College of Science and Engineering
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Item 3D Nanomolding and Fluid Mixing in Micromixers with Micro-patterned Microchannel Walls(Springer, 2017-01) Farshchian, Bahador; Amirsadeghi, Alborz; Choi, Junseo; Park, Daniel S.; Kim, Namwon; Park, SunggookMicrofluidic devices where the microchannel walls were decorated with micro and nanostructures were fabricated using 3D nanomolding. Using 3D molded microfluidic devices with microchannel walls decorated with microscale gratings, the fluid mixing behavior was investigated through experiments and numerical simulation. The use of microscale gratings in the micromixer was predicated by the fact that large obstacles in a microchannel enhances the mixing performance. Slanted ratchet gratings on the channel walls resulted in a helical flow along the microchannel, thus increasing the interfacial area between fluids and cutting down the diffusion length. Increasing the number of walls decorated with continuous ratchet gratings intensified the strength of the helical flow, enhancing mixing further. When ratchet gratings on the surface of the top cover plate were aligned in a direction to break the continuity of gratings from the other three walls, a stack of two helical flows was formed one above each other. This work concludes that the 3D nanomolding process can be a cost-effective tool for scaling-up the fabrication of microfluidic mixers with improved mixing efficiencies.Graphical abstractIn this paper we show that a micromixer with patterned walls can be fabricated using 3D nanomolding and solvent-assisted bonding to manipulate the flow patterns to improve mixing.Item A Collective Impact Model Towards Increasing STEM Major Student Retention(Texas State University, The Education Institute, 2020-02) Martinez Ortiz, Araceli; Novoa, Clara; Sriraman, VedaramanThis article presents the research findings of a multidisciplinary team's collective research effort at one university over a five-year period as funded by the National Science Foundation's Improving Undergraduate STEM Education (IUSE) program. A collaborative learning and retention action research effort at a large Hispanic Serving Institution is analyzed using mixed methods to document the power of collective impact as the foundation for a learning support model for students historically underrepresented majoring in science, technology, engineering and mathematics (STEM) academic programs. The actions of the team of researchers are presented to describe the Rising Stars Collective Impact model and the impacts achieved. This is a model that aligns objectives, intervention efforts, and reports collective results. The long-term goals of the Rising Stars Collective Impact multiple programs managed by the funded program team included the following: (a) to improve the campus sense of community for students historically under-represented in STEM, (b) to establish innovative and robust STEM education research-based practices to support critical skill attainment for students, and (c) to support faculty understanding of the funds of knowledge of diverse students. The positive student retention and success impacts of this research effort are measured through quantitative statistical analysis of the changes in second-year STEM undergraduate student retention rates and representation rates of women, Hispanics, and African American STEM majors.Item A Combined Gene Expression and Functional Study Reveals the Crosstalk Between N-Myc and Differentiation-inducing MicroRNAs in Neuroblastoma Cells(Impact Journals, 2016-10) Zhao, Zhenze; Ma, Xiuye; Shelton, Spencer D.; Sung, Derek C.; Li, Monica; Hernandez, Daniel; Zhang, Maggie; Losiewicz, Michael D.; Chen, Yidong; Pertsemlidis, Alexander; Yu, Xiaojie; Liu, Yuanhang; Du, LiqinMYCN amplification is the most common genetic alteration in neuroblastoma and plays a critical role in neuroblastoma tumorigenesis. MYCN regulates neuroblastoma cell differentiation, which is one of the mechanisms underlying its oncogenic function. We recently identified a group of differentiation-inducing microRNAs. Given the demonstrated inter-regulation between MYCN and microRNAs, we speculated that MYCN and the differentiation-inducing microRNAs might form an interaction network to control the differentiation of neuroblastoma cells. In this study, we found that eight of the thirteen differentiation-inducing microRNAs, miR-506-3p, miR-124-3p, miR-449a, miR-34a-5p, miR-449b-5p, miR-103a-3p, miR-2110 and miR-34b-5p, inhibit N-Myc expression by either directly targeting the MYCN 3'UTR or through indirect regulations. Further investigation showed that both MYCN-dependent and MYCN-independent pathways play roles in mediating the differentiation-inducing function of miR-506-3p and miR-449a, two microRNAs that dramatically down-regulate MYCN expression. On the other hand, we found that N-Myc inhibits the expression of multiple differentiation-inducing microRNAs, suggesting that these miRNAs play a role in mediating the function of MYCN. In examining the published dataset collected from clinical neuroblastoma specimens, we found that expressions of two miRNAs, miR-137 and miR-2110, were significantly anti-correlated with MYCN mRNA levels, suggesting their interactions with MYCN play a clinically-relevant role in maintaining the MYCN and miRNA expression levels in neuroblastoma. Our findings altogether suggest that MYCN and differentiation-inducing miRNAs form an interaction network that play an important role in neuroblastoma tumorigenesis through regulating cell differentiation.Item A Crystalline Oxide Passivation on In0.53Ga0.47As (100)(American Institute of Physics Publishing, 2017-03) Qin, Xiaoye; Wang, Wei-E; Droopad, Ravi; Rodder, Mark S.; Wallace, Robert M.The passivation of In0.53Ga0.47As surfaces is highly desired for transistor performance. In this study, the feasibility of a crystalline oxide passivation on In0.53Ga0.47As (100) is demonstrated experimentally. The (3 x 1) and (3 x 2) crystalline oxide reconstructions are formed on the de-capped In0.53Ga0.47As (100) surfaces through the control of the surface oxidation states. By monitoring the evolution of chemical states and associated structures of the In0.53Ga0.47As (100) surfaces upon O2 and subsequent atomic hydrogen exposure, we find that the control of the Ga oxide states is critical to the formation of the crystalline oxide reconstructions. The stability of the crystalline oxide layers upon the atomic layer deposition of HfO2 is investigated as well. Furthermore, the capacitance voltage behavior of metal oxide semiconductor capacitors with an HfO2 dielectric layer reveals that the crystalline oxide reconstructions result in a decrease in the density of interface traps (D it) from ~1 x 10 13 cm-2 eV-1 to ~1 x 10 12 cm-2 eV-1 compared with the de-capped surface. The crystalline oxide passivation offers a platform to develop In0.53Ga0.47As devices with a low density of interface states.Item A Dataset for the Flood Vulnerability Assessment of the Upper Cross River Basin Using Morphometric Analysis(Elsevier, 2020-02) Ogarekpe, Nkpa; Obio, Ekpe; Tenebe, Imokhai; Emenike, PraiseGod; Nnaji, ChidozieThe on-site collection of data is not only time consuming, but expensive and perhaps near impossible in restive communities within the upper Cross River basin (UCRB). Therefore, the importance of this data cannot be overemphasized. This article presents a Digital Elevation Model (DEM), land use and land cover (LULC) map, soil map, geology map and climatic datasets which enhance the understanding of the physical characteristics of the upper Cross River basin using morphometric analysis. The use of the LULC map, soil map and the DEM in conjunction with the climatic data enhance the creation of the Hydrologic Response Units (HRUs) and the water balance modelling. The simulation of the water balance at the HRU level enables the routing of the runoff to the reaches of the sub-basins and then to the channels. The geology map provides confirmatory information to the morphometric analysis. The compound factor computed from all the derived morphometric parameters enhance the determination of the overall flood potential of the congruent sub-basins.Item A General Hypothesis of Species Diversity(The American Society of Naturalists, 1979-01) Huston, Michael A.Many explanations for diversity patterns have been proposed, and there have been several recent reviews of the subject (Pianka 1966, 1974; Ricklefs 1973; Pielou 1975). High diversity has been attributed both to intense competition which forces niche restriction (Dobzhansky 1950; MacArthur and Wilson 1967)and reduced competition resulting from predation (Paine 1966; Harper 1969; Janzen 1970; Connell 1975). Diversity has been positively correlated with productivity (Connell and Orias 1964; Pianka 1966; MacArthur 1969) and negatively correlated with productivity (Yount 1956; Margalef 1969). The question is far from settled. This paper develops an approach to the problem of species diversity based on the nonequilibrium interactions of competing populations. Under nonequilibrium conditions, differences in diversity are strongly influenced by variations in the rates of competitive displacement between communities, and such factors as relative competitive abilities, niche partitioning, etc., may not be particularly important. This approach deals primarily with the maintenance of diversity, as opposed to the generation of diversity. While most of the current diversity hypotheses have some relation to the evolutionary origin of diversity, this will not be emphasized here.Item A Harmine-derived Beta-carboline Displays Anti-cancer Effects in vitro by Targeting Protein Synthesis(Elsevier, 2017-06) De Carvalho, Annelise; Chu, Jennifer; Meinguet, Celine; Kiss, Robert; Vandenbussche, Guy; Masereel, Bernard; Wouters, Johan; Kornienko, Alexander; Pelletier, Jerry; Mathieu, VeroniqueGrowing evidence indicates that protein synthesis is deregulated in cancer onset and progression and targeting this process might be a selective way to combat cancers. While harmine is known to inhibit DYRK1A and intercalate into the DNA, tri-substitution was shown previously to modify its activity profile in favor of protein synthesis inhibition. In this study, we thus evaluated the optimized derivative CM16 in vitro anti-cancer effects unfolding its protein synthesis inhibition activity. Indeed, the growth inhibitory profile of CM16 in the NCI 60-cancer-cell-line-panel correlated with those of other compounds described as protein synthesis inhibitors. Accordingly, CM16 decreased in a time- and concentration-dependent manner the translation of neosynthesized proteins in vitro while it did not affect mRNA transcription. CM16 rapidly penetrated into the cell in the perinuclear region of the endoplasmic reticulum where it appears to target translation initiation as highlighted by ribosomal disorganization. More precisely, we found that the mRNA expression levels of the initiation factors EIF1AX, EIF3E and EIF3H differ when comparing resistant or sensitive cell models to CM16. Additionally, CM16 induced eIF2α phosphorylation. Those effects could explain, at least partly, the CM16 cytostatic anti-cancer effects observed in vitro while neither cell cycle arrest nor DNA intercalation could be demonstrated. Therefore, targeting protein synthesis initiation with CM16 could represent a new promising alternative to current cancer therapies due to the specific alterations of the translation machinery in cancer cells as recently evidenced with respect to EIF1AX and eIF3 complex, the potential targets identified in this present study.Item A Heuristic Storage Location Assignment Based on Frequent Itemset Classes to Improve Order Picking Operations(Multidisciplinary Digital Publishing Institute, 2021-02) Li, Yue; Mendez-Mediavilla, Francis A.; Temponi, Cecilia; Kim, Junwoo; Jimenez, JesusMost large distribution centers’ order picking processes are highly labor-intensive. Increasing the efficiency of order picking allows these facilities to move higher volumes of products. The application of data mining in distribution centers has the capability of generating efficiency improvements, mainly if these techniques are used to analyze the large amount of data generated by orders received by distribution centers and determine correlations in ordering patterns. This paper proposes a heuristic method to optimize the order picking distance based on frequent itemset grouping and nonuniform product weights. The proposed heuristic uses association rule mining (ARM) to create families of products based on the similarities between the stock keeping units (SKUs). SKUs with higher similarities are located near the rest of the members of the family. This heuristic is applied to a numerical case using data obtained from a real distribution center in the food retail industry. The experiment results show that data mining-driven developed layouts can reduce the traveling distance required to pick orders.Item A Hierarchical Bayesian Approach to Ecological Count Data: A Flexible Tool for Ecologists(Public Library of Science, 2011-11) Fordyce, James; Gompert, Zachariah; Forister, Matthew L.; Nice, Chris C.Many ecological studies use the analysis of count data to arrive at biologically meaningful inferences. Here, we introduce a hierarchical Bayesian approach to count data. This approach has the advantage over traditional approaches in that it directly estimates the parameters of interest at both the individual-level and population-level, appropriately models uncertainty, and allows for comparisons among models, including those that exceed the complexity of many traditional approaches, such as ANOVA or non-parametric analogs. As an example, we apply this method to oviposition preference data for butterflies in the genus Lycaeides. Using this method, we estimate the parameters that describe preference for each population, compare the preference hierarchies among populations, and explore various models that group populations that share the same preference hierarchy.Item A Meta-Model to Predict the Drag Coefficient of a Particle Translating in Viscoelastic Fluids: A Machine Learning Approach(Multidisciplinary Digital Publishing Institute, 2022-01) Faroughi, Salah; Roriz, Ana; Fernandes, CelioThis study presents a framework based on Machine Learning (ML) models to predict the drag coefficient of a spherical particle translating in viscoelastic fluids. For the purpose of training and testing the ML models, two datasets were generated using direct numerical simulations (DNSs) for the viscoelastic unbounded flow of Oldroyd-B (OB-set containing 12,120 data points) and Giesekus (GI-set containing 4950 data points) fluids past a spherical particle. The kinematic input features were selected to be Reynolds number, 0Item A Method for the Detection of Poorly-Formed or Misclassified Saccades: A case study using the GazeCom Dataset(2022-02) Friedman, Lee; Djanian, Shagen; Komogortsev, OlegThere are many automatic methods for the detection of eye movement types like fixation and saccades. Evaluating the accuracy of these methods can be a difficult and time-consuming process. We present a method to detect misclassified or poorly formed saccades\footnote{Throughout the manuscript, when we use the word ``misclassified'', we will be referring to both misclassified or poorly formed. saccades.}, regardless of how they were classified. We developed and tested our method on saccades from the very large and publicly available GazeCom dataset. We started out by creating a total of 9 metrics (velocity shape, velocity shape amplitude, position shape, position shape amplitude, flatness, entropy, kurtosis, skewness, and the Dip Test statistic of multimodality) which will be explained below. We applied these metrics to horizontal saccades of 20, 40 and 60 ms duration. For each duration, we performed a data reduction step with factor analysis to see how these 9 metrics were naturally grouped. For every duration, there were 2 factors, one which was dominated by our velocity shape metric and one which was dominated by our entropy metric. We determined that the entropy metric was the single most valuable metric for detecting misclassified saccades. We illustrate the types of saccades that our entropy metric indicates are misclassified. Link to Python Code https://github.com/sdjanian/sacanalysisItem A Non-Invasive Stress Assay Shows That Tadpole Populations Infected with Batrachochytrium dendrobatidis Have Elevated Corticosterone Levels(Public Library of Science, 2018-12) Gabor, Caitlin R.; Fisher, Matthew C.; Bosch, JaimeBatrachochytrium dendrobatidis (Bd) is a fungus that causes the disease chytridiomycosis and is associated with widespread amphibian declines. Populations vary in their susceptibility to Bd infections, and the virulence of the infecting lineage can also vary. Both of these factors may manifest as a differential physiological stress response. In addition, variation in disease susceptibility across amphibian populations may be influenced by immunosuppression caused by chronic stress imposed by environmental factors. Here, we use a non-invasive water-borne hormone technique to assess stress levels (corticosterone) of free-living tadpole populations that are infected by Bd. We found that corticosterone release rates were higher in infected populations of two species of tadpoles (Alytes obstetricans and A. muletensis) than in an uninfected population for both species. The relationship between corticosterone and the intensity of infection differed between species, with only the infected A. obstetricans population showing a significant positive correlation. The higher corticosterone release rates found in A. obstetricans may be an outcome of infection by a highly virulent lineage of Bd (BdGPL), whereas A. muletensis is infected with a less virulent lineage (BdCAPE). These results suggest that different lineages of Bd impose different levels of stress on the infected animals, and that this may influence survival. The next step is to determine whether higher corticosterone levels make individuals more susceptible to Bd or if Bd infections drive the higher corticosterone levels.Item A Novel Evaluation of Two Related, and Two Independent Algorithms for Eye Movement Classification during Reading(2018-01) Friedman, Lee; Rigas, Ioannis; Abdulin, Evgeny; Komogortsev, OlegThis repository contains classified eye-movement data from the submitted paper, "Novel Evaluation of Two Related, and Two Independent Algorithms for Eye Movement Classification during Reading" Lee Friedman, Ioannis Rigas, Evgeny Abdulin and Oleg V. Komogortsev The Department of Computer Science, Texas State University, San Marcos, Texas. As of 2/19/2018, the third revision is under review at Behavior Research Methods. There are 4 directories included, each with exactly 20 files. These are the 20 files that were evaluated with 4 scoring methods. ONH – These data were scored by the method described in [1]. MNH – These data were scored by the method presented in the manuscript. IRF – These data were scored by the method presented in [2]. EDF – These data were scored by the EyeLink Parser. File naming convention: Take, for example, this name: “S_1051_S1_TEX_Class_EyeLink.csv”. This is data from Subject number 1051, recording session 1, the TEX (poetry reading) task and it contains classification data scored by the EyeLink Parser. “S_1066_S2_TEX_Class_IRF.csv” is data from Subject number 1066, recording session 2, the TEX (poetry reading) task and it contains classification data scored by [2]. “S_1334_S2_TEX_Class_ONH.csv” is data from Subject number 1334, recording session 2, the TEX (poetry reading) task and it contains classification data scored by [1]. Files like “S_1282_S2_TEX_Class_MNH.csv” were scored by the method described in the manuscript. The first column of every dataset is a msec timestamp. Only the first 26,000 msec of each file were processed for the manuscript. The second column of every dataset is the horizontal (X) eye position signal in degrees of visual angle. In the case of the ONH and the MNH methods, these position signals were smoothed. See manuscript for details. The third column of every dataset is the vertical (Y) eye position signal in degrees of visual angle. In the case of the ONH and the MNH methods, these position signals were smoothed. See manuscript for details. The fourth column of every dataset is the radial velocity of the eye movement signals. Please see manuscript for details of this calculation for every dataset. The fifth column of each dataset is a classification code, where 1 = fixation, 2 = saccade, 3 = post-saccadic oscillation, 4 = noise or artifact, and 5 is unclassified. Note that the IRF coded data did not use an “unclassified” category. References: [1] M. Nystrom and K. Holmqvist, "An adaptive algorithm for fixation, saccade, and glissade detection in eyetracking data," Behav Res Methods, vol. 42, no. 1, pp. 188-204, Feb 2010. [2] R. Zemblys, D. C. Niehorster, O. Komogortsev, and K. Holmqvist, "Using machine learning to detect events in eye-tracking data," Behav Res Methods, Feb 23 2017.Item A Review of Game Theory Applications for Seaport Cooperation and Competition(Multidisciplinary Digital Publishing Institute, 2020-02) Pujats, Karlis; Golias, Mihalis; Konur, DincerIn the ever-changing maritime shipping industry, ports, and more specifically, container terminals, are always on the search for better policy and operational plan developments. As the maritime shipping sector changes, new areas of research emerge. In this paper, we present a review of recent game theory applications for seaport cooperation and competition, accompanied by summary review tables stating the study, the modeling technique used, the methodology and objective, and summary of the results of each study. In total, we have reviewed 33 studies that used game theory models that investigated seaport and container terminal competition and cooperation involving various stakeholders with dating publication years from 2008 to 2019. The paper concludes with a discussion and proposed future research directions. The purpose of the paper is to serve as a reference guide to recent game theory applications on seaport cooperation and competition that would allow a quick understanding of work done in the field.Item A Shared Decision-making Tool to Prevent Substance Abuse: Protocol for a Randomized Controlled Trial(JMIR Publications, 2018-01) Long, Ju; Yuan, Juntao Michael; Johnson, Ron KimBackground: Substance use disorder (SUD) affects over 20 million adults and costs over $700 billion annually in the United States. It is one the greatest health care challenges we face. Objective: This research project seeks to enhance the standard practice of Screening, Brief Intervention, and Referral to Treatment (SBIRT) through a mobile solution easily incorporated into primary care that will promote shared decision making and increase referral and adherence to specialty care through continued follow-up care. Methods: This research will conduct an Office of Management and Budget (OMB)–approved randomized controlled trial (RCT) in primary care and SUD specialty service providers. The RCT will recruit a total of 500 SUD patients. Recruited patients will be randomized into control and intervention arms. Both arms will take initial baseline and exit (30 days) surveys to evaluate self-reported substance use and specialty service utilization. The control arm patients will receive usual care. The intervention group patients will receive technology-enhanced SBIRT and a mobile follow-up program to track goals and substance use at home. The RCT tracks participants for 30 days after the primary care encounter. We will collect feedback from the patients during the 30 days and count the number of patients who use specialty care services in specialty care programs for tobacco, alcohol, and drug abuse (both from self-reporting and from the service providers). Results: RCT and data collection are underway. We expect to report the data results in 2018. Conclusions: We expect that significantly more intervention group patients will receive specialty SUD care within 30 days following the SBIRT encounter at the primary care clinic compared to the control group. We also expect that the intervention group patients will report a greater reduction in substance use and a greater drop in Drug Abuse Screening Test and Addition Severity Index scores within 30 days.Item A Simple Conservation Tool to Aid Restoration of Amphibians following High-Severity Wildfires: Use of PVC Pipes by Green Tree Frogs (Hyla cinerea) in Central Texas, USA(Multidisciplinary Digital Publishing Institute, 2021-12) Suriyamongkol, Thanchira; Forks, Kaitlyn; Villamizar Gomez, Andrea; Wang, Hsiao-Hsuan; Grant, William E.; Forstner, Michael R. J.; Mali, IvanaAmphibians are the most threatened vertebrate class based on the IUCN Red List. Their decline has been linked to anthropogenic activities, with wildfires being among the most conspicuous agents of habitat alterations affecting native amphibians. In 2011, the most destructive wildfire in Texas history occurred in the Lost Pines ecoregion of central Texas, USA, burning 39% of the 34,400 ha forest and drastically decreasing available habitats for many native wildlife species, including the green tree frog (Hyla cinerea). We investigated use of PVC pipes as artificial refuges for green tree frogs in different habitats within this post-fire pine forest. We monitored green tree frog use of small (diameter 38.1-mm, 1.5 inch) and large (diameter 50.8-mm, 2 inch) pipes located adjacent to, and 5 m from, ponds in burned and unburned areas over a 5-month period. We caught 227 frogs, 101 (24 adults and 77 juveniles) in burned and 126 (61 adults, 63 juveniles, and 2 unknown) in unburned areas. A relationship between pipe use by adults and/or juveniles and pipe location in burned versus unburned areas was found, but pipe use by adults and/or juveniles and pipe size were independent. Pipe use by adults and/or juveniles and pipe size were also independent. Juveniles were more frequently observed in pipes located adjacent to ponds. Our results confirmed that PVC pipes merit consideration as a simple, inexpensive, conservation tool to aid in restoration of green tree frog populations after high-severity wildfires. Such artificial refuges may be particularly important for survival of juveniles in severely altered post-fire habitats.Item A Three Year Study of Metal Levels in Skin Biopsies of Whales in the Gulf of Mexico after the Deepwater Horizon Oil Crisis(Elsevier, 2018-02) Wise, John Pierce, Jr.; Wise, James T. F.; Wise, Catherine F.; Wise, Sandra S.; Gianios, Christy, Jr.; Xie, Hong; Walter, Ronald B.; Boswell, Mikki; Zhu, Cairong; Zheng, Tongzhang; Perkins, Christopher; Wise, John Pierce, Sr.In response to the explosion of the Deepwater Horizon and the massive release of oil that followed, we conducted three annual research voyages to investigate how the oil spill would impact the marine offshore environment. Most investigations into the ecological and toxicological impacts of the Deepwater Horizon Oil crisis have mainly focused on the fate of the oil and dispersants, but few have considered the release of metals into the environment. From studies of previous oil spills, other marine oil industries, and analyses of oil compositions, it is evident that metals are frequently encountered. Several metals have been reported in the MC252 oil from the Deepwater Horizon oil spill, including the nonessential metals aluminum, arsenic, chromium, nickel, and lead; genotoxic metals, such as these are able to damage DNA and can bioaccumulate in organisms resulting in persistent exposure. In the Gulf of Mexico, whales are the apex species; hence we collected skin biopsies from sperm whales (Physeter macrocephalus), short-finned pilot whales (Globicephala macrorhynchus), and Bryde's whales (Balaenoptera edeni). The results from our three-year study of monitoring metal levels in whale skin show (1) genotoxic metals at concentrations higher than global averages previously reported and (2) patterns for MC252-relevant metal concentrations decreasing with time from the oil spill.Item Abe Lincoln and the Leonids(Sky Publishing Corp., 1999-11) Jasinski, Laurie E.; Olson, Donald W.No abstract prepared.Item Accelerated Development in Johnsongrass Seedlings (Sorghum halepense) Suppresses the Growth of Native Grasses through Size-Asymmetric Competition(Public Library of Science, 2017-05) Schwinning, Susanne; Meckel, Heather; Reichmann, Lara G.; Polley, H. Wayne; Fay, PhilipInvasive plant species often dominate native species in competition, augmenting other potential advantages such as release from natural enemies. Resource pre-emption may be a particularly important mechanism for establishing dominance over competitors of the same functional type. We hypothesized that competitive success of an exotic grass against native grasses is mediated by establishing an early size advantage. We tested this prediction among four perennial C4 warm-season grasses: the exotic weed Johnsongrass (Sorghum halepense), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparius) and switchgrass (Panicum virgatum). We predicted that a) the competitive effect of Johnsongrass on target species would be proportional to their initial biomass difference, b) competitive effect and response would be negatively correlated and c) soil fertility would have little effect on competitive relationships. In a greenhouse, plants of the four species were grown from seed either alone or with one Johnsongrass neighbor at two fertilizer levels and periodically harvested. The first two hypotheses were supported: The seedling biomass of single plants at first harvest (50 days after seeding) ranked the same way as the competitive effect of Johnsongrass on target species: Johnsongrass < big bluestem < little bluestem/switchgrass, while Johnsongrass responded more strongly to competition from Johnsongrass than from native species. At final harvest, native plants growing with Johnsongrass attained between 2-5% of their single-plant non-root biomass, while Johnsongrass growing with native species attained 89% of single-plant non-root biomass. Fertilization enhanced Johnsongrass' competitive effects on native species, but added little to the already severe competitive suppression. Accelerated early growth of Johnsongrass seedlings relative to native seedlings appeared to enable subsequent resource pre-emption. Size-asymmetric competition and resource-pre-emption may be a critical mechanism by which exotic invasive species displace functionally similar native species and alter the functional dynamics of native communities.Item Acoustic Properties of Innovative Concretes: A Review(Multidisciplinary Digital Publishing Institute, 2021-01) Fediuk, Roman; Amran, Mugahed; Vatin, Nikolai; Vasilev, Yuriy; Lesovik, Valery; Ozbakkaloglu, TogayConcrete is the most common building material; therefore, when designing structures, it is obligatory to consider all structural parameters and design characteristics such as acoustic properties. In particular, this is to ensure comfortable living conditions for people in residential premises, including acoustic comfort. Different types of concrete behave differently as a sound conductor; especially dense mixtures are superior sound reflectors, and light ones are sound absorbers. It is found that the level of sound reflection in modified concrete is highly dependent on the type of aggregates, size and distribution of pores, and changes in concrete mix design constituents. The sound absorption of acoustic insulation concrete (AIC) can be improved by forming open pores in concrete matrices by either using a porous aggregate or foam agent. To this end, this article reviews the noise and sound transmission in buildings, types of acoustic insulating materials, and the AIC properties. This literature study also provides a critical review on the type of concretes, the acoustic insulation of buildings and their components, the assessment of sound insulation of structures, as well as synopsizes the research development trends to generate comprehensive insights into the potential applications of AIC as applicable material to mitigate noise pollution for increase productivity, health, and well-being.