On behavior of the fifth algebraic transfer

In this paper, we show that Singer's fifth transfer is not an epimorphism in degree 11. More precisely, it does not detect the element P(h_2) in Ext_A^{5,16}(F_2,F_2).Comment: This is the version published by Geometry & Topology Monographs on 14 November 200

To eat or not to eat: Urbanization and the foraging behaviors of Michigan passerines

Urbanization creates novel problems for wildlife, potentially altering the foraging behavior of passerine birds. Foraging is driven by factors like food preference and food accessibility; the foraging of urban birds may be more innovative due to frequent exposure to unfamiliar items. I hypothesized that high novelty exposure in urban birds would promote faster discovery and longer visits to novel feeders compared to rural conspecifics. Additionally, I hypothesized that birds would prioritize food quality over access regardless of habitat, but when faced with barriers, urban birds would be better at accessing food compared to rural birds because of frequent exposure to novel obstacles. Recording bird visitations to paired bird feeders of differing food quality, I found that feeder discovery was not significantly different between the seed types or habitats. Rural birds spent half as much time at low access feeders compared to urban birds; when feeders were caged, rural birds discovered both seed types more quickly than the urban counterparts. Additionally, higher-quality food had greater consumption in both environments regardless of accessibility, although rural birds removed more low-quality food than urban birds when the more nutritional option was obstructed. This study reveals the importance of food preferences in driving avian feeding behaviors and how bird communities may be shaped by the food quality and degree of fragmentation of the habitat

Feasibility of Integrating Tripterygium wilfordii into Modern Cancer Therapy for Increased Efficacy and Minimal Toxicity

Cancer is the second leading cause of death in the U.S. and millions of novel cancer cases are being diagnosed each year. While chemotherapy and ionizing radiation are effective treatments against these malignant tumors, the adverse effects that accompany such treatments are devastating. In order to find alternative treatment methods with less side effects, we turn to Eastern herbal medicine. Recent scientific research has found that Tripterygium wilfordii, an herbal medicine traditionally used to treat inflammation in China, contains compounds (triptolide and celastrol) that prevent the growth of solid tumors, induce apoptosis, and prevent metastasis of developed tumors. Investigations on these compounds on various cancer cells lines (in vitro and in vivo) have revealed insight into their mechanism, mode of action, and toxicity. In order to circumvent the potentially fatal side effects of triptolide and celastrol, it was proposed that roots of T. wilfordii, from which the compounds are extracted, be used as a treatment for cancer. Methods for testing the efficacy and toxicity of the roots on the different cell lines previously studied are outlined in this paper. If the results from the proposed experiment conflict with expectation, then future studies on combination drugs using triptolide and celastrol with other non-bioactive compounds within the roots should be done to develop new anti-cancer drugs with low toxicity.https://scholarscompass.vcu.edu/uresposters/1165/thumbnail.jp

Doctor of Philosophy

dissertationDataflow pipeline models are widely used in visualization systems. Despite recent advancements in parallel architecture, most systems still support only a single CPU or a small collection of CPUs such as a SMP workstation. Even for systems that are specifically tuned towards parallel visualization, their execution models only provide support for data-parallelism while ignoring taskparallelism and pipeline-parallelism. With the recent popularization of machines equipped with multicore CPUs and multi-GPU units, these visualization systems are undoubtedly falling further behind in reaching maximum efficiency. On the other hand, there exist several libraries that can schedule program executions on multiple CPUs and/or multiple GPUs. However, due to differences in executing a task graph and a pipeline along with their APIs being considerably low-level, it still remains a challenge to integrate these run-time libraries into current visualization systems. Thus, there is a need for a redesigned dataflow architecture to fully support and exploit the power of highly parallel machines in large-scale visualization. The new design must be able to schedule executions on heterogeneous platforms while at the same time supporting arbitrarily large datasets through the use of streaming data structures. The primary goal of this dissertation work is to develop a parallel dataflow architecture for streaming large-scale visualizations. The framework includes supports for platforms ranging from multicore processors to clusters consisting of thousands CPUs and GPUs. We achieve this in our system by introducing the notion of Virtual Processing Elements and Task-Oriented Modules along with a highly customizable scheduler that controls the assignment of tasks to elements dynamically. This creates an intuitive way to maintain multiple CPU/GPU kernels yet still provide coherency and synchronization across module executions. We have implemented these techniques into HyperFlow which is made of an API with all basic dataflow constructs described in the dissertation, and a distributed run-time library that can be used to deploy those pipelines on multicore, multi-GPU and cluster-based platforms

Comparing the Effects of Immediate vs. Delayed Differential Reinforcement of Zero Rate Behavior Schedules on Tic Suppression

Persistent Tic Disorder and Tourette Disorder are neuropsychiatric conditions characterized by motor and or/ vocal tics. Treatment surrounding tics involve pharmaceutical or behavior therapy. Individuals seeking behavior therapy receive habit reversal training (HRT) or comprehensive behavioral intervention for tics (CBIT). Much research demonstrates the efficacy of HRT and CBIT, however, as these treatments often teach effective tic suppression skills, it may be useful to better understand the behavioral contingencies that most effectively lead to suppression. This research aims to compare different schedules of reinforcement on tic suppression. Two individuals diagnosed with Tourette’s Disorder, ages 9-14, participated in this study. A multielement treatment design was used to compare three conditions, baseline (BL), immediate differential reinforcement of zero rate behavior (DRO-10s), and delayed differential reinforcement of zero rate behavior (delayed DRO). Tic frequencies were significantly higher during BL conditions compared to DRO-10s and delayed DRO across participants. Although DRO-10s and delayed DRO demonstrated robust decrease in tic frequency, the results between DRO conditions were undifferentiated. Self-reported urge to tic ratings decreased from pre-sessions rating in baseline sessions and increased following both DRO conditions. Only one participant reported a slight increase in urge to tic ratings following the initial baseline and one participant reported no change in self-reported urge to tic ratings in DRO10s condition. Urges precede tics were reported to be aversive, and while best practices would not recommend utilizing DRO procedures as a method to produce tic suppression, both participants\u27 one trial preference assessment implies a general reinforcing value for suppressing tics

Defining the role of cytosolic iron-sulfur cluster assembly targeting complex in identification of iron-sulfur cluster proteins

Iron sulfur (FeS) clusters are ubiquitous cofactors required for numerous fundamental biochemical processes, including DNA replication and repair, transcription, and translation. In the cell, these metallocofactors require a dedicated protein pathway for assembly. The Cytosolic Iron Sulfur Cluster Assembly (CIA) pathway is conserved across higher-level eukaryotes and is responsible for building and inserting these cofactors into the FeS proteins that need them. A major unsolved problem in the FeS cluster biogenesis field is how so many diverse FeS proteins are identified for cluster insertion. Several studies have identified a multiprotein complex containing Cia1, Cia2, and Met18 as the CIA targeting complex responsible for FeS cluster recognition and target maturation. The CIA targeting complex has been shown to associate with an FeS cluster protein, Nar1. Nar1 is a CIA factor that plays an unknown role in cluster transfer. Little information is known about the structure of the CIA targeting complex its mechanism of FeS cluster protein recognition. In this thesis, I investigate the architecture of the CIA targeting complex as well as the role each subunit plays in identification of apo-proteins and iron-sulfur cluster insertion. Previous proteomic and cell biological studies from the Lill lab propose that the CIA targeting complex exists as a mixture of discrete complexes in vivo. Each of these complexes is responsible for recognizing a distinct subset of targets. Herein, we utilize affinity co-purification and size exclusion chromatography investigate connectivity of the targeting complex, identify stable subcomplexes, and define their roles in recognizing our two model targets Rad3 and Leu1. We determine the CIA targeting complex contains one Met18, two Cia1, and four Cia2 polypepides. This complex is required to recognize Leu1. Our experiments reveal the formation of the stable subcomplexes Cia1-Cia2 and Met18-Cia2, which is sufficient to identify to Rad3. We also interrogate the role of Nar1 in binding to targets and cluster transfer, excluding the model that it acts as an adapter for cluster transfer. Furthermore, using site directed mutagenesis, combined with our co-purification and in vivo assays, we map the key interfaces required to form the targeting complex and investigate how their mutations impacts CIA function in vivo. We identify the binding site of Cia1 on Cia2, as well as the general region in which Cia2 binds to Met18. Through these experiments, we shed light on the role these subunits of CIA targeting complex and Nar1 play in FeS target recognition and FeS cluster transfer