Nanoparticle Necklace Network Arrays Exhibiting Room Temperature Single-Electron Switching

A single nanoparticle is one of the most sensitive electronic devices for sensing chemicals in a gas or liquid. The conductivity of a single Au nanoparticle is significantly modulated by the binding of a molecule that alters charge by just one electron. However, the single-electron sensitivity requires cryogenic temperatures and interconnection is not easy. A patterned two-dimensional network of one-dimensional nanoparticle necklaces made up of 10 nm Au particles are fabricated and shown to exhibit similar single-electron effect at room temperature. Furthermore, the long range conductivity of over 10’s of microns makes the structure easy to self-assemble onto conventional microelectronics circuitry. A device exhibiting single-electron effect is characterized by highly non-linear current-bias behavior where at bias, V \u3e VT current rises rapidly and scales as (V/VT – 1)ζ, where ζ ≥ 1 is the critical exponent and VT is the threshold voltage. Below VT, current does not flow. Thus, VT is the switching voltage and larger ζ signifies sharper switching characteristics. While arrays of one and two dimension are well known to exhibit appreciable VT at cryogenic temperatures, at ambient temperatures the blockade effect vanishes. The unique architecture of the necklace network results in a weak dependence of VT on temperature which leads to room temperature single-electron effect. The high sensitivity of the nanoparticle necklace network array at room temperature allows coupled live cells to electronically switch, or gate, the device through cellular metabolic activity. Additionally, the critical exponent, ζ, which is a measure of how current will rise during switching, can be significantly enhanced by cementing the necklaces with the dielectric material CdS, thereby greatly increasing the switching gain and sensitivity of the device. Given robust room temperature single-electron switching, enhanced ζ values, cellular coupling capability, and natural integrability with microelectronics circuitry, nanoparticle necklace network arrays have the potential to be implemented in a wide range of applications, such as, chemical sensors, biofuel cells, biomedical devices, and data storage devices. Adviser: Ravi F. Sara

Closing the Loop on Online Discussions

After teaching online for several semesters, I became increasingly frustrated with not seeing the value of having discussion board assignments. While I saw the value in having students engage with one another around certain topics, I felt like the loop was left open when it came to closing the discussion. In addition, my students were only required to respond to a limited number of their classmates during the discussion so they were not really getting a sound overview of the entire class discussion as they would in a traditional class. I decided to try something new. I began reading all of the discussion board posts (and replies) I would pull together common themes and common issues that arouse from the discussion. I would then write and send out a “summary paper” to the entire class about the discussion board for all students to read. I would clear up any misconceptions that I found in the discussion and would end the paper with a section on my thoughts on the topic. I would invite the students to further engage in the discussion with me if they were interested via email. My student’s response to this process was overwhelmingly positive. They enjoyed reading the synopsis of the discussion and expressed appreciation for learning my thoughts on the topic. It has become very clear that students want to receive feedback on the discussion and they really value the instructor’s viewpoints. Keywords Discussion Board, Closing the Loop, Online Discussion

Cross-kingdom interactions shape soil biogeochemistry in natural and agricultural ecosystems

Microorganisms influence life on earth in innumerable ways, including in medical, industrial, environmental, and agricultural contexts. Given the increasingly apparent consequences of climate warming, interest in how to better predict and manage Earth’s carbon sinks has never been greater. Soil, the largest terrestrial carbon sink, harbors an incredibly taxonomically and functionally diverse microbial community. These soil-dwelling microbes govern the fate of soil carbon and nutrients by cycling organic matter as they live, grow, and die. It has only been relatively recently that technological advancement has allowed for in-depth surveys of the vast diversity of soil microbes. High throughput analytical capabilities like next-generation DNA sequencing have resulted in an explosion of data confirming the importance of microbial communities in biogeochemical cycles. Nevertheless, many questions remain regarding microbially-mediated biogeochemical cycling in different environmental contexts (e.g., forest soil versus agricultural soil) and under changing environmental conditions (e.g., warming, agricultural intensification). In this dissertation, I examine the role of cross-kingdom interactions in shaping soil biogeochemistry under two different scenarios: 1) in a manipulated forest soil food web (animal-microbe interactions) and 2) early Miscanthus x giganteus cultivation on lands of varying disturbance histories using a suite of management strategies (plant-microbe interactions). I was broadly interested in how manipulating these interactions impacted soil carbon and nitrogen cycling and storage

Soil microbial succession following surface mining is governed primarily by deterministic factors

Understanding the successional dynamics governing soil microbial community assembly is a promising way to advance development of remediation strategies for lands disturbed by anthropogenic activities. The environmental and ecological influences shaping these communities following soil disturbance remain only partially understood. One example of a physical anthropogenic disturbance is extraction of minerals such as coal by surface mining. Surface mining removes natural soils and these soils may be replaced immediately on adjacent reclaimed areas or they may be stored in piles for later use. During reclamation, the soil is replaced on the landscape and the site is re-vegetated with grasses and trees. Throughout this process, the soil’s physical and chemical properties are drastically changed and soil microbial communities are spatially displaced, causing changes in water relations and nutrient cycling, as well as microbial abundance and community composition. These changes have a large effect in eliciting selective pressure on microbial taxa (i.e., deterministic processes). Dispersal and ecological drift are also important in shaping communities following disturbance (i.e., stochastic processes). We investigated the influence of stochastic and deterministic factors in shaping the soil microbiome following reclamation using formerly surface mined and reclaimed areas ranging from 2 to 32 years since reclamation occurred. A suite of soil chemical and physical parameters were measured to quantify the influence of deterministic processes and time was considered a proxy for stochastic processes. Sequencing of bacterial and fungal rRNA gene amplicons coupled with a linear modeling approach revealed that the soil microbiome following mine reclamation is shaped by both deterministic and stochastic influences, but that deterministic factors influence microbial succession more than stochastic factors by a ~4-fold difference. Further, while microbial biomass and diversity did not consistently increase with time following reclamation, the abundance of ecologically important bacterial taxa (e.g., Alpha- and Deltaproteobacteria) showed varying but significant responses, potentially due to the concomitant increases in soil nutrients such as carbon, nitrogen, and phosphorous. Our results suggest that management of deterministic soil characteristics over a sufficient time period could result in an accelerated recovery of the soil microbiome to pre-disturbance levels and composition, and therefore increased productivity of post-mining land uses

The Missing Link: Assessing the Reliability of Internet Citations in History Journals

This is the publisher's version, also available electronically from doi:10.1353/tech.0.002

The Perfect Marriage: Community Based and Online Learning

Community based projects are an integral part of most student’s higher education experience. It has become a popular pedagogical method that moves teaching and learning out of the traditional classroom and into the community where learning outcomes can be integrated into a particular context. Online learning has also emerged as a popular pedagogical practice in education and is continuing to gain popularity in higher education. Each has distinct benefits for teaching and learning and both provide instructors ways in which they can differentiate learning. To consider merging these two practices may seem challenging and ultimately, to some, impossible. Some may discredit the instructor’s ability to appropriately monitor community based learning activities while teaching a course from a distance and that the assessment of a student’s work will be too challenging. This presentation will provide examples and support for conducting community based learning projects into an online course and demonstrate ways in which assessment can be very authentic and meaningful. The examples used in this presentation are in the area of sport management but community based learning projects across other disciplines could also considered for these types of projects. Keywords Online Learning, Distance Learning, Community Based Learning, Service Learning, Assessmen

Identification of sleep apnea events using discrete wavelet transform of respiration, ECG and accelerometer signals

Sleep apnea is a common sleep disorder in which patient sleep patterns are disrupted due to recurrent pauses in breathing or by instances of abnormally low breathing. Current gold standard tests for the detection of apnea events are costly and have the addition of long waiting times. This paper investigates the use of cheap and easy to use sensors for the identification of sleep apnea events. Combinations of respiration, electrocardiography (ECG) and acceleration signals were analysed. Results show that using features, formed using the discrete wavelet transform (DWT), from the ECG and acceleration signals provided the highest classification accuracy, with an F1 score of 0.914. However, the novel employment of just the accelerometer signal during classification provided a comparable F1 score of 0.879. By employing one or a combination of the analysed sensors a preliminary test for sleep apnea, prior to the requirement for gold standard testing, can be performed

Catholic Higher Education and Latino(a) Students: Exploring the Experience of University Undergraduates

The experience of Latino(a) undergraduates at Notre Dame was the focus of this study. In general, the students had a positive experience at the university, but one that included challenges, including physical separation from family and familiar community. Family and spiritual supports were important to the Latino(a) students as they coped with difficulties they encountered at the university, than for a comparable sample of Anglo students attending Notre Dame

An Integrative Model of Inter- and Intragenerational Preconception Processes Influencing Birthweight in the United States

Social inequalities in birth weight are an important population health concern as low birth weight is one mechanism through which inequalities are reproduced across generations. Yet we don’t understand what causes adverse birth outcomes. This study draws together theoretic and empiric findings from disparate disciplines—sociology, economics, public health, and behavior genetics—to develop a new integrative intra- and inter-generational model of preconception processes influencing birth weight. This model is empirically tested using structural equation modeling and population-level data containing linked mother-daughter pairs from the National Longitudinal Survey of Youth (NLSY79) and the Children of the NLSY79 (N=1,580 mother-daughter pairs). Results reveal that birth weight is shaped by preconception factors dating back to women’s early life experiences as well as conditions dating back three generations, via integrative intra- and inter-generational processes. These processes reveal specific mechanisms through which social inequality can transmit from mothers to children via birth weight