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INTERNALLY-CURED LOW-CRACKING HIGH-PERFORMANCE CONCRETE (IC-LC-HPC) BRIDGE DECKS: DURABILITY AND CRACKING PERFORMANCE
No full textThe laboratory portion of this study investigates the effects of internal curing (IC) water in pre-wetted lightweight aggregates (LWA) between 8.2 and 9.0% and between 12.0 and 13.1% by weight of binder and total internal (TI) water in all aggregates between 3.4 and 12.5% by weight of binder on freeze-thaw durability, scaling resistance, shrinkage, and ion transport properties of concrete mixtures with different binder compositions (100% portland cement or a ternary composition with 30% slag cement and 3% silica fume as partial replacements for portland cement [by total weight of cementitious materials]), paste as a percentage of concrete volume (23.7, 24.6, 26.7, or 33.7%), and water-to-cementitious material ratios (w/cm, 0.45 or 0.41). Normalweight aggregates consisted of three types of coarse aggregates and river sand.The results show that for paste contents between 23.7 and 33.7% of concrete volume, the freeze-thaw durability of internally-cured concrete mixtures is a function of the percentage of IC water by the weight of binder, rather than total IC water per unit volume of concrete; all IC mixtures assessed for freeze-thaw durability in accordance with ASTM C666-Procedure A exhibited durability factors below 90% and failed the freeze-thaw test and would not be considered acceptable under MnDOT specifications, while some mixtures at w/c ratio of 0.45 and all mixtures at a w/c ratio of 0.41satisfied the requirements of ASTM C666-Procedure B and KTMR-22 and would be considered acceptable under KDOT specifications. The results also demonstrate that the freeze-thaw resistance of the mixtures decreased markedly when the TI water exceeded 12.0% by the weight of binder. Scaling test results show that as the paste content increases from 23.7 to 33.7%, the scaling resistance of the specimens decreases. At a w/cm ratio of 0.45 and a paste content of 23.7%, mixtures with an IC water content of 8.8% passed the scaling test; at a w/cm ratio of 0.41 and a paste content of 23.7%, mixtures with IC water contents less than or equal to 13% passed the scaling test. None of the mixtures with a paste content of 33.7% passed the scaling test at either w/cm ratio. Moreover, for a given binder composition and type of coarse aggregate, increased TI water resulted in higher scaling resistance. The type of coarse aggregate also had effects on scaling resistance. The ternary mixtures with granite as the coarse aggregate, had lower mass losses than the ternary mixtures with low-absorption limestone and similar quantities of TI water. As the TI water content increased, shrinkage decreased for concretes with both binder compositions. Mixtures with IC water exhibited more expansion at the end of the curing period than mixtures with no IC water. Increases in the TI water content in mixtures did not affect the rapid chloride permeability or surface resistivity measurements, while the binder composition did, with the ternary mixtures, on average, showing higher and lower SRM and RCP values, respectively, than mixtures containing 100% portland cement.The second portion of the study involved the construction, crack surveys, and evaluation of 12 bridge decks (nine in Minnesota and three in Kansas) containing IC water and supplementary cementitious materials (SCMs) that were constructed between 2016 and 2021 following IC-LC-HPC specifications (of Minnesota or Kansas) and two associated Control decks without IC. The decks were monolithic with the exception of three of the Minnesota decks, which had overlays. The results show that the use of overlays on bridge decks results in high crack densities and should be avoided. Low-cracking bridge decks require concrete with a paste content of 27.2% or less based on concrete volume. Paste contents above 27.2% correlate with increased cracking, and for decks with paste contents greater than 27.2%, the addition of IC and SCMs does not overcome the negative effects of high paste content. The results also indicate that the combination of low paste, internal curing, and good construction procedures offer the potential to reduce cracking. Under circumstances, good construction practices are needed for low-cracking decks. If poor construction practices are employed, even decks with low paste content and IC can exhibit high cracking and scaling damage
Use of a Mobile-Assisted Telehealth Regimen to Increase Exercise in Transplant Candidates: A Home-Based Prehabilitation Pilot and Feasibility Trial
No full textINTRODUCTION:
Physical fitness assessed by the Liver Frailty Index (LFI) and 6-minute walk test (6MWT) informs the prognosis of liver transplant candidates, although there are limited data on its reversibility after prehabilitation. On a home-based exercise trial, we aimed to improve LFI and 6MWT and to investigate trial feasibility and intervention adherence.
METHODS:
Liver transplant candidates with cirrhosis wore a personal activity tracker and used Exercise and Liver FITness app for 14 weeks, including a 2-week technology acclimation run-in. The 12-week intervention consisted of Exercise and Liver FITness app plus personal activity tracker and 15-/30-minute weekly calls with a physical activity coach aiming to complete ≥2 video-training sessions/week, or ≥500 step/d baseline increase for ≥8 weeks. We defined feasibility as ≥66% of subjects engaging in the intervention phase and adherence as ≥50% subjects meeting training end point.
RESULTS:
Thirty-one patients (61 ± 7 years, 71% female, model for end-stage liver disease 17 ± 5, ∼33% frail) consented and 21 (68%) started the intervention. In the 15 subjects who completed the study, LFI improved from 3.84 ± 0.71 to 3.47 ± 0.90 (P = 0.03) and 6MWT from 318 ± 73 to 358 ± 64 m (P = 0.005). Attrition reasons included death (n = 4) and surgery (n = 2). There was 57% adherence, better for videos than for walking, although daily steps significantly increased (3,508 vs baseline: 1,260) during best performance week. One adverse event was attributed to the intervention.
DISCUSSION:
Our clinical trial meaningfully improved LFI by 0.4 and 6MWT by 41 m and met feasibility/adherence goals. In-training daily step increase supported physical self-efficacy and intervention uptake, but maintenance remained a challenge despite counseling
shá bik’ehgo (in the path of the sun)
No full textshá bik’ehgo (in the path of the sun) is an exhibition presenting an all-encompassing landscape navigating time, place, and story that encapsulates Diné notions of hózhó and continual life. This paper will address foundational thoughts, reflections on the creative process, the work itself, and the gallery installation
Analysis of Spinal Rod Deformation After Cutting with a Surgical Rod Cutter
No full textScoliosis, a deformity characterized by an abnormal curvature of the spine, requires various treatment approaches depending on the severity of the condition, including surgical or non-surgical options. Surgical procedures, often involving the use of spinal fusion rods, play a crucial role in correcting spinal deformities. However, the process of cutting these rods with a surgical rod cutter may introduce deformations at the cut ends, potentially leading to complications and compromised treatment outcomes.This paper presents an analysis of the deformation observed in scoliosis rods after they have been cut using a surgical rod cutter. Identification of the extent and characteristics of deformations that occur during the cutting process will be assessed, as well as determining the point at which deformation ceases along the length of the rods.To achieve this objective, photogrammetry and three-dimensional modeling techniques were employed. Photogrammetry was used to create accurate three-dimensional models of these rods from two-dimensional photographs, providing a detailed representation of the deformed rod ends. Precise measurements and analysis were then performed to quantify and characterize the deformations.Three different diameters (4.75mm, 5.5mm, and 6.0mm) of two different types of metal rods (Titanium and Cobalt Chrome) resulting in six different experimental groups, were analyzed. Analysis of the deformed rod ends involved assessing the deviating angle of the plasticly deformed region of the rod and the roundness of the deformed cross sections. The higher diameter the rod, the more deformation was experienced. Cobalt chrome also experienced more angular deviation and lower roundness compared to its Titanium counterpart. Once all angular deviations reached 0 degrees and roundness values reached above 0.985, there was confidence there was minimal deformation at that spot. For the 4.75 mm and 5.5 mm Ti rods, 4 mm of space is required between the edge of the cut to where there is minimal deformation. For the 6.0 mm Ti, and all CoCr rods, 5 mm of space is needed. These data remain consistent with metal deformation studies, which show larger diameter rods deforming more than smaller ones, as well as CoCr deforming more than Ti. It is crucial to leave the required room to decrease the chances of instrument failure.This study contributes to the ongoing improvement of surgical techniques and treatment outcomes in scoliosis management. The analysis of deformation in scoliosis rods after cutting provides important information for optimizing surgical procedures and enhancing the long-term success of spinal fusion treatments
Alarm communication predates eusociality in termites
Get PDFTermites (Blattodea: Isoptera) have evolved specialized defensive strategies for colony protection. Alarm communication enables workers to escape threats while soldiers are recruited to the source of disturbance. Here, we study the vibroacoustic and chemical alarm communication in the wood roach Cryptocercus and in 20 termite species including seven of the nine termite families, all life-types, and all feeding and nesting habits. Our multidisciplinary approach shows that vibratory alarm signals represent an ethological synapomorphy of termites and Cryptocercus. In contrast, chemical alarms have evolved independently in several cockroach groups and at least twice in termites. Vibroacoustic alarm signaling patterns are the most complex in Neoisoptera, in which they are often combined with chemical signals. The alarm characters correlate to phylogenetic position, food type and hardness, foraging area size, and nesting habits. Overall, species of Neoisoptera have developed the most sophisticated communication system amongst termites, potentially contributing to their ecological success
Using machine learning to differentiate between enzymatic and non-enzymatic metalloprotein sites
No full textEnzymes are biological catalysts with exceptional product specificity and the potential for unmatched speed-up of reaction rates. Although current wet-lab techniques are capable of detecting enzyme activity for over 8,000 biochemical reactions, the experimental discovery of new enzymes continues to be time consuming and expensive. Computational tools can offer affordable options that enable the discovery of enzymes capable of advancing healthcare, environmental remediation, and industrial processes.Herein, I describe the development of a computational tool for predicting enzyme activity, including catalytic mechanisms that have not yet been discovered by evolution. I start with a recent literature review to identify the most successful machine learning methods for enzymatic applications. Using the most popular techniques, decision tree ensemble algorithms and structure-based features, I developed a ML-based tool that uses metalloprotein sites, which limited differences in positive and negative data that were unrelated to catalysis (Chapter 2). To train and evaluate ML models, I made the largest set of non-redundant, catalytically labeled metalloprotein sites to date. The developed model, MAHOMES, outperformed alternative methods when evaluated on the same metalloproteins with a 90% recall and 92% precision. The most important features for making predictions were related to electrostatics and pocket lining. Further benchmarking found MAHOMES required sub-angstrom precision.To enable the same performance on computationally generated structures, improvements targeting the required sub-angstrom precision were made to create MAHOMES II (Chapter 3). The updated model had a 92% recall, 94% precision, and increased predictive convergence when given different structural inputs of the same site. On a test of computationally generated sites with no evolutionary relationship to any previously used metalloproteins, MAHOMES II was 90 - 97.5% depending generated site’s confidence. The correctly predicted enzyme sites included 39 biochemical reactions that were not included in the training data. By deploying MAHOMES II on a webserver, I anticipate that this work will catalyze the community’s ability to find novel enzymes and improve enzyme design success rates
Hybrid Racial Identities of Asian/Black, Asian/Brown, and Asian/White Mixed-Race Individuals: A Comparative Analysis
No full textThis study elaborates challenges faced and strategies deployed by Asian/Black, Asian/Brown, and Asian/White mixed-race individuals in asserting hybrid racial identities. Specifically, I ask: What factors influence mixed-race Asian Americans’ assertion of racial identities? When comparing Asian/Black, Asian/Brown, and Asian/White individuals, what different strategies and challenges emerge? To address these questions, I conducted semi-structured interviews with 34 participants, and four major points of comparison emerged. First, Asian/Black participants’ assertions of multiracial or Asian identity were more likely to be constrained by perceptions of their appearance because of their perceived blackness. In comparison, Asian/Brown and Asian/White participants’ appearances were seen as more ambiguous, giving them more flexibility to identify multiracially, as Asian, or as some other racial option. Second, Asian/Black and Asian/Brown participants’ encounters with racism tended to reinforce mixed-race identity, whereas Asian/White participants’ racist interactions were more likely to strengthen Asian identification. Third, Asian/Black and Asian/Brown participants’ family members were more likely to engage in conversation to support mixed-race identification. However, Asian/White participants frequently faced derogatory comments and othering behavior from White family members, which tended to increase self-perceptions of being racially Asian. Fourth, Asian/Black and Asian/Brown participants tended to have less cultural knowledge of their Asian heritages, yet this generally did not prevent them from asserting hybrid Asian identities. On the other hand, Asian/White participants felt cultural knowledge was necessary to assert an Asian identity, and they generally had the option of gaining cultural membership
Perceptions and Prototypes of Racial Discrimination Across Contexts
No full textPerceptions of group-level racial discrimination have been shown to differ depending on whether the target of discrimination belongs to the perceiver’s ingroup or outgroup (e.g., Carter & Murphy, 2015; Craig & Richeson, 2017; Norton & Sommers, 2011). These perceptions have also been shown to vary based on the domain in which discrimination is considered (Peacock & Biernat, 2023). At the same time, people tend to have prototypes of discrimination such that people in power discriminate against those without power (e.g., Inman & Baron, 1996). However, limited research has examined racial discrimination perceptions and prototypes across varying contexts. The goal of the current studies is to close this gap in the literature. With a majority-White sample (N = 287), Study 1 examined perceptions of racial discrimination across 25 contexts, including ratings of 10 manifestations of discrimination (e.g., “White individuals discriminating against Black individuals”). Participants also chose one of the 10 manifestations as their prototype of discrimination for that context. Perceptions of discrimination differed by context and manifestation, and prototypes of discrimination differed by context, with considerable acknowledgement that Black Americans face discrimination (perpetrated by White individuals and social systems), but also some suggestion that discrimination simply does not occur. Study 2 was a replication that included Black and non-Black Hispanic participants (N = 285). Discrimination perceptions again varied by context and manifestation, but chosen prototypes were not context dependent (anti-Black and anti-Latino discrimination, both perpetrated by White actors and social systems) were widely perceived as prototypical across contexts. In both studies, perceiver effects, and particularly conservative political ideology, predicted lower endorsement of these prototypical forms of discrimination. The studies suggest that perceptions of racial discrimination are nuanced, and sensitive to context, manifestation, and perceiver effects. Specific measurement of type of discrimination and the context in which it occurs can provide a deeper understanding of group-based similarities and differences in the perception of discrimination
BDDC algorithms for the PDEs with HDG discretizations
No full textThe balancing domain decomposition by constraints methods (BDDC) is one of the most popular nonoverlapping domain decomposition methods. In this dissertation, the BDDC preconditioned conjugate gradient (CG) methods are applied to solve the symmetric saddle point problem such as Stokes problem and Brinkman problem with Hybridizable Discontinuous Galerkin (HDG) discretizations. Edge/face average constraints are enforced across the subdomain interface to ensure that the BDDC preconditioned CG iterations stay in a special subspace, where the preconditioned operator is positive definite. The condition number estimate is given for different choices of stabilization parameters in Stokes problem. Deluxe scaling and adaptively chosen primal constraints are introduced in the Brinkman problem to ensure the condition number is uniformly bounded.The BDDC preconditioned GMRES method is developed for solving the linear system derived from the HDG discretization of Advection-diffusion equations and the Oseen equation of incompressible flow. These problems are either nonsymmetric positive definite or can be reduced to a nonsymmetric positive definite problem in a special subspace. Additional edge constraints are introduced to improve the efficiency. The convergence rates depend on the viscosity. For large viscosity, if the subdomain size is small enough, the number of iterations is independent of the number of subdomains and depends only slightly on the subdomain problem size. The convergence deteriorates when the viscosity decreases
Are We There Yet: Assessing Trajectories of Two Restored Prairies to Target Native Prairies over a Decadal Time Frame
No full textTallgrass prairie restoration aims to increase biodiversity, reinstate natural ecosystem functioning, and increase wildlife habitat in lands that have been degraded by human activity. Ecological restoration often involves identifying intact target communities that can be used as a reference for what a successfully restored community looks and functions like. The purpose of this study was to use the International Society for Ecological Restoration standards for ecosystem restoration to assess the compositional and functional similarities and differences between two restorations established under contrasting climate conditions to two nearby native prairie targets. I leveraged a sequential restoration experiment initiated in 2010 at the Konza Prairie Biological Station to compare trajectories of plant community development and ecosystem functioning in restorations established under different planting-year climate conditions in relation to nearby native prairie targets. Plant species composition, functional group cover based on plant life history traits, and aboveground net primary productivity (ANPP) were measured at the same scales in the restored and native prairies. Indicator species analysis was performed to identify species-level dissimilarities between the composition of the plant communities. The restoration sequences, while distinct from one another due to the effects of planting-year precipitation, were more similar to one another than they were to either target in terms of species and functional group composition. Functionally, the restorations differed from one another in their response to precipitation, with the prairie established in a drought year being less sensitive to interannual variability in precipitation than the prairie established in an average rainfall year. The two targets were quite dissimilar from one another. The reference target closest to the restorations and on the most similar soil was more like the restorations than the other native prairie target in terms of species composition, functional composition, diversity, and evenness. Species diversity and evenness was higher in this closest target, while species richness was highest in the further target. Both reference systems had higher species richness than the restorations, with the prairie established in the average rainfall year having a significantly lower total species richness. Indicator species for the restorations were all species planted during restoration, whereas the native prairie communities had a larger number of unique species not present in the restorations. In conclusion, even with a small sown species pool, the development of restored prairie approached native prairies on a decadal time scale to contain higher diversity than functionally similar native prairie, but targets can be dissimilar from one another even in the same region and under the same management regime. Knowledge of plant composition in targets, compared to restored prairies, can inform management decisions by revealing satellite species that could be overseeded to steer restoration trajectories closer to native communities