Increased Response Variability and Attentional Lapses After Chronic Cocaine Self-Administration

In humans, cocaine use has long been associated with poor attentional control and decreased efficiency in goal-oriented behavior. Animal models of these stereotypic drug effects, however, have thus far failed to produce quantifiable data sets in part because of a lack of species differences and analysis techniques. Recent work (Hervey et al. 2006) has successfully quantified attentional lapses in disorders such as ADHD through the analysis of response time variations in simple tasks, but this analysis has yet to be applied to the drug abuse scenario. To determine the effects of chronic cocaine administration on response time variability, 14 rhesus macaque monkeys (8 cocaine administering and 6 performance-matched controls) were subjected to a 50 trial simple attention task. This task was performed W-F prior to cocaine self-administration sessions in the test group. Treatment groups were compared to both each other and to baseline task sessions recorded prior to beginning the administration paradigm. In addition to typical measures of variability, an ex-Gaussian response time analysis was performed to quantify the contribution of attentional lapses to overall variability. The cocaine-administering group had a significantly higher response time standard deviation than their pre-administration sessions (p<0.05). No difference was observed between pre- and post-administration sessions for the control group. When ex-Gaussian methods were applied to the response time datasets, no differences were observed between groups in the normal mean (mu), suggesting that the variability increase in the cocaine group was due to an increased skew in the right tail of the response time distribution. Indeed, the cocaine group showed a significant increase in the value of tau(exponential value representing the distribution tail magnitude) post-administration versus tau pre-administration (p<0.05). These data suggest that cocaine administration leads to increased behavioral variability in simple response time tasks, and that this variability increase is primarily due to the prevalence of abnormally long responses. Similar results have been demonstrated in clinical disorders such as ADHD, suggesting both the relevance of the primate model in studies of attentional processing and the possible similarity in affected brain regions or transmitter systems

Single-particle levitation system for automated study of homogeneous solute nucleation

We present an instrument that addresses two critical requirements for quantitative measurements of the homogeneous crystal nucleation rate in supersaturated aqueous solution. First, the need to perform repeated measurements of nucleation incubation times is met by automating experiments to enable programmable cycling of thermodynamic conditions. Second, the need for precise and robust control of the chemical potential in supersaturated aqueous solution is met by implementing a novel technique for regulating relative humidity. The apparatus levitates and weighs micron-sized samples in an electric field, providing access to highly supersaturated states. We report repeated observations of the crystal nucleation incubation time in a supersaturated aqueous sodium chloride droplet, from which we infer the nucleation rate

Improving Homeownership Among Poor and Moderate-Income Households

Looks at rates of homeownership, trends in federal low-income rental housing assistance, and types of homeownership programs for low-income households

READ Poster - Scrappy the Owl

READ Poster, featuring KSU mascot Scrappy the Owl. Book: The Book of North American Owls, by Helen Roney Sattler and Jean Zallinger. New York: Clarion Books, 1995.https://digitalcommons.kennesaw.edu/lib_market/1001/thumbnail.jp

Secure Dynamic Cloud-based Collaboration with Hierarchical Access

In recent years, the Cloud has emerged as an attractive way of hosting and delivering services over the Internet. This has resulted in a renewed focus on information security in the case where data is stored in the virtual space of the cloud and is not physically accessible to the customer. Through this thesis the boundaries of securing data in a cloud context, while retaining the benefits of the cloud, are explored. The thesis addresses the increasing security concerns of migrating to the cloud andutilising it for data storage.The research of this thesis is divided into three separate areas: securing data in an untrusted cloud environment, ensuring data access control in the cloud, and securing data outside the cloud in the user's environment. Each area is addressed by separate conceptual designs. Together these comprise a secure dynamic cloud-based collaboration environment with hierarchical access. To further validate the conceptual designs, proof of concept prototypes have been constructed.The conceptual designs have been devised by exploring and extending the boundaries of existing secure data-storage schemes, and then combining these with well-known security principles and cutting-edge research within the field of cryptography. The results of this thesis are feasible conceptual designs for a cloud-based dynamic collaboration environment. The conceptual designs address the challenges of secure cloud-based storage and allow the benefits of cloud-based storage to be utilised. Furthermore, this thesis provides a solid foundation for further work within this field

Scanning Activity Gravimetric Analysis

We introduce a new technique -- scanning activity gravimetric analysis (SAGA)for investigating phase transitions in semicrystalline polymers. Isothermal growth and dissolution of polymer crystallites within picogram to milligram samples are manifested by mass changes in response to changes in the activity of sorbed solvent vapor. Single charged particles are levitated and weighed in an electrostatic field, providing access to highly supersaturated states. Phase transitions are inferred from simultaneous sorption and light scattering measurements. Analogous to differential scanning calorimetry, scanning solvent activity up and down exposes broad transitions between the semicrystalline solid state and the dissolved state, which are influenced by sample history. We demonstrate repeated dissolution and crystallization of an 11 ng sample of poly(ethylene oxide) by controlling the activity of sorbed water vapor and observe self-nucleation of crystallites from partially and fully solvated states