Dialogue as a Tool for Meaning Making

In order to empower citizens to analyze the effects, risk, and value of science, a knowledge of scientific concepts is necessary (Mejlgaard, 2009). The formal educational system plays a role in this endeavor (Gil-Perez & Vilches, 2005). One proposed constructivist practice is the use of social learning activities using verbalized, shared cognition among learners. In an effort to investigate the effects of verbally shared cognition, this project sought to determine if social learning opportunities affect the mastery of content in gateway biology courses and to identify the types of dialogue students engage in during cognitive collaboration. Fifty-seven students enrolled in a small southern community college were randomly assigned into treatment groups for each of nine units of instruction. The treatment variable was participation in verbalized social learning activities. Treatment differences based on a pretest/posttest design were analyzed using various statistical methods and recorded student discussions were analyzed for characteristics of talk based on a model developed by Mercer. Findings support the use of social learning activities as a way to improve content knowledge. Students in the treatment group had higher posttest and gain scores than those in the control group, with statistical significance reached in some cases. Types of talk were examined to support the constructivist method of learning. Findings support the use of non-confrontational talk as the vector of meaning making within the classroom

Superpositions of light fields carrying orbital angular momentum.

Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.The work presented in this thesis is centred on the generation of superimposed optical fields which each carry orbital angular momentum (OAM) and the development of OAM measurement techniques. Optical fields which carry OAM have found applications ranging from optical tweezing to quantum cryptography. Due to the fact that they offer a potentially infinite-dimensional state space, much interest has been generated in the measurement of OAM in optical fields, in order for higher-dimensional quantum information processing to be realised. In this study we generate superpositions of higher-order Bessel beams and show that even though we can create a field which carries no overall OAM, we can still witness an angular rotation in the intensity profile of the beam. We also develop two new OAM measurement techniques: (1) a robust odd-even-OAM interferometer and (2) a method to measure the OAM density of an optical field by means of a single spatial light modulator (SLM). In the first chapter we give an overview of the literature regarding optical OAM, followed by the derivation of the Helmholtz wave equation from Maxwell’s equations. We illustrate that helically-phased beams, having a phase factor of exp(ilθ), possess a well-defined OAM. Definitions for the fundamental Gaussian mode, as well as two OAM-carrying modes: Laguerre-Gaussian (LG) and Bessel-Gaussian (BG) modes are also given. Since a majority of this thesis involves generating superimposed OAM fields as well as the measurement of OAM, chapter 2 contains detailed discussions on the optical components used to generate and measure OAM. In section 2.9 we present one of our contributions to the field of OAM-measurement, which involves a stable Dove-prism embedded Mach-Zehnder interferometer, capable of sorting 41 OAM states into odd and even ports with a contrast ranging from 92% to 61%. We implement the Dove prism embedded Mach-Zehnder interferometer to mimic an amplitude damping channel for OAM states in chapter 3. Our device is useful in modelling a ‘lossy’ environment for OAM states. In chapter 4 we develop a new technique for the generation of superimposed Bessel beams through the use of a single digital hologram and theoretically and experimentally show that even though the superimposed Bessel beams can be constructed to produce no overall OAM, a rotation in the beam’s intensity profile is still present, as the field propagates. This rotation is due to the differing longitudinal wave-vectors present in the field and we make quantitative, experimental measurements of the angular rotation rates, which are in very good agreement with our theoretical predictions. We also show that the far-field of these superimposed Bessel beams, exhibit no rotation in their intensity profile and we offer a theoretical explanation for this occurrence. In chapter 5, we adapt our technique for generating superimposed Bessel beams to create non-diffracting speckle fields, which are known to possess optical vortices, and show that by controlling the standard deviation of the phase distribution within the digital hologram, we are able to control the evolution of the non-diffracting speckle field into a non-diffracting zero-order Bessel beam. Our final chapter contains a novel technique for the measurement of the OAM density of optical fields, by implementing two optical components: an SLM and a lens

Re-Engineering the ISS Payload Operations Control Center During Increased Utilization and Critical Onboard Events

With an increase in utilization and hours of payload operations being executed onboard the International Space Station (ISS), upgrading the NASA Marshall Space Flight Center (MSFC) Huntsville Operations Support Center (HOSC) ISS Payload Control Area (PCA) was essential to gaining efficiencies and assurance of current and future payload health and science return. PCA houses the Payload Operations Integration Center (POIC) responsible for the execution of all NASA payloads onboard the ISS. POIC Flight Controllers are responsible for the operation of voice, stowage, command, telemetry, video, power, thermal, and environmental control in support of ISS science experiments. The methodologies and execution of the PCA refurbishment were planned and performed within a four-month period in order to assure uninterrupted operation of ISS payloads and minimal impacts to payload operations teams. To vacate the PCA, three additional HOSC control rooms were reconfigured to handle ISS real-time operations, Backup Control Center (BCC) to Mission Control in Houston, simulations, and testing functions. This involved coordination and cooperation from teams of ISS operations controllers, multiple engineering and design disciplines, management, and construction companies performing an array of activities simultaneously and in sync delivering a final product with no issues that impacted the schedule. For each console operator discipline, studies of Information Technology (IT) tools and equipment layouts, ergonomics, and lines of sight were performed. Infusing some of the latest IT into the project was an essential goal in ensuring future growth and success of the ISS payload science returns. Engineering evaluations led to a state of the art Video Wall implementation and more efficient ethernet cabling distribution providing the latest products and the best solution for the POIC. These engineering innovations led to cost savings for the project. Constraints involved in the management of the project included executing over 450 crew-hours of ISS real-time payload operations including a major onboard communications upgrade, SpaceX un-berth, a Soyuz launch, roll-out of ISS live video and interviews from the POIC, annual BCC certification and hurricane season, and ISS simulations and testing. Continuous ISS payload operations were possible during the PCA facility modifications with the reconfiguration of four control rooms and standup of two temporary control areas. Another major restriction to the project was an ongoing facility upgrade that included a NASA Headquarters mandated replacement of all electrical and mechanical systems and replacement of an external generator. These upgrades required a facility power outage during the PCA upgrades. The project also encompassed console layout designs and ordering, amenities selections and ordering, excessing of old equipment, moves, disposal of old IT equipment, camera installations, facility tour re-schedules, and contract justifications. These were just some of the tasks needed for a successful project. This paper describes the logistics and lessons learned in upgrading a control center capability in the middle of complex real-time operations. Combining the efficiencies of controller interaction and new technology infusion were prime drivers for this upgrade to handle the increased utilization of science research on ISS. The success of this project could not jeopardize the current operations while these facility upgrades occurred

BLM rangeland: Has the condition improved?

Whose Home Is the Range, Anyway?: The latest research is confirming that in the West\u27s fragile public lands, cattle are often bad news for wildlife. This is the title and headline of Lisa Drew\u27s article in the December/January 1994 issue of National Wildlife. It shows a picture of what looks like a wasteland with only cattle, manure and a fence, no vegetation (Drew, 1994). Inside the article, Drew quotes biologist Bob Ohmart at Arizona State University\u27s Center for Environmental Studies as saying, Livestock grazing is without a doubt the greatest threat to western wildlife (p. 15). Drew contends that, The more researchers learn, the more of a villain seems the cow, which eats 12,000 pounds of plants a year and lingers in riparian areas (p. 16). Livestock grazing on the public rangelands has come under much criticism in both the past and the present. In a 1977 report to the Congress by the Comptroller General of the United States, the first sentence was, The Nation\u27s public rangelands have been deteriorating for years and, for the most part, are not improving (p. i). Many environmentalists agree with this statement today. In Ending the Range Wars?, William Riebsame writes: Environmentalists claim that much of the federal rangeland is overgrazed and that low grazing fees and lax agency oversight give ranchers defacto control of the land and make them careless of the resource (p. 6). On the other end of the spectrum is the statement by Thadis Box, I believe the range, on a whole, is in the best condition it has been in this century (Box, 1988, p. 1). Box is a Certified Range Management Consultant, past president of the Society for Range Management, professor and Dean Emeritus of Natural Resources at Utah State University. Box made the same statement in 1979 in a paper presented for the Rangelands Policy Symposium in Tucson, Arizona (Box, 1979). The purpose of this paper is to examine some of the available data concerning range condition on BLM administered lands, and to determine the trend for those lands

Use of a three-dimensional in vitro alginate hydrogel culture model to direct zonal formation of growth plate cartilage

Growth plate cartilage is found at the ends of long bones, and is responsible for the growth of the bones as a person is developing. The architecture of this growth plate is very specific and contributes to proper function to allow for bone growth. Although there are many factors known to be involved in the formation of the growth plate and its proper regulation, the exact mechanisms involved in these processes are not fully understood. So far, previous attempts to recapitulate a functioning growth plate in vitro have been unsuccessful. In this study, a new method to study the growth plate and the mechanisms involved in its formation was developed using an in vitro cell culture system made of alginate hydrogel scaffolds. Chondrocytes isolated from neonatal mouse growth plates were encapsulated within hydrogel beads and cultured. Please click Additional Files below to see the full abstract

Robust interferometer for the routing of light beams carrying orbital angular momentum

We have developed an interferometer requiring only minimal angular alignment for the routing of beams carrying orbital angular momentum. The Mach–Zehnder interferometer contains a Dove prism in each arm where each has a mirror plane around which the transverse phase profile is inverted. One consequence of the inversions is that the interferometer needs no alignment. Instead the interferometer defines a unique axis about which the input beam must be coupled. Experimental results are presented for the fringe contrast, reaching a maximum value of 93±1%

A versatile quantum walk resonator with bright classical light

In a Quantum Walk (QW) the "walker" follows all possible paths at once through the principle of quantum superposition, differentiating itself from classical random walks where one random path is taken at a time. This facilitates the searching of problem solution spaces faster than with classical random walks, and holds promise for advances in dynamical quantum simulation, biological process modelling and quantum computation. Current efforts to implement QWs have been hindered by the complexity of handling single photons and the inscalability of cascading approaches. Here we employ a versatile and scalable resonator configuration to realise quantum walks with bright classical light. We experimentally demonstrate the versatility of our approach by implementing a variety of QWs, all with the same experimental platform, while the use of a resonator allows for an arbitrary number of steps without scaling the number of optics. Our approach paves the way for practical QWs with bright classical light and explicitly makes clear that quantum walks with a single walker do not require quantum states of light