• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 2
  • Tagged with
  • 5
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The influence of added mass on the natural vibrations and impulse response of long, thin cylindrical shells

Palmer, Edward Wilkerson January 1970 (has links)
The plane strain solution is obtained for the natural vibrations and impulse response of a thin circular cylinder containing an added line mass. The solution for a uniform cylinder is derived by taking the added mass to be zero. Numerical calculations of the frequencies and mode shapes for several of the lower modes are presented in graphical form for various values of the added mass. The general impulse response solution for arbitrary initial conditions is obtained by normal mode theory. For both the natural vibrations and impulse response, the theory is found to be in reasonable agreement with available experimental results. In a particular mode, four distinct solution states are found to exist: a symmetrical and anti-symmetrical branch for each class of vibration, flexural and extensional. Noteworthy features revealed by this investigation are the difference in frequency and mode shape of each solution state and the presence of coupling between the flexural and extensional classes, particularly noticeable in the extensional class mode shapes. In comparing impulse response solutions for velocity with and without the added mass, the major influence of the added mass is found to be an increased participation of the flexural class modes, including the rigid body translation, and decreased participation of the extensional class oscillatory modes. / Ph. D.
2

Stock price as an indicator of performance

Parcell, David Carson January 1970 (has links)
What significance can be attached to changes in the level of common stock prices? Ceteris paribus we usually assume that common stock prices are an external reflection of the performance of the firm in comparison with its profitability and growth.¹ This notion is generally referred to as the Baumol Hypothesis. The fact remains, however, that the usefulness of this hypothesis rests upon its ability to explain and predict stock price changes. In other words, it must be possible to discern a statistically significant relationship between the variables which reflect the activity of the firm (i.e., internal measures of performance) and the price of its stock (i.e., external measure of performance). This paper reports the results of an extended study of the relationship between stock price and the internal measures of firm performance. It employs annual financial data (over the period 1948-1966) for 99 of the 200 largest manufacturing corporations. The individual company stock price index used was computed from a monthly company stock price series. This base series contains the market price and the number of shares outstanding of each issue on the last Friday of each month. The other financial data was gathered from Moody's Industrials. Using this data, a series of simple regressions was computed to test for any significant relationship between stock prices and the selected measures of performance. The results were analyzed by cross~section analysis and by two- and three-digit industry analysis. It was found that assets, sales, net worth and profits all exhibit consistently significant and high r² values, whereas the profit ratios are much less important in explaining stock price variations. / Master of Arts
3

Investigation of Interactions of the Rubella Virus P150 Replicase Protein with Host Cell Proteins in Infected Cells

Suppiah, Suganthi 15 April 2009 (has links)
Due to their simplicity, viruses require the assistance of host factors for various aspects of their replication cycle. This study investigated the interaction of one of the two non-structural replicase proteins of rubella virus (RUBV), P150, with cell proteins. RUBV forms replication complexes for replicating its RNA in association with membranes of endosomes and lysosomes; the thusly modified endosomes/lysosomes are termed cytopathic vacuoles or CPVs. In the first study, a RUBV expressing a FLAG epitope-tagged P150 was used to co-immunoprecipitate putative interacting cell proteins from an infected cell lysate fraction enriched for CPVs using differential centrifugation. However, the only interacting protein identified was the companion RUBV replicase protein P90. Thus, cell proteins do not bind with either sufficient affinity or in stoichiometric amounts to be detected by this method and may not be a component of the virus holoenzyme. In the second study, a proline-rich region within P150 with three PxxPxR consensus SH3 domain-binding motifs was investigated for its ability to bind cell proteins. Substitution mutations (to alanine) of the two prolines were made in each of these motifs with the finding that mutations in the first two motifs led to lower viral titers and a small plaque phenotype with reversion to the wt sequence within one passage. Mutations in the third motif had a wt phenotype and did not revert. However, these mutations did not affect viral RNA synthesis, suggesting that the importance of these motifs is in a later stage of viral life cycle, e.g. virion assembly and release. To extend these findings, the proline hinge region with either the wt or mutant sequence was expressed as a GST-fusion in human cells. Pulldown experiments revealed specific binding with human p32 protein (gC1qR), which was previously shown to interact with the RUBV capsid protein. Binding of p32 with P150 was confirmed. The function of p32 in the RUBV replication cycle is unclear, but could involve virion assembly and release or induction of apoptosis.
4

Functional Characterization of the Cellular Protein p32 : A Protein Regulating Adenovirus Transcription and Splicing Through Targeting of Phosphorylation

Öhrmalm, Christina January 2006 (has links)
<p>Cellular processes involved in the conversion of the genetic information from DNA into a protein are often regulated by reversible phosphorylation reactions. By modulating the phosphorylated status of key proteins their activity can either be enhanced or repressed. In this thesis I have studied the significance of phosphorylation in the regulation of transcription and splicing using human adenovirus as a model system.</p><p>The results show that the activity of the cellular SR family of splicing enhancer or repressor proteins are reduced in adenovirus infected nuclear extracts by a virus-induced hypophosphorylation. The viral E4-ORF4 was shown to induce SR protein dephosphorylation by recruiting the cellular protein phosphatase PP2A. The E4-ORF4/PP2A complex was shown to relieve the SR protein-mediated repression of late virus-specific splicing and further activate alternative splicing in transiently transfected cells. Collectively, these results showed that alternative splicing, like many other biological processes, is regulated by reversible protein phosphorylation.</p><p>Similarly, the cellular p32 protein was shown to cause hypophosphorylation of the SR protein ASF/SF2 resulting in a reduced RNA binding capacity of ASF/SF2. This change in ASF/SF2 RNA binding also had a drastic effect on the function of ASF/SF2 as a regulatory protein affecting splice site choice. The cellular p32 protein and the viral E4-ORF4 protein both target the same cellular splicing factor, ASF/SF2. However, they regulate splicing by different mechanisms. E4-ORF4 recruits a phosphatase to dephosphorylate ASF/SF2, while p32 sequester ASF/SF2 in an inactive complex.</p><p>Further, we demonstrated that overexpression of p32 during a lytic infection suppressed transcription from the adenovirus major late transcription unit. p32 induced a selective repression of CAAT-box containing promoters indicating the involvement of the transcription factor CBF/NF-Y in this regulation. A further analysis showed that p32 caused a hyperphosphorylation of the CTD of RNA Pol II, which resulted in a significant reduction in the processivity of Pol II during the elongation phase of transcription.</p><p>In summary, we have shown that E4-ORF4 regulates the activity of splicing regulatory SR proteins, and that p32 regulates the activity of the SR protein ASF/SF2 in splicing and Pol II processivity during transcription elongation. Mechanistically, both E4-ORF4 and p32 appears to function by regulating the phosphorylated status of key cellular proteins involved in these processes.</p>
5

Functional Characterization of the Cellular Protein p32 : A Protein Regulating Adenovirus Transcription and Splicing Through Targeting of Phosphorylation

Öhrmalm, Christina January 2006 (has links)
Cellular processes involved in the conversion of the genetic information from DNA into a protein are often regulated by reversible phosphorylation reactions. By modulating the phosphorylated status of key proteins their activity can either be enhanced or repressed. In this thesis I have studied the significance of phosphorylation in the regulation of transcription and splicing using human adenovirus as a model system. The results show that the activity of the cellular SR family of splicing enhancer or repressor proteins are reduced in adenovirus infected nuclear extracts by a virus-induced hypophosphorylation. The viral E4-ORF4 was shown to induce SR protein dephosphorylation by recruiting the cellular protein phosphatase PP2A. The E4-ORF4/PP2A complex was shown to relieve the SR protein-mediated repression of late virus-specific splicing and further activate alternative splicing in transiently transfected cells. Collectively, these results showed that alternative splicing, like many other biological processes, is regulated by reversible protein phosphorylation. Similarly, the cellular p32 protein was shown to cause hypophosphorylation of the SR protein ASF/SF2 resulting in a reduced RNA binding capacity of ASF/SF2. This change in ASF/SF2 RNA binding also had a drastic effect on the function of ASF/SF2 as a regulatory protein affecting splice site choice. The cellular p32 protein and the viral E4-ORF4 protein both target the same cellular splicing factor, ASF/SF2. However, they regulate splicing by different mechanisms. E4-ORF4 recruits a phosphatase to dephosphorylate ASF/SF2, while p32 sequester ASF/SF2 in an inactive complex. Further, we demonstrated that overexpression of p32 during a lytic infection suppressed transcription from the adenovirus major late transcription unit. p32 induced a selective repression of CAAT-box containing promoters indicating the involvement of the transcription factor CBF/NF-Y in this regulation. A further analysis showed that p32 caused a hyperphosphorylation of the CTD of RNA Pol II, which resulted in a significant reduction in the processivity of Pol II during the elongation phase of transcription. In summary, we have shown that E4-ORF4 regulates the activity of splicing regulatory SR proteins, and that p32 regulates the activity of the SR protein ASF/SF2 in splicing and Pol II processivity during transcription elongation. Mechanistically, both E4-ORF4 and p32 appears to function by regulating the phosphorylated status of key cellular proteins involved in these processes.

Page generated in 0.0625 seconds