Ribosomes translate the genetic information encoded by mRNA into proteins. Defective mRNAs can cause stalling of translating ribosomes. The molecule tmRNA (transfer-messenger RNA) rescues stalled ribosomes in eubacteria. Together with its protein partner SmpB, tmRNA mimics a tRNA by entering the ribosomal A site and linking an alanine residue to the growing polypeptide chain. The ribosome then abandons the defective mRNA template and resumes translation on tmRNA, adding ten more amino acids to the nascent polypeptide. As a result of tmRNA action, stalled ribosomes are released and recycled, the defective mRNA is destroyed, and the aborted protein product is tagged for destruction by proteases. It is unknown how the ribosome correctly chooses the position on tmRNA to resume translation. Previous studies implicate the sequence UAGUC found immediately upstream of the first codon in the tmRNA open reading frame. These nucleotides are highly conserved in natural tmRNA sequences. Mutations in this area cause loss of tmRNA function and improper frame choice. Using a genetic selection that ties the life of E. coli cells to the function of tmRNA, we have identified several SmpB mutants that rescue an inactive tmRNA in which this upstream sequence was altered. This links SmpB to the function of these key tmRNA nucleotides. We show that our SmpB mutants affect frame choice using an in vivo assay for tagging in the various frames. We conclude that SmpB plays a role in setting the reading frame on tmRNA.

This paper describes the investigation of a mill building bent of truss and column design, a redesign using a rigid-frame, and an estimated cost of each design. For sake of brevity the overall design of the building (sway bracing, lateral bracing, purlins, girts, roofing, siding, and bay spacing) was assumed to be the same for both designs. It is possible that this assumption cannot be made and the estimates of cost, therefore, are in error. In actual practice the complete redesign of the building should be considered.

This project’s goals are to evaluate the structure and strength design of Schnadig three-seat sofa frames, summarize current available information on engineering design, derive cyclic schedules for durability evaluation of frame components, and improve the design to meet product performance requirement specified by Schnadig. The target goal of medium or above acceptance level of General Service Administration (GSA) performance test was expected for the improved design. The design procedures and testing results in the study are also applicable to other frames, and can be used as a guideline for product engineering and reengineering. In this study, the mechanical and strength properties of frames, and members and joints, were evaluated. Schnadig three-seat sofa frames were evaluated by the performance tests. Six sets of tests were conducted with three replicates for each test. The critical joints and members were identified. Generally the frames did not reach the anticipated medium acceptance level except for the arm vertical test, where all the tested frames passed heavy duty. The inadequate connection of joints and the weak member were the major cause of failure. Next, the static and fatigue properties of selected plywood, oriented strand board (OSB) and particle board (PB) were investigated. The regression equations of S-N (stress versus number of cycles to failure) through low 5% points (i.e., the 5th percentile) were derived for all selected wood composite materials and proposed as design equations for achieving a conservative design of furniture frame structural members considering fatigue effects. It was found that the fitting constant E in the S-N equation at low 5% data was 0.85, and the constant H values were 0.06, 0.08, and 0.10, for plywood, OSB, and PB, respectively. Analysis results indicted that when cyclic stepped load effects were considered, the allowable design stress for plywood, OSB, and PB should not exceed respectively, 54%, 64%, and 68% of their MOR. Experiments were also designed to investigate the lateral shear and direct withdraw load resistances of face-toace and end-toace joints. Two types of connection, glue and single staple, were studied. Load direction relative to grain direction was considered. Statistical analyses were implemented to study the effect on the load resistance of the joints. Lastly, a solid 3D frame model was developed in I-DEAS to obtain the internal forces on critical components. Suggestions on the constructions of critical components were made based on internal forces obtained from computer modeling, as well as the laboratory results of frames, members, joints. One result of this study is the recommendations for improved construction details.

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Light-frame wood construction is frequently used in the U.S. High wind events, such as hurricanes, may cause severe damage to these structures by breaking the roof envelope. This study focuses on computing reliability indices of roof sheathing panels exposed to high wind events while considering a time and spatially varying wind load. A procedure is developed that links probabilistic and dynamic finite element analysis codes. The results show that a few critical panels are most susceptible to damage, while most panels have significantly higher reliability indices than previous studies based on simplified analyses have shown. By setting a target reliability index, panel nail spacing can be adjusted to provide a more uniform level of safety over the entire roof.

This research investigates the application of multiuser interference suppression to direct-sequence code-division multiple-access (DS-CDMA) for peer-to-peer packet radio networks. The emphasis of this work is to develop and validate efficient interference suppression techniques through selective cancellation of interference; next, the combination of interference suppression with error correction coding is studied. A decoder-assisted frame synchronization technique is proposed for future packet radio system. The performance of DS-CDMA in packet radio networks suffers from the near-far problem. This near-far problem can be alleviated by using either a multiuser receiver or a single-user adaptive receiver along with centralized or distributed power control. The first part of this dissertation compares the use of these receivers in a peer-to-peer environment. Next, we investigate how interference cancellation can be combined with forward error correction coding for throughput enhancement of the system. Although receivers using interference suppression are simple in structure, the performance degrades due to the lack of exact knowledge of the interfering signal in cancellation and also due to biased decision statistics for the parallel cancellation case. We consider a system that employs both partial parallel interference cancellation and convolutional coding. Information is shared between the operations of interference cancellation and decoding in an iterative manner, using log-likelihood ratios of the estimated coded symbols. We investigate the performance of this system for both synchronous and asynchronous CDMA systems, and for both equal and unequal signal powers. Finally, a new code-assisted frame synchronization scheme, which uses the soft-information of the decoder, is proposed and evaluated. The sync bits are placed in the mid-amble, and encoded as a part of the data sequence using the error correction encoder to resolve time ambiguities. This technique is applied for turbo decoder-assisted frame synchronization. The performance improvement of these proposed techniques over conventional synchronization techniques is explored via simulation. / Ph. D.

With the increased social attention to active shooting events in the United States, news outlets are featuring news briefs through social media platforms like Twitter. Using this method of information sharing, news organizations can instantly reach consumers as events unfold in real time. With character limitations with Twitter, one may assume news organizations use words carefully and succinctly to report vital information to the public. By implementing a content analysis of news organization Twitter contributions, messages provided by both legacy and digital native news outlets were evaluated. Using Department of Justice reports specifically covering active shooting events, 32 specific incidents covering the years of 2014-2018 were selected for analysis. This resulted in the identification of over 14,000 individual Tweets. These Tweets were then analyzed using a content analysis to identify overarching themes. Apparent from the onset was the clear priority of news organizations to report on the perpetrators of active shooting events while focusing noticeably less on the victims of these violent events. Further, policy advocation or calls to change current policy was noticeably absent from Twitter discussions. The focus of this paper is to explore the characteristics of emphasized by legacy and digital native news media outlets. This analysis has direct implications on the culture of gun violence, as well as market models which influence the news production process when reporting on active shooting incidents in the United States. / Doctor of Philosophy / Social media has increased in popularity in recent history. The incorporation of social media into a variety of topics, including reporting the news, has also increased. This aim of this study is to evaluate the types of contributions made by news media outlets on the social media platform Twitter. Specifically, this research is focused on Twitter contributions pertaining to active shooting events in the United States between 2014-2018. 32 active shooting events were identified over this period, which includes a collection of more than 14,000 Tweets by news outlets. Priorities of news media outlets were identified by analyzing the content of Tweets. Analysis revealed a significant portion of Tweets characterizing the offender's personal identity, background, and actions while providing sparse reporting on victims in these events. This research provides critical insight into how Twitter is used to report on criminal justice events. Additionally, this study illustrates the ways in which social media is being used to report the news, and how this may differ from traditional methods of news dissemination.

From Structure to Urban Frames In the context of this thesis, the notion of frame is recognized as enclosing borders, or the outline of views, rather than as a load-bearing structural element. This thesis investigates how frames can build urban connections and, at the same time, structure sequences of movement and define a path with a variety of spatial experiences. / Master of Architecture