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3D models of glioblastoma interaction with cortical cells
No full textIntroduction: Glioblastoma (GBM) invasiveness and ability to infiltrate deep into the brain tissue is a major reason for the poor patient prognosis for this type of brain cancer. Behavior of glioblastoma cells, including their motility, and expression of invasion-promoting genes such as matrix metalloprotease-2 (MMP2), are strongly influenced by normal cells found in the brain parenchyma. Cells such as neurons may also be influenced by the tumor, as many glioblastoma patients develop epilepsy. In vitro models of glioblastoma invasiveness are used to supplement animal models in a search for better treatments, and need to combine capability for high-throughput experiments with capturing bidirectional interactions between GBM and brain cells.Methods: In this work, two 3D in vitro models of GBM-cortical interactions were investigated. A matrix-free model was created by co-culturing GBM and cortical spheroids, and a matrix-based model was created by embedding cortical cells and a GBM spheroid in Matrigel.Results: Rapid GBM invasion occurred in the matrix-based model, and was enhanced by the presence of cortical cells. Little invasion occurred in the matrix-free model. In both types of models, presence of GBM cells resulted in a significant increase in paroxysmal neuronal activity.Discussion: Matrix-based model may be better suited for studying GBM invasion in an environment that includes cortical cells, while matrix-free model may be useful in investigation of tumor-associated epilepsy.</jats:p
From basalt to biosphere: Early non-vent community succession on the erupting Vailulu’u deep seamount
No full textVolcanic eruptions provide rare opportunities to witness the biological recolonization of areas covered by new lava flows by effectively resetting the ecological succession clock to zero. The role of submarine volcanic eruptions as disturbance events and the resulting patterns of ecological succession have mainly been studied in hydrothermal vent ecosystems. However, the effects of submarine volcanic eruptions as disturbance forces have rarely been studied in non-vent ecosystems, particularly on seamounts. Here, we document the early stages of ecological succession of non-vent benthic communities inhabiting the summit caldera of the active Vailulu’u submarine volcano in American Samoa. Sitting above the Samoan volcanic hotspot, Vailulu’u is the youngest volcano of the Samoan chain. Repeated mapping of Vailulu’u in 1999, 2005, 2006, 2012, and 2017 revealed the progressive growth of a new cone named Nafanua. In 18 years, the cone grew &gt;300 meters in height from a starting depth of ~1000 meters below sea level (mbsl). The differential analyses of this time-series bathymetry dataset enabled the assignment of maximum age ranges to different portions of the new cone. High-definition ROV imagery collected in 2017 revealed patterns of community structuring consistent with ecological succession: newly erupted seafloor contained a subset of the benthic species found on older seafloor. Furthermore, individual animal sizes in the younger seafloor zones were smaller than in the older zones. This unusual interdisciplinary combination of geological and biological observations provides constraints on which deep-sea animals recolonize new seafloor after a major disturbance event and how quickly. This knowledge could be applied to identify signs and states of recovery from anthropogenic disturbances by a deep seamount ecosystem.</jats:p
The Influence of Nominal Composition on the Solidification Behavior, Tensile Properties, and Weldability of Cast Monel Alloys
No full textCast Monel alloys are used in many industrial applications requiring a combination of good mechanical properties and excellent resistance to corrosion. These alloys are most often used in the as-cast condition and thus have properties that are highly dependent on the nominal composition, solidification behavior, and cast microstructure. Despite relative widespread use, many of the fundamental composition-structure-property relationships in this alloy system are not well understood. In this work, a matrix of 11 alloys with controlled variations in solute concentrations were characterized via scanning electron microscopy, x-ray diffraction, electron probe microanalysis, differential scanning calorimetry, uniaxial tensile testing, and longitudinal Varestraint testing to evaluate the effects of composition on the solidification behavior, microstructure, tensile properties, and solidification cracking susceptibility in cast Monel alloys.It was found that increasing Nb concentration in the presence of the high-C content stabilized primary NbC and suppressed graphite formation during solidification. Increasing nominal concentration of Si, and its segregation to the liquid phase during solidification, was found to promote terminal ?/Ni31Si12 eutectic reactions and ?1 precipitation within the matrix during cooling from casting. Using experimental data, an austenite (Ni ,Cu, Fe, Mn, Nb, C) - Si pseudo-binary solidification diagram was created to describe the solidification path and microstructure of cast Monel alloys. The diagram was also applied to create a quantitative model to predict the ?/Ni31Si12 eutectic fraction as a function of nominal composition. Increases in the concentration of other solute elements such as Cu and Mn were shown to reduce the solubility limit of Si within austenite and promote increased silicide formation via eutectic and solid-state precipitation reactions.The increase in ?1 precipitation induced by higher Si concentrations was shown to significantly increase yield strength and tensile strength, while changes to the Nb concentration were found to have no discernible effects. Elevating Cu concentration from 30 wt.% up to 45 wt.% significantly improved strengthening, while a further increase to 60 wt.% Cu was found to weaken the alloys. The addition of 0.5 wt.% V was found to be effective at increasing yield strength and tensile strength in alloys containing 3 wt.% Si. Fractography revealed that the presence of hard secondary phases such as NbC and silicide eutectic constituents acted as crack initiation and propagation sites during loading, which caused significant reductions in tensile ductility and promoted quasi- cleavage failure.Low-Si Monel alloys were found to have fairly good resistance to solidification cracking, however, increases in Si concentration and other solute elements that promoted g/silicide eutectic reactions significantly increased the cracking susceptibility. Modelling work showed that this was a result of residual liquid stabilized to relatively low temperatures in the final stages of solidification which prevented dendrite coalescence and left the alloy vulnerable to solidification cracking. The findings of this work provide significant contributions to the understanding of Monel alloy solidification behavior, and help elucidate how composition can be controlled to engineer microstructures and resulting properties
Co-Evolution in Complex Adaptive Water Systems from Long-Term Planning to Short-Term Responses
No full textWater system planning and management is the science between the natural environment and human society. This dissertation explores the coevolution in complex adaptive water systems from long-term planning to short-term responses to advance our understanding of interactions between natural and human systems using computational modeling approaches. This dissertation investigates the effect of the social norm on farmers\u27 water diversion behaviors interacting with the hydrological environment through a two-way coupling model. Coupled models bidirectionally bridge the information flow between RiverWare, a commonly adopted water planning model, and an agent-based model (ABM), a human model constructed from a bottom-up modeling logic. ABM can capture the heterogeneity of human actors (farmers) and reveal the emergence of collective patterns. The coupled models are applied to show how the changing water allocation policy impact agents\u27 characteristics (e.g., risk attitudes). To further explore the coupled models\u27 characteristics, an open-source Python package, Hydrological model for Coupled Natural-Human Systems, is developed to facilitate the complex adaptive water systems (CAWS) modeling process and conduct an uncertainty analysis. This dissertation analyzes how the model output uncertainty in nature and human systems vary with different ABM complexities concerning uncertainty sources like climate change scenarios uncertainty, internal climate variability, and different model configurations with parameter sets or model structures that are equally capable of producing similar outcomes using the law of total variance. The last research topic shifts the focus from long-term planning to short-term responses. Those responses are viewed as the drivers accumulating to form the trend of long-term changes. This dissertation quantifies the compounding risks of flood caused by storms and cyber-physical attacks in a smart stormwater system, a pond-conduit network that has water level sensors and outflow gate actuators to be remotely controlled by a real-time control system modeled by a linear quadratic Gaussian controller. The numerical experiments illustrate how the maliciously injected data impact the system operation and the pattern of flooding risks in the urban area. The results serve as an initial step to discussing the potential human responses toward compounding risks that might trigger the long-term evolution of CAWS. In sum, this dissertation contributes to advancing the understanding of coevolution in CAWS and encourages future work to develop a holistic framework linking the perspectives of long-term planning and short-term responses in CAWS modeling
Future (2020-2099) Carbon and Water Dynamics of Lehigh and Northampton Counties Based on Land Use and Land Cover Changes
No full textIncreased urbanization has reduced the amount of green space (i.e., vegetated area) within urban areas and is projected to continue doing so into the future. Less greenspace will mean reduced carbon sink potential across the urban landscape. Through the use of biogeochemical modeling, different land use scenarios can be developed and run for the future (2020-2099) to compare and quantify the potential for change in carbon and water dynamics by having more tree cover and reducing impervious surfaces or turf lawns. This study uses the Lehigh Valley, PA as a case study. To examine the effect of land use and land cover (LULC) on carbon storage, the Terrestrial Ecosystem Model (TEM) was used to run future scenarios with land use and land cover changes (LULCC). Current ratios between impervious surfaces, forests, barren fields, and turflawn were developed from Landsat 8 data. Future changes in land use were implemented to simulate an increase or decrease in forested areas over preexisting impervious surface or turflawn to determine the carbon and water impact of these changes. These changes were based on policy suggestions in the recent Bethlehem Climate Action Plan (CAP, 2021), with a particular attention adding greenspace to vulnerable frontline communities. Future climate data are from the NCAR (National Center for Academic Research) CESM (Community Earth System Model) model with the RCP8.5 (Representative Concentration Pathways) scenario as downscaled and bias-corrected by MACA (Multivariate Adaptive Constructed Analogs). These results show that the effect of deforestation is larger than the effect of reforestation. Due to young stand-age trees having a lower capacity for carbon storage than mature trees, the loss of the mature trees has a more immediate impact. A 25% change of impervious surface to forest resulted in statistically insignificant increases in carbon stocks and fluxes for 2070-2099. In contrast, when converting 25% of forest area to impervious surface, the decrease in vegetation carbon is -24.6%, Net Primary Productivity (NPP) is -19.8%, and Net Carbon Exchange (NCE) is -31.6% for the same time period. More than 10% change is required in most cases to get a significant effect. One exception is that even though only 4% of the total area of the region was changed when converting 50% of the lawn to forest, the vegetation carbon, and cumulative NCE both increased significantly, and soil carbon decreased. The 10% conversion from forest to lawn and forest to impervious surface only changed the total area of the region by 6% and produced statistically significant changes as well. The study shows that within the city of Bethlehem, the most socially vulnerable area benefits the most from increasing the number of trees. When converting 25% of the impervious area to forest, South Bethlehem increased its vegetation carbon by 38%, NPP by 16%, and NCE by 252%. The results from increased tree cover are more carbon storage, more water stored in soil, and generally safer and cleaner environments for their residents
Is China\u27s One Belt One Road the Death of Western Imperialism
No full textChina\u27s bold restructuring of global trade labeled the One Belt One Road initiative seeks to radically transform the economic and logistical power structure of the world. With hundreds of billions of dollars invested into infrastructure based on trade in countries spanning Southern Asia, the Middle East, and the continent of Africa, the OBOR may be one of the most ambitious government projects ever. While the One Belt One Road is often celebrated as a revitalization of global trade meant to match the historic Silk Road, many have raised criticisms of the initiative. Some scholars and activists claim the project is an imperialistic endeavor meant to gather soft power to control foreign trade, and resources subjecting them to Beijing\u27s will. Here I explore the foundational texts regarding imperialism, notably Hobson, Lenin, and Nkrumah to analyze the One Belt One Road\u27s developments throughout Africa and determine its imperialistic intent. Noting the colonial history of Africa from the Berlin Conference of 1884 to compare the current relationship between China and Africa of today, to that of the past. This exploration further implicates the imperialistic actions of China, while also acknowledging the downfall of older versions of imperialism in Africa
Phoneme Similarity in English and Mandarin Chinese Language Production
No full textDespite general agreement on the main stages of language production, the stage of phonetic encoding and articulation remains understudied. To shed light on this neglected component, more specifically the interaction of phonological units and articulatory features, this thesis studied the effects of initial phoneme similarity in controlled word-pair production experiments. I comprehensively examined the cost of different feature type differences in word onsets in parallel English and Mandarin Chinese word pair production experiments while also varying phonological contexts (presence or absence of shared rhyme segments). Monosyllabic word pairs were produced using a cued word-order procedure that requires the generation of phonology immediately before speaking. I predicted phoneme similarity costs for all features in both languages. The rhymed context should have more cost than the unrhymed context but keep the same pattern across features. Competition indexed by slower speech initiation latencies and increased errors was present in both rhymed (e.g., birch-perch, ?(bi3)-?(pi2)) and unrhymed (e.g., bog-pouch ?(bu4)-?(pa4)) related conditions in both languages. Surprisingly, for unrhymed word pairs, place was the most influential feature in both languages. For rhymed word pairs, all features were important, place remained the most robust effect in Chinese, but voice was the strongest feature in English. Error patterns were broadly consistent with the response time data. I conclude that the phoneme similarity effect operates both in a syllable-centric (Chinese) as well as a phoneme-centric (English) phonological system, suggesting a limited role for earlier production stages
Optical Trapping of Li-6 for Studies of Transport in Strongly Interacting Fermions
No full textUltracold gases provide a clean setup for investigating the many-body physics of stronglyinteracting fermions. Due to the universal nature of strongly interacting fermionic systems, an ultracold gas can serve as a quantum simulator for other strongly interacting systems of fermions such as neutron stars and high-Tc superconductors [1] [2]. A better understanding of such systems could potentially have great scientific and technological implications. In this thesis, I describe the construction of an apparatus that can be used for future experiments on ultracold atoms probing questions related to spin and heat transport in a strongly interacting gas of 6Li atoms. Multiple stages of cooling have been successfully completed on the way towards establishing a quantum degenerate ultracold gas of Li-6. To this end a magneto-optical trap (MOT) has been realized with a temperature on the order of ? 1mK, a compressed MOT (cMOT) has been realized with a temperature ? 600?K, and most recently a crossed optical-dipole trap (ODT) with a temperature ? 70?K. The foundations have also been laid for the final stage of atomic trapping in our apparatus, the multi-region trap, or "box trap"; in particular I will describe an optical setup that has been tested and is suitable for use in creating the hollow cylindrical walls or our box trap, which we like to call the "ring beam"
Individualized Education Programs for Students in Juvenile Justice Facilities: A Mixed Methods Content Analysis
No full textThe Individuals with Disabilities Education Act (2004) entitles students who qualify for special education services to a free and appropriate education (FAPE) across all public education settings, including juvenile justice (JJ) facilities. JJ facilities have disproportionately higher rates of students with disabilities, who tend to experience difficulties in academics and social development (Bullis et al., 2002; Quinn et al., 2005; U.S. Department of Education, 2009). This study describes a mixed methods content analysis of IEP documents for students with disabilities (N=22) served in a Pennsylvania JJ facility. Specifically, this study sought to investigate (a) the specific needs outlined in the IEPs for student with disabilities served in the JJ setting; (b) the alignment between present level of academic and functional performance (PLAAFP), annual goals, specially designed instruction, and related services; and (c) whether the IEPs meet federally set substantive requirements to address student needs and promote meaningful growth toward goals. Overall, findings indicate that the sample IEPs fail to meet federal substantive requirements across several factors, including: a) sufficient assessment and documentation of student PLAAFP, b) goal ambition and clarity, and c) behavior/mental health services. Furthermore, analyses suggest potential misalignment between the IEPs\u27 stated needs and provided services, particularly in the area of behavior and mental health. Implications of the findings and recommendations for research and practice are outlined in the discussion
Rheological Characterization Of Colloidal Gels During Phase Transitions Using Multiple Particle Tracking Microrheology
No full textCharacterizing rheological properties and structural changes of colloidal materials during sol-gel transitions is critical for product design using these materials as a rheological modi- fier. This thesis focuses on the characterization of colloidal rod materials. These materials are chosen because the anisotropy of a colloidal rod enables the modification of rheology with small amounts of material. In this work, three types of colloidal rod systems are in- vestigated, hydrogenated castor oil (HCO), polyamide (PA), and microfibrillated cellulose (MFC). Multiple particle tracking microrheology (MPT) and bulk rheology are used to char- acterize colloidal rod system phase transitions. MPT is a passive microrheology technique that measures the Brownian motion of fluorescent probe particles embedded in the material and relates this motion to material rheological properties. Time-cure superposition (TCS) can be used to analyze MPT data to determine critical values at the phase transition, which identifies the structure of the material. TCS can provide critical information on material properties during its phase transition. This is essential to determine whether the materials suit the desired end-use.We first characterize the gelation of both HCO and PA with different surfactant con- centrations. HCO and PA have similar colloidal dimensions, but HCO is a polydisperse colloidal system, and PA is a monodisperse colloidal system. This work aims to character- ize the effect of surfactant concentration and polydispersity of the colloidal system on the gelation evolution. We use depletion interactions to drive the gelation of both HCO and PA. MPT is used to characterize gelation. From TCS analysis, the critical relaxation exponents, nsurfactant:colloid=16 and nsurfactant:colloid>16, are calculated for gelation of both HCO and PA at a concentration of surfactant : colloid = 16 and surfactant : colloid > 16, respectively.The values of nsurfactant:colloid=16 and nsurfactant:colloid>16 are different indicating a change in the microstructure at the phase transition caused by different amounts of surfactant in the system. At surfactant : colloid = 16, the system is a tightly associated network. The same colloidal system is a loosely associated networks at surfactant : colloid > 16. Using zeta potential and differential dynamic microscopy measurements, we determine that this variation in the value of n is caused by a change in the electrostatic forces between colloidal rods caused by a change in surfactant concentration. At surfactant : colloid = 16, col- loidal rods are stable and repel each other strongly. This system is a suspension of single colloidal rods prior to gelation. At surfactant : colloid > 16, electrostatic forces between the colloidal rods are weaker, causing clusters or bundles of colloidal rods to form in the system prior to gelation. This difference in the structure of the material suspension leads to a change in the n value at the phase transition. Comparing the results between HCO and PA, there is no dependence on the change in the structural and rheological properties be- tween these two systems. This suggests that the difference in polydispersity between HCO and PA does not impact their structure and rheological properties at the sol-gel transition.Next, phase diagrams are built for both HCO and PA over a large parameter space at different compositions by systematically changing the concentration of the colloid, surfac- tant and depletant using MPT and bulk rheology. The effect of each component is first measured with MPT. For both HCO and PA, increasing the colloid concentration from 0.2 to 0.8 wt% does not lead to any phase change in the system. Increasing the deple- tant concentration induces phase transitions in both systems at any combination of colloid and surfactant concentration. Changing the concentration of surfactant can induce phase transitions when the depletant concentration is near the critical depletant concentration (minimum required amount of depletant to induce gelation). For the phase diagram cre- ated with bulk rheological measurements for both HCO and PA, the elasticity of the system increase as colloids concentration increases. The elasticity of both systems remains constant as depletant and surfactant concentration is changed. Comparing measurements by MPT and bulk rheology, different trends are measured when the concentration of each component is varied. This is because of the different measurement regimes and methods in these two different measurements.Finally, the phase transition of MFC, a renewable colloidal rod, is also characterized. In this work, the surface of MFC is oxidized (OMFC) to enable the material to be gelled using either an anionic or cationic surfactant. We use an extension of MPT, bi-disperse MPT, to measure the change in the microstructure and rheological properties of OMFC at different length scales simultaneously during gelation. We determine that the gelation evolution of OMFC is dependent on the charge of the surfactant. OMFC gelation in anionic surfactant is a gradual process. Conversely, OMFC gelation in cationic surfactant is a rapid process followed by structural rearrangement. TCS indicates that the structure at the phase transition point is dependent on colloid concentration. At high colloid concentration, the system is a tightly associated structure at the gel point. The system is a loosely associated structure at the gel point at low colloid concentration. Using bi-disperse MPT, we measured that the structure of the material is length scale dependent. The value of n depends on the size of the particle when gelation in an anionic surfactant is measured. The rearrangement after gelation in cationic surfactant is also largely dependent on the size for the gel in cationic surfactant. In this work, we also use bulk rheology to characterize OMFC gelation in both types of surfactant. From bulk rheology, we measure that OMFC gelled in cationic surfactant is stiffer, but yields at a lower stress than OMFC gelled in anionic surfactant.Overall, this work presents the characterization of colloidal rod materials during their sol-gel transitions. The information gained in this work can be used to enable desired rheological properties to be designed into formulations using these colloidal rod systems as rheological modifiers, providing a guide for product design