Sunspots

This past semester the physics department began a study of the solar wind. Photographic plates have been sent up by balloon during periods of both maximum and minimum solar activity. The tracks made by high-energy particles on these 3mulsions are to be located and analyzed. Unfortunately, since the plates have yet to arrive, only a little practice scanning was done to become familiar with the technique. Meanwhile, an attempt has been made to gather information ab::mt the sun and the solar wind. This paper is a part of that work

Polarography

Jaroslav Heyrovsky invented the technique of polarography about 1920 at Charles University in Prague. With proper use one can obtain both qualitative and quantitative analyses of solutions of electro-oxidizable or electro-reducible substances at concentrations. The key part of a polarography is the dropping mercury electrode. This consists of a fine bore capillary tube connected to a large reservoir of mercury. Each tiny drop which falls from the capillary has approximately the same surface area and takes about the same time to form and fall. The greatest advantage is that each drop is actually a new electrode, and there is consequently no change in the electrode with time nor any chance of poisoning. The dropping mercury electrode is usually the cathode of the cell, and a calomel reference electrode is used for the anode. These are attached to a slide-wire potentiometer

A Study of the Physics Curriculum of Ouachita Baptist University

The purpose of this paper is to compare the physics curriculum of Ouachita Baptist University with those of several other colleges with the ultimate goal of finding what changes, if any, should by made. Four colleges and universities were used for comparison. Hendrix College is a Methodist college which had an enrollment of 757 during the 1965-66 school year. State College of Arkansas is a state-supported school with 3,129 students during the same year. Little Rock University is a private school which is aided by the city of Little Rock, Arkansas. It had 2,851 students in 1965-66. Southwestern at Memphis is a Presbyterian college with 993 enrolled. Ouachita itself had 1,785 students in the 1965-66 school year, and is, of course, Baptist school

The Release, Transport, and Utilization of Phosphorus from Bed-Sediments: A Study of a Eutrophic Littoral Cove on Beaver Lake in Northwest Arkansas

Eutrophication of surface waters not only impacts the environment but also water treatment processes, the most significant of which is from the effects of algae. During peak algal growth in many southern U.S. reservoirs, inflows that bring nutrients are at an annual minimum, and phosphorus released from bed-sediments is trapped in the hypolimnion. Littoral areas, described as the most productive zone of the lake, may be a possible source of phosphorus that fuels algal growth in the reservoir. I studied an isolated shallow cove in the War Eagle Creek arm of Beaver Lake in Northwest Arkansas to measure, quantify, and model the dynamics and transport of nutrients in littoral zones. A summary of the research problem, the statement of purpose, and associated hypothesis are provided in Chapter 1. Chapter 2 provides an overview of eutrophication as it relates to drinking water treatment, reservoirs, and zones within reservoirs. Also reviewed is the relationship of phosphorus (P) to reservoir eutrophication, internal loading as a source of P, and P cycling and transport within a reservoir. In Chapter 3, I present my study of sediment cores, temperature profiles, and dissolved oxygen (DO) profiles of the cove to determine the redox condition of the water overlying the bed-sediments and the associated sediment P release rates. Phosphorus release rates from bed-sediment incubations were as high as 2.02 mg m-2 d-1 under aerobic conditions and 4.05 mg m-2 d-1 under anaerobic. Variability in bottom DO concentrations of the littoral zone likely contribute to a cycling of aerobic and anaerobic conditions by changing the redox state at the sediment-water interface. When compared to whole-lake P release averages conducted for Beaver Lake, eutrophic coves were a disproportionate source of P within the reservoir, producing 6.5 times more P per unit area. Chapter 4 describes a study of how sediment P release and algal growth in littoral areas are connected. Sediment composition, equilibrium P concentration (EPCo), and aerobic P release rates were characterized for several sites within the cove. Core aerobic P release rates and EPCo both confirmed the release of P under aerobic conditions; however, it appears that algal demand sustained low dissolved P concentrations in the waters of the cove. This created a nutrient cycle where algae impose a nutrient gradient favoring the release of P by keeping concentrations of the waters overlying sediments below the EPCo. Chapter 5 describes a model developed to simulate thermoconvective flow and transport mechanisms between littoral and pelagic zones. Diurnal fluctuation in flow for surface and bottom waters indicated water moves in and out of the cove on a daily timestep. Overall, the general direction of flow was in along the bottom of the cove, and out along the top. The model and in situ P concentrations revealed that P is transported from bottom waters as they enter the cove to surface waters as they leave the cove. This process applied to all littoral areas of the reservoir would result in a major P transport mechanism to surface waters in late summer. Chapter 6 provides a synthesis of the three studies. Unique processes of the littoral zone make it a disproportionate source of P within a reservoir. P loads brought into the littoral zone along the bottom and P released out of littoral sediments are then available for transport out of the surface of the littoral zone. This P would then be available to be used by algae and replenish P losses in the epilimnion which occur through sedimentation. Our model and sampling indicate that late summer blooms of algae in Beaver Lake are likely fueled in part by P transport out of the littoral zone. The fundamental contribution of this research is the recognition of littoral areas as a significant source of internal P loading to fuel algal growth in reservoirs

Azithromycin (Zithromax®)

Azithromycin (Zithromax®, Pfizer, Inc., New York, NY) is a 15-membered-ring macrolide and the first azalide antibiotic. It is distinguished from other macrolides by its rapid and extensive penetration into intracellular and interstitial tissue compartments, accompanied by prolonged tissue and serum half-lives. Azithromycin shares the gram-positive activity of erythromycin but is more potent against gram-negative organisms. For urethritis and cervicitis caused by Chlamydia trachomatis, azithromycin is effective and well tolerated in a single dose of 1 g, a regimen recommended by the CDC. A 5-day dosage regimen is available for the treatment of community-acquired respiratory-tract and skin and skin-structure infections caused by susceptible organisms. Azithromycin provides short-duration, high-compliance, cost-effective regimens that should improve outcomes

Determining the Optimum Operating Parameters of a Unipolar PWM Inverter

This study presents a determination of the optimum operating parameters of a unipolar PWM inverter through theoretical and experimental analysis. The inverter is investigated in its simplest form without input DC-DC conversion or output filtering. The intent of this study is to understand the core of the inverter thoroughly before adding peripheral elements such as output filtering. Variations on the input voltage level and switching frequency were investigated to determine their impacts on the operation of the inverter and harmonics produced. Theoretical modeling and calculations confirmed by experimental measurements and analysis allow determination of the inverter operating conditions which allow highest converter efficiency with lowest distortion. Results suggest highest efficiency and lowest harmonic distortion is achieved at the lowest input voltage (just above the peak of the desired fundamental component) and lowest switching frequency independent of output power