Implementing Institute of Electrical and Electronics Engineers (IEEE) 802.11 Standard Medium Access Control Protocol for Wireless Local Area Networks (LANS) on a Laboratory Hardware Prototype

Wireless Local Area Networks (LANs) are extremely convenient, flexible, and easy to deploy. All LANs in which multiple hosts must access the same medium use a Medium Access Control (MAC) protocol to coordinate channel access. The MAC is part of the Data Link Layer of the Open Systems Interconnection (OSI) Reference Model. One MAC protocol in extensive use today is the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. Since IEEE 802.11 devices are so prevalent in today s world, many researcher are exploring modifications and enhancements to the protocol. There are several well developed analytical and simulation models for IEEE 802.11 available to researchers, yet one significant obstacle remains: the lack of a means to obtain experimental data based on proposed protocol changes. Without real world experimental data, researchers lack the ability to test out their proposals in a real world environment. To fill this need, this thesis created a hardware prototype from which researchers can obtain experimental data about IEEE 802.11. This hardware prototype can now be used by researchers to gain real world data on their proposed modifications to IEEE 802.11

Integrating Weed Management Practices to Enhance Productivity of Grazed Pastures

As animal grazing has intensified within Kentucky and the surrounding region problematic weeds such as tall ironweed, spiny amaranth, horsenettle, buttercup, common cocklebur, and thistles have been increasing. These weeds become prominent in pastures because they have spines, thorns, or are unpalatable to animals. Animals selectively graze and avoid these weedy plants and with intensive grazing practices their populations are allowed to increase. Livestock producers are seeking ways to increase pasture productivity by minimizing the impact of these and other weeds on grazed lands

Epidural Analgesia Decreases Narcotic Requirements in Low Level Spina Bifida Patients Undergoing Urologic Laparotomy for Neurogenic Bladder and Bowel

Purpose Concern of anatomical anomalies and worsening neurologic symptoms has prevented widespread use of epidural catheters in patients with low level spina bifida (LLSB). We hypothesize that thoracic epidural placement in the T9-T10 interspace is safe and decreases narcotic requirements in LLSB patients following major open lower urinary tract reconstruction (LUTR). Materials and Methods We reviewed consecutive LLSB patients who had LUTR and epidurals for post-operative pain control. Controls were LLSB patients who received single shot transversus abdominis plane (TAP) blocks with similar procedures. Complications from epidural placement, including changes in motor and sensory status were recorded. Opioid consumption was calculated utilizing equivalent IV morphine doses. Mean and maximum pain scores on post-operative day (POD) 0-3 were calculated. Results 10 LLSB patients who had lower urinary tract reconstruction and epidurals were matched to 10 LLSB patients who had lower urinary tract reconstruction and transverse abdominis plane blocks. Groups were demographically similar. All had full abdominal sensation and functional levels at or below L3. No epidural complications or changes in neurological status were noted. The epidural group had decreased opioid consumption on POD 0-3 (0.75 mg/kg vs. 1.29 mg/kg, p=0.04). Pain scores were similar or improved in the epidural group. Conclusions Thoracic epidural analgesia appears to be a safe and effective opioid sparing option to assist with post-operative pain management following lower urinary tract reconstruction in LLSB patients

Epidemiological evidence for a hereditary contribution to myasthenia gravis: A retrospective cohort study of patients from North America

OBJECTIVES: To approximate the rate of familial myasthenia gravis and the coexistence of other autoimmune disorders in the patients and their families. DESIGN: Retrospective cohort study. SETTING: Clinics across North America. PARTICIPANTS: The study included 1032 patients diagnosed with acetylcholine receptor antibody (AChR)-positive myasthenia gravis. METHODS: Phenotype information of 1032 patients diagnosed with AChR-positive myasthenia gravis was obtained from clinics at 14 centres across North America between January 2010 and January 2011. A critical review of the epidemiological literature on the familial rate of myasthenia gravis was also performed. RESULTS: Among 1032 patients, 58 (5.6%) reported a family history of myasthenia gravis. A history of autoimmune diseases was present in 26.6% of patients and in 28.4% of their family members. DISCUSSION: The familial rate of myasthenia gravis was higher than would be expected for a sporadic disease. Furthermore, a high proportion of patients had a personal or family history of autoimmune disease. Taken together, these findings suggest a genetic contribution to the pathogenesis of myasthenia gravis

Techniques to stimulate and interrogate cell–cell adhesion mechanics

Cell–cell adhesions maintain the mechanical integrity of multicellular tissues and have recently been found to act as mechanotransducers, translating mechanical cues into biochemical signals. Mechanotransduction studies have primarily focused on focal adhesions, sites of cell-substrate attachment. These studies leverage technical advances in devices and systems interfacing with living cells through cell–extracellular matrix adhesions. As reports of aberrant signal transduction originating from mutations in cell–cell adhesion molecules are being increasingly associated with disease states, growing attention is being paid to this intercellular signaling hub. Along with this renewed focus, new requirements arise for the interrogation and stimulation of cell–cell adhesive junctions. This review covers established experimental techniques for stimulation and interrogation of cell–cell adhesion from cell pairs to monolayers

A point process framework for modeling electrical stimulation of the auditory nerve

Model-based studies of auditory nerve responses to electrical stimulation can provide insight into the functioning of cochlear implants. Ideally, these studies can identify limitations in sound processing strategies and lead to improved methods for providing sound information to cochlear implant users. To accomplish this, models must accurately describe auditory nerve spiking while avoiding excessive complexity that would preclude large-scale simulations of populations of auditory nerve fibers and obscure insight into the mechanisms that influence neural encoding of sound information. In this spirit, we develop a point process model of the auditory nerve that provides a compact and accurate description of neural responses to electric stimulation. Inspired by the framework of generalized linear models, the proposed model consists of a cascade of linear and nonlinear stages. We show how each of these stages can be associated with biophysical mechanisms and related to models of neuronal dynamics. Moreover, we derive a semi-analytical procedure that uniquely determines each parameter in the model on the basis of fundamental statistics from recordings of single fiber responses to electric stimulation, including threshold, relative spread, jitter, and chronaxie. The model also accounts for refractory and summation effects that influence the responses of auditory nerve fibers to high pulse rate stimulation. Throughout, we compare model predictions to published physiological data and explain differences in auditory nerve responses to high and low pulse rate stimulation. We close by performing an ideal observer analysis of simulated spike trains in response to sinusoidally amplitude modulated stimuli and find that carrier pulse rate does not affect modulation detection thresholds.Comment: 1 title page, 27 manuscript pages, 14 figures, 1 table, 1 appendi

System Modeling of Lunar Oxygen Production: Mass and Power Requirements

A systems analysis tool for estimating the mass and power requirements for a lunar oxygen production facility is introduced. The individual modeling components involve the chemical processing and cryogenic storage subsystems needed to process a beneficiated regolith stream into liquid oxygen via ilmenite reduction. The power can be supplied from one of six different fission reactor-converter systems. A baseline system analysis, capable of producing 15 metric tons of oxygen per annum, is presented. The influence of reactor-converter choice was seen to have a small but measurable impact on the system configuration and performance. Finally, the mission concept of operations can have a substantial impact upon individual component size and power requirements

Global application of a regional frequency analysis on extreme sea levels

Coastal regions face increasing threats from rising sea levels and extreme weather events, highlighting the urgent need for accurate assessments of coastal flood risk. This study presents a novel approach to estimating global Extreme Sea Level (ESL) exceedance probabilities, using a Regional Frequency Analysis (RFA) approach. The research combines observed and modelled hindcast data to produce a high-resolution (~1 km) dataset of ESL exceedance probabilities, including wave setup, along the entire global coastline, excluding Antarctica.The RFA approach offers several advantages over traditional methods, particularly in regions with limited observational data. It overcomes the challenge of short and incomplete observational records by substituting long historical records with a collection of shorter but spatially distributed records. This spatially distributed data not only retains the volume of information but also addresses the issue of sparse tide gauge coverage in less populated areas and developing nations. The RFA process is illustrated using Cyclone Yasi (2011) as a case study, demonstrating how the approach can significantly improve the characterisation of ESLs in regions prone to tropical cyclone activity.In conclusion, this study provides a valuable resource for quantifying global coastal flood risk, offering an innovative methodology that can contribute to preparing for, and mitigating against, coastal flooding

The FIRST-Optical-VLA Survey for Lensed Radio Lobes

We present results from a survey for gravitationally lensed radio lobes. Lensed lobes are a potentially richer source of information about galaxy mass distributions than lensed point sources, which have been the exclusive focus of other recent surveys. Our approach is to identify radio lobes in the FIRST catalog and then search optical catalogs for coincident foreground galaxies, which are candidate lensing galaxies. We then obtain higher-resolution images of these targets at both optical and radio wavelengths, and obtain optical spectra for the most promising candidates. We present maps of several radio lobes that are nearly coincident with galaxies. We have not found any new and unambiguous cases of gravitational lensing. One radio lobe in particular, FOV J0743+1553, has two hot spots that could be multiple images produced by a z=0.19 spiral galaxy, but the lensing interpretation is problematic.Comment: 38 pages, 18 figures, aastex, accepted to A