Assay and Purification of Coxsackievirus B3

[vi], 74 leaves. Advisor: James C. JohnsonThe problem. Which of the available methodologies for the purification for Coxsackie virus B3 (CB3), a Picornavirus provide the highest degree of purity with the greatest yield. The procedure. Quantitative methods for the assay and purification of CB3 were developed. CB3 was propagated in buffalo green monkey (BGM) cells in tissue culture. The virus was released from the infected BGM cells by various methods. Purification methods included precipitations, differential, isopycnic, and rate zonal centrifugation. Virus purity was assessed by SDS-polyacrylamide gel electrophoresis. Findings: The plaque assay for CB3 was found to be reproducible and quantitative. The dose response curve of the assay was linear between 5 and 800 plaques on a 55 cm2 tissue culture dish. Maximum yields of CB3 were obtained from infected cells by treatment with sodium dodecyl sulfate (SDS). The overall yield of CB3 purified by isopycnic banding in cesium chloride was approximately 40% of the virus in the initial cell lysate. As judged by polyacrylamide gel electrophoresis in SDS, the purified virus, following rate zonal centrifugation in sucrose, was greater than 90% homogeneous. Conclusiom. The virus yields and purity were suitable for the study of virus-cell adsorption interactions. Recommendations: Further studies should be done using these techniques in an attempt to increase the amount of protein and virus applied to isopycnic and rate zonal gradients

VLT/SINFONI time-resolved spectroscopy of the central, luminous, H-rich WN stars of R136

Using the Very Large Telescope's Spectrograph for INtegral Field Observation in the Near-Infrared (VLT/SINFONI), we have obtained repeated AO-assisted, NIR spectroscopy of the six central luminous, Wolf-Rayet (WR) stars in the core of the very young (~1 Myr), massive and dense cluster R136, in the Large Magellanic Cloud (LMC). We also de-archived available images that were obtained with the Hubble Space Telescope's Space Telescope Imaging Spectrograph (HST/STIS), and extracted high-quality, differential photometry of our target stars to check for any variability related to binary motion. Previous studies, relying on spatially unresolved, integrated, optical spectroscopy, had reported that one of these stars was likely to be a 4.377-day binary. Our study set out to identify the culprit and any other short-period system among our targets. However, none displays significant photometric variability, and only one star, BAT99-112 (R136c), located on the outer fringe of R136, displays a marginal variability in its radial velocities; we tentatively report an 8.2-day period. The binary status of BAT99-112 is supported by the fact that it is one of the brightest X-ray sources among all known WR stars in the LMC, consistent with it being a colliding-wind system. Follow-up observations have been proposed to confirm the orbital period of this potentially very massive system.Comment: 9 pages, 6 figures; accepted for publication in MNRA

Non-linear MPC for winding loss optimised torque control of anisotropic PMSM

For a non-linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross-coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look-up-tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller

Non-linear MPC for winding loss optimised torque control of anisotropic PMSM

For a non-linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross-coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look-up-tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller

Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection

Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 mas remain mostly unknown due to intrinsic observational limitations. [...] The Southern MAssive Stars at High angular resolution survey (SMASH+) was designed to fill this gap by providing the first systematic interferometric survey of Galactic massive stars. We observed 117 O-type stars with VLTI/PIONIER and 162 O-type stars with NACO/SAM, respectively probing the separation ranges 1-45 and 30-250mas and brightness contrasts of Delta H < 4 and Delta H < 5. Taking advantage of NACO's field-of-view, we further uniformly searched for visual companions in an 8''-radius down to Delta H = 8. This paper describes the observations and data analysis, reports the discovery of almost 200 new companions in the separation range from 1mas to 8'' and presents the catalog of detections, including the first resolved measurements of over a dozen known long-period spectroscopic binaries. Excluding known runaway stars for which no companions are detected, 96 objects in our main sample (DEC < 0 deg; H<7.5) were observed both with PIONIER and NACO/SAM. The fraction of these stars with at least one resolved companion within 200mas is 0.53. Accounting for known but unresolved spectroscopic or eclipsing companions, the multiplicity fraction at separation < 8'' increases to f_m = 0.91 +/- 0.03. The fraction of luminosity class V stars that have a bound companion reaches 100% at 30mas while their average number of physically connected companions within 8'' is f_c = 2.2 +/- 0.3. This demonstrates that massive stars form nearly exclusively in multiple systems. Additionally, the nine non-thermal (NT) radio emitters observed by SMASH+ are all resolved [...]Comment: 57 pages, 20 figures, 7 tables; accepted for publication in ApJ

Exploring leadership communication in the United Arab Emirates: Issues of culture and gender

This study aims to identify what makes a successful leader in the UAE within the paradigms of leadership styles and leadership communication. In order to do this, we explore, and potentially challenge, a number of the existing leadership stereotypes that are germane to the region, along with the stereotypical discourse strategies that have been associated with the ways in which men and women enact leadership. We wanted to find out if Emirati nationals would prefer the type of discursive leadership that has been associated with women leaders, that is transformational leadership and collaborative communication, or if they would prefer the discursive leadership that has been stereotypically associated with men in equivalent positions, that is laissez-faire, transactional or paternalisticleadership styles, together with the use of a direct and competitive style of communication. Our findings show that a Western understanding of leadership may be too strictly delineated to account for leadership styles in the Gulf, and also that leaders in the region may effectively draw on a combined set of communication strategies that have been stereotypically attributed elsewhere to male and female leaders

Capacity of Gaussian MIMO Bidirectional Broadcast Channels

We consider the broadcast phase of a three-node network, where a relay node establishes a bidirectional communication between two nodes using a spectrally efficient two-phase decode-and-forward protocol. In the first phase the two nodes transmit their messages to the relay node. Then the relay node decodes the messages and broadcasts a re-encoded composition of them in the second phase. We consider Gaussian MIMO channels and determine the capacity region for the second phase which we call the Gaussian MIMO bidirectional broadcast channel.Comment: Proc. IEEE International Symposium on Information Theory (ISIT 2008), Toronto, Canada, July 200