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Underexplored Aspects of Host Finding and Host Acceptance in Parasitoid Wasps
No full textParasitoids use sensory cues, such as olfactory infochemicals, that can be emitted directly by their potential herbivore hosts or plants as a damage response to herbivory to locate potential hosts for oviposition. Despite intensive studies on interactions between parasitoids and their host, certain aspects of chemical communication of the interaction still need to be explored. This study aimed to study the different understudied aspects of odor-mediated host finding and acceptance response of two parasitic wasps (Hymenoptera: Braconidae) with varying degrees of host specificity, Microplitis croceipes (Cresson) (specialist) and Cotesia marginiventris (Cresson) (generalist), integrating multiple tools (analytical, behavioral, electrophysiological). These aspects include the use of plant volatile to determine the parasitism status of damaging hosts, parasitoid���s use of host cuticular composition as cues for host acceptance, and the influence of associative learning of host-related odor in the odor-mediated flight behavior of specialist parasitoids.
The existing literature on the chemical ecology of host selection behavior of parasitoid wasps was discussed, the understudied aspects were identified, and a rationale for the study was provided. Behavioral bioassays were conducted to test the ability of specialist M. croceipes to utilize plant volatiles as host-discrimination cues and found that parasitoids can discriminate and show a preference for volatiles from plants infested by unparasitized hosts over volatiles from plants infested by parasitized hosts and was mediated by the alteration in plant volatile emission due to infestation by parasitized hosts. Behavioral and electrophysiological studies were performed to evaluate the role of host cuticular composition in mediating host recognition and acceptance behavior of M. croceipes and C. marginiventris and reported that specialist parasitoids are more dependent on host-specific kairomonal cues than generalist during host acceptance. The effect of associative learning on the odor-mediated flight behavior of M. croceipes was evaluated by performing a wind tunnel bioassay using two host-related compounds, ��-pinene, and ��-farnesene, and found that odor learning results in enhanced and directed upwind flight towards the learned odors. Results from this dissertation have contributed to our understanding of the understudied but essential aspects of semiochemical-mediated behavior and foraging strategies employed by parasitoids during odor-mediated host findings
Combustion Solutions for Reduced Methane Emissions from Large Bore Natural Gas Engines
No full textLegacy large bore, natural gas two-stroke engines form a vital component of the pipeline industry, but with increasing stringent pushes to reduce emissions, the necessity of improving performance of an ageing engine fleet grows more critical than ever. Precombustion chambers are frequently implemented on these engines to improve ignition stability and extend the lean limit of operation, a process which brings an additional benefit of reducing harmful emissions such as oxides of nitrogen (NOx) and hydrocarbons (HC). While prechambers reduce the carbon footprint from pipeline compressor stations, the pathway to zero emissions of the future still contains a plethora of research avenues to explore.
This study sought to explore two potential combustion solutions for reducing methane emissions from large bore natural gas engines. First, the Cooper-Bessemer GMV4 engine was fully simulated using Converge CFD and validated using experimental data. Before igniting the primary prechamber, radical and intermediate species were seeded throughout the main combustion chamber by use of a second, deliberately quenched prechamber. This served to boost reactivity and promote flame propagation throughout unburned regions of the chamber. Multiple temperature levels, injection timings, and chemical species compositions were investigated, for which each was then examined for early ignition limits, surviving concentration of seeded species, and overall impact on residual methane and the combustion process.
Second, the Cooper Ajax E-565 engine in open-chambered configuration was fully simulated using Converge CFD software and validated using experimental data. The open-chambered configuration was then modified to a prechambered configuration, and input parameters, such as fuel delivery and spark timing, were adjusted using best real-world design practices. This model was then used as a foundation upon which to evaluate the sensitivity of in-cylinder mixing between prechamber and main chamber gases to changes in intake manifold and port design. Eight different manifolds designs were created and analyzed for overall air flow, mixing quality, and general combustion performance. The results were then examined for an extensive investigation of factors preventing oxidation of residual methane as well as the production mechanisms of NOx emissions
Development of a Finite Element Analysis (FEA) Model for Predicting Elbow Torque of the Apollo A7LB Extravehicular Activity (EVA) Spacesuit Pressurized Sleeve
No full textEVA spacesuits are critical to human survivability in the hostile environment of space, which consists of low atmospheric pressures (e.g., vacuum in LEO and on the lunar surface) and temperature extremes (e.g., ���65��C to 125��C in LEO). While spacesuits must protect humans against these conditions, maintaining an astronaut���s mobility is also crucial to achieve mission objectives such as in a return to the Moon as defined by the Artemis architectures. Spacesuit mobility is largely driven by the design of joints such as in the knees, shoulders, ankles, waist, and elbows. In the Apollo A7L/A7LB spacesuits, full circumferential rubber-dipped nylon convolutes were utilized in these joint locations. Understanding the Apollo elbow joint design���s mobility, in comparison to the Extravehicular Mobility Unit���s (EMU) flat pattern gore design, could provide new insights for the development of future spacesuits. In this research, an Abaqus FEA model was developed to predict elbow joint torques during pressurized bends using the A7L/A7LB pressure garment assembly arm configuration. The model was scripted to allow for simple adjustment of numerous design variables, such as the number and size of the convolutes. Through DOE studies, it was found that sleeve radius had the largest proportional effect on joint torque, while sleeve thickness and fabric bias direction Young���s modulus had smaller effects. Increasing number of convolutes reduced joint torque, but this effect diminished at larger numbers. Increasing operating pressure significantly increased joint torque, especially at high bend angles (such as 120 degrees). The results showed that lowest torque designs from these DOE studies required less joint torque than an Aerospace Human Systems Laboratory (AHSL) EMU FEA elbow model up to 55-60 degrees, and after 105 degrees. The model was also adjusted to available Apollo sleeve dimensions, and the material properties were approximated to yield joint torque data closely aligned with an A7LB empirical measurement in literature. Results showed this Apollo sleeve required less joint torque than the AHSL EMU model from 0-40 degrees. Lastly, the model was adjusted to an alternative convolute joint used in empirical joint testing, and joint torque results were the same order of magnitude as reported data
John Bickham field notebook: AK16001-AK16500.pdf
No full textBound book, each page corresponds to a karyotype slide data.Data pages for AK16501-AK17000 corresponding to unique identifiers of specimens/samples examined for biological research. Specimens are primarily housed at Texas A&M University; Biodiverstiy Research and Teaching Collection
Integrated Protein Turnover: Toward a New Understanding of Cellular Protein Metabolism
No full textProtein metabolism lies at the heart of cellular health. However, the intersections between protein anabolism and catabolism are not completely understood. Here we propose a new view on cellular protein metabolism, the integrated protein turnover model, which we argue better explains the events and evidence underlying anabolic and catabolic states in cells. Instead of viewing protein synthesis and breakdown as separate pathways, we argue that these processes are fundamentally and inextricably linked, and that overall anabolism and catabolism are the result of simultaneous and coordinated action of all the protein metabolic machinery, encompassing the mTOR, autophagic, and ubiquitin-proteasome pathways. We provide the first direct evidence that autophagy is required for protein synthesis in muscle, such that mTORC1-mediated anabolism cannot occur without input from the autophagic pathway. We further show that expression of a select autophagy gene, ATG4B is high in lung and pancreatic cancers and its expression is associated with mortality. Inhibiting ATG4B suppresses cancer cell growth and protein synthesis, allowing for targeting of both autophagic and anabolic markers of metabolism. Finally, we demonstrate that microRNA are a viable candidate for the regulation of the overall proteostatic network, and that removing select microRNA (mir15a/16) from skeletal muscle activates muscle anabolic signaling, while restoring these same microRNA slows anabolism and growth in cancer. Our results demonstrate the strength of the integrated protein turnover model, and indicate new avenues for both the understanding and targeting of protein metabolism in health and disease
Reinforcement Learning Model to Demystify the Limited Human Motor Learning Efficacy Due to the Sensory Mismatch
No full textVision and proprioception have fundamental sensory mismatches in delivering locational information, and such mismatches are critical factors limiting the efficacy of motor learning. However, it is still not clear how and to what extent this mismatch limits motor learning outcomes. To further the understanding of the effect of sensory mismatch on motor learning outcomes, a reinforcement learning algorithm and the simplified biomechanical elbow joint model were employed to mimic the motor learning process in a computational environment. By applying a reinforcement learning algorithm to the motor learning of elbow joint flexion task, simulation results successfully explained how visual-proprioceptive mismatch limits motor learning outcomes in terms of motor control accuracy and task completion speed. The larger the perceived angular offset between the two sensory modalities, the lower the motor control accuracy. Also, the more similar the peak reward amplitude of the two sensory modalities, the lower the motor control accuracy. In addition, simulation results suggest that insufficient exploration rate limits task completion speed, and excessive exploration rate limits motor control accuracy. Such a speed-accuracy trade-off shows that a moderate exploration rate could serve as another important factor in motor learning
Developing a Multiscale Modeling Approach Using Lumped Kinetics for Pyrolysis of Plastic Waste
No full textPlastic waste poses a global environmental problem and one day the State of Qatar needs to address it in line with its 2030 vision. The pyrolysis of plastic waste is a thermochemical conversion process that has recently gained considerable attention for its potential to convert plastic waste while generating valuable chemicals. Despite extensive research on plastic waste pyrolysis, there is a notable gap in the literature regarding the exploration of connections between different scales���experimental, kinetic, reactor, and process scales. This thesis aims to address this gap by establishing a multiscale approach, bridging the transition from laboratory-scale experiments to process models for plastic waste pyrolysis by utilizing lumped kinetic models, demonstrated for the cases of polyolefins.
A methodology is developed to link the scales, followed by the creation of a sequence chart representing all the necessary steps to complete each stage. This approach is explored through three case studies that vary either in lumped kinetics, plastic feedstock, or component selection. For each case, a lump kinetic model is integrated into 1D pseudo-homogeneous tubular reactor model, that is developed using MATLAB. Parametric studies were conducted for residence time (0-2 hours), wall temperature (650-950 K), and overall heat transfer coefficients (300, 500, and 1000 W/m����K) within the reactor. With the insights gained from these parametric studies, selected scenarios based on the minimum reactor energy and maximum plastic consumption were integrated into Aspen Plus to construct process models for determining mass and energy requirements. Additionally, the fourth case was subjected to techno-economic analysis, where the total annualized cost, profit, and circularity indicators were calculated and compared with other thermochemical plastic waste routes.
Through this research, the gaps associated with multi-scale modeling aspects in literature are aimed to be addressed, and a framework is sought to be established that seamlessly connects information from each scale. By achieving this goal, a holistic understanding of the entire plastic waste pyrolysis chain is aimed to be provided to decision-makers, empowering them to be informed about implementing plastic waste pyrolysis as an effective and sustainable solution for waste management. The results are within the range of other plastic waste management processes, showcasing the practical implementation and gap-bridging capabilities of the approach
The Effects of a Structured Literacy Computer Program Implemented at Home on the Early Literacy Skills of Preschool Children
No full textThe purpose of the current study was to examine the effects of a computer program on the early literacy skills of preschool children, the relationship between fidelity to the intervention and improvement in literacy skills, and the reported satisfaction with the program. Forty-two four- and five-year-old children were randomly assigned to an intervention group, which used the OgStar Reading Early Reader iPad computer program/app, or a control group, which used the IXL Math computer program/app. The recommendation was to engage with the program for 15- 20 minutes per day for five days a week over a period of eight weeks in the summer prior to kindergarten. Three DIBELS measures were used to assess early literacy skills: Letter Naming Fluency (LNF), Phoneme Segmentation Fluency (PSF), and Nonsense Word Fluency (NWF). Parents submitted fidelity data about the number of lessons completed and completed a survey to assess their opinions regarding the use of the program. A total of 33 children completed posttests. Using linear regression and controlling for pretest score, students in the intervention group scored statistically significantly higher on LNF posttests (g = 0.41, p = .025) and NWF- correct letter sounds posttests (g = 0.52, p = .009) over the control group. No statistically significant differences were found between the groups for PSF (g = 0.19, p = .458) or NWF- words recoded correctly (g = 0.61, p = .057). Overall, fidelity to the planned intervention varied across participants. The number of lessons completed was moderately related to participant gains in LNF (r = 0.38), NWF- correct letter sounds (r = 0.31), and NWF- words recoded correctly (r = 0.36). Parent reported level of satisfaction with the app was generally positive. Parents reported they thought their child learned new skills (4.8/6.0) and would recommend it to other parents (4.5/6.0). These findings provide some initial support that the use of the OgStar Early Reader app may improve alphabetic knowledge for preschool children. Further study of the program and its effectiveness for a variety of participants and contexts is needed
The Economic and Financial Potential of Vineyards in the Texas Hill Country
No full textThere has been a substantial increase in the population of the Texas Hill Country over the last
decade (Hill Country Alliance 2008). Currently, the population in the Texas Hill Country is 3.1
million and is projected to increase to 4.3 million by the year 2030 (Hill Country Alliance 2008).
With respect to agricultural production activities in the area, a major downside of the population influx occurring is that property values have increased at a rapid rate in association with the resulting high demand (American Society of Farm Managers and Rural Appraisers 2019, p. 54). With the rapid influx of people into this region of the state expected to continue, many rural property owners are looking for sources of income that could help offset the increase in property taxes associated with the steadily increasing land prices. In this regard, the potential that vineyards have in the Texas Hill Country, due to their proximity to wineries, presents an interesting question, ���Are vineyards economically and financially feasible for current and potential vineyard operators as well as investors?���
While the concept of growing wine grapes to offset the cost of land and associated property taxes is intriguing, there are several questions that present themselves. Potential producers, and investors, do not have all the necessary information needed to make an informed decision as to if growing grapes is a sound financial endeavor. This thesis is an investigation of a series of scenarios that consider the relative effects of several factors on the potential profitability of a hypothetical Texas Hill Country vineyard operation. Evaluation of these projections allows economic and financial evaluation of the potential of self-sustaining vineyards in the Texas Hill Country, providing information to producers and investors interested in growing grapes in the Texas Hill Country.
This thesis includes a detailed documentation of the assumptions and parameters for three
vineyards of varied sizes as well as the economic and financial results for each size for the
specified scenarios. High land prices contribute to substantial initial capital investment
requirements which places an immediate financial strain on the vineyard from day one. Based
on the established parameters for this thesis, the potential for vineyards in the Texas Hill Country to be economically and financially attractive to potential investors and producers is unlikely. The limitations of this thesis and suggestions for future research are identified, with intentions of identifying pathways for further evaluating the potential of vineyard investments and the value of vineyards in complementing winery operations
A mm-Wave Concurrent Dual-Band Dual-Beam Phased Array Receiver Front-End in 22 nm FDSOI CMOS
No full textA mm-Wave concurrent dual-band (28 and 39 GHz) dual-beam phased array multi-input���multi output (MIMO) receiver front end with mid-band rejection was designed and fabricated in 22 nm Fully Depleted Silicon on Insulator (FDSOI) CMOS process. This phased array receiver front end has 4 inputs and 2 output streams with fully connected configuration where takes advantage of sharing LNA and quadrature network and using a unique PS structure which allows power and area saving. The measured 3-dB gain bandwidth is from 23 to 30 GHz for the lower bandwidth a peak gain of 21 dB at 29 GHz, and 36 to 40 GHz for the upper bandwidth a peak gain of 18 dB at 38.5 GHz, and a NF minimum of 6 and 7 dB at 28 and 37 GHz, respectively. The 21 dB mid-band rejection at 33.5 GHz is provided by the LNA to attenuate the out-of-band unwanted interference helping the relaxing the linearity requirement. The entire single-channel receiver front end achieves IIP3 varying from -18 dBm to -11 dBm, and input 1-dB compression point varying from -25 dBm to -18 dBm. The front end has 5-bit phase control and 7-dB gain control achieving the RMS phase and gain errors less than 6 deg and 1.2 dB, respectively, enabling orthogonality. This array demonstrates the concurrent functionality, and carrier aggregation for over-the-air beam steering and EVM measurements. The chip has a length of 2738 ��m, a width of 1808 ��m, and an area of 4.95 mm2 including all DC, RF pads, and decoupling capacitors