space Green’s function without BCs and then the remaining harmonic ψ (or χ) with BCs from v minus the internally-induced part. Although these methods have previously been successfully applied to flows in large-scale and synoptic-scale domains, their accuracy is compromised when applied to complex flows over mesoscale domains, as shown in this paper. To resolve this problem, two hybrid approaches, the integral-SOR method and the integral-spectral method, are developed by combining the first step of the integral method with the second step adopted from the SOR-based and spectral methods, respectively. Upon testing these methods on real-case complex flows, the integral-SOR method is significantly more accurate than the integral-spectral method, noting that the latter is still generally more accurate than the three previously-used methods. The integral-SOR method is recommended for future applications and diagnostic studies of complex flows.
Unstable foams quickly lose their valuable properties. This article presents the results of an experimental study conducted on the drainage of aqueous foams at elevated pressures. During the investigation, the foam was generated and circulated in a flow loop. First, its rheology was measured to ensure proper foam generation. Then, its drainage was determined by trapping it in a vertical test section and measuring the pressure profile. The results show that increasing pressure reduces foam drainage, indicating foam stabilization at high pressures. In addition, column height decreases foam drainage because the drainage rate varies along the axis of the column.
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Samuel Cheng
  • School of Electrical and Computer Engineering
Caryn C. Vaughn
  • Oklahoma Biological Survey
Pascal Nitiema
  • Division of Management Information Systems
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