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  • 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.
641

The Ball State University Directed Admission Student Experimental Program, 1968-1972

Foster, Robert Oscel 03 June 2011 (has links)
During the summer of 1968, the Vice President for Student Affairs at Ball State University, established the Office of Special Programs. Personnel of the Office were charged with the responsibility for developing and providing special services for students with low academic records so that collegiate success and persistence might be enhanced. The Director of Special Programs was directly charged with the responsibility for providing academic counseling, advice relative to course selections, and for marshalling existing university academic and ancillary support systems as necessary to improve college persistence behaviors among students classified for "Admission with Warning."Personnel of the Office of Special Programs developed and implemented a program designed to provide special academic and supportive services to "Admission with Warning" students. The Directed Admission Student Experimental Program was implemented in the fall of 1968. The program included a remedial reading course, a remedial writing course designed specifically for students identified for the DASEP experience. Personal counseling and special Curricular Advising services were provided to all DASEP students. Over the period from 1968-1972 a total of 274 students were selected to be participants in the DASEP group, and a total of 273 students were identified for inclusion in a control group.The purpose of this study was to determine whether students admitted to the Ball State University Directed Admission Student Experimental Program (DASEP) during the period from 1968 to 1972, persisted to program completion more frequently than did similar students in an identical non-DASEP control group. If the null hypothesis relating to the major purpose was not accepted, differences among DASEP persisters and non-persisters would be investigated.A second purpose of the study was to collect and analyze evaluative perceptions from participants of the Directed Admission Student. Experimental Program relative to the special services provided.The research was planned to test the null hypothesis relating to persistence in the DASEP program and to secure evaluative perceptions about the services from 274 DASEP students.The investigator collected data on persistence in the DASEP program from 265 DASEP and 255 control group students. Data were statistically treated by means of the chi square statistic. The .05 level was used for hypothesis acceptance or non-acceptance. In order to secure evaluative perceptions about services provided participants in the DASEP program, a Likert type instrument was developed and sent to 250 participants in the DASEP program. Review of the data led to the following conclusions:There was no statistically significant difference found between the DASEP group and control group students in persistence to the completion of their individual educational program.Less than one-half of the DASEP students perceived the services provided by the Reading Clinic to be helpful.Slightly more than one-half perceived the services of the Writing Clinic to be helpful.Depending upon the service, about one-half of the students perceived the special Curricular Advising services to be helpful.About one-third perceived the subjects taught in the seminar class to be helpful.Slightly less than one-half of the DASEP students perceived counseling, provided by the staff of Special Programs to be helpful.In a summary question, 94 percent of the DASEP students perceived the DASEP program had been beneficial to them.
642

Structure and Dynamics of AcrA, a Periplasmic Component of a Multidrug Efflux Pump

Ip, Hermia 18 February 2010 (has links)
AcrA is the periplasmic component of an efflux system AcrA-AcrB-TolC, which can expel different classes of antibiotics. AcrB is the inner membrane (IM) pump that utilizes proton-motive force for the active transport, TolC is the outer membrane (OM) channel, and AcrA coordinates the actions of AcrB and TolC, so that substrates are expelled across the two membranes, bypassing the periplasm. It has been proposed that AcrA either provides a static seamless link between AcrB and TolC, or acts like its analogous viral membrane fusion protein (MFP) and actively brings the IM and OM closer for substrate transfer. To better understand the role of AcrA in the efflux mechanism, site-directed spin labeling (SDSL)/EPR (electron paramagnetic resonance) spectroscopy is used to investigate the structure and dynamics of AcrA in solution. My results demonstrated that AcrA is a dynamic protein that undergoes pH-dependent and reversible conformational changes. AcrA contains an interrupted alpha-helical, coiled-coil domain flanked by a pair of beta-stranded lipoyl motifs, and my SDSL/EPR analysis revealed that the pH-induced conformation change mainly involves the coiled-coil and the lipoyl domains. In addition, I found that each AcrA monomer folds into an intra-molecular hairpin and AcrA monomers oligomerize with their coiled-coil hairpins aligned in parallel. Unlike the pH-induced conformational rearrangement of a viral MFP, change in pH alters both intra- and inter-molecular interaction along the coiled-coil of AcrA without rearranging the hairpin fold. The organization of AcrA protomers and its pH-induced conformational switching are, however, congruent with the TolC coiled-coil hairpins in the iris-like opening of the TolC channel. Together, my studies suggest that rather than being a passive structural linkage between AcrB and TolC, AcrA plays an active role mediating the drug efflux. The reported AcrA dynamics provides new insights into the AcrA-TolC interactions for the channel opening during the efflux process.
643

Essays on Macroeconomics and Political Economy

Ge, Jinfeng January 2012 (has links)
This thesis consists of three self-contained essays dealing with different aspects of macroeconomics and political Economy. The Relative Price of Investment Goods and Sectoral Contract Dependence I develop a quantitative model to explain the relationship between TFPs at the aggregate and sector levels and contracting institutions across countries. The incomplete contract enforcement induces distortions in the production process which come from the “hold up” problem between a final goods firm and its suppliers. Because investment goods sector is more contract dependent, its productivity suffers more from the distortion. In turn, countries endowed with weaker contract enforcement institutions face higher relative prices of investment goods. A Ricardian Model of the Labor Market with Directed Search I analyze how search friction affects the allocation in a Ricardian model of the labor market. The equilibrium shows that the matching pattern is partially mixed: Some tasks are only performed by skilled workers; some are only performed by unskilled workers; the remaining tasks are performed by both skilled and unskilled workers. The mixed matching pattern implies a mismatch in equilibrium. It turns out that the reason for the mismatch has its roots in search friction. In addition, I show labor market institutions have interesting implications for the unemployment rate and mismatch. A Dynamic Analysis of the Free-rider Problem I argue that special interest groups overcome their free-rider problem thanks to distorted government policy. As policy confers monopoly privileges on a group, it can also preserve and promote group’s organization. The key to sustaining the organization of the group is a dynamic incentive: when distorted policy generates rents for a group, each member of the group wish to make contributions not just to raise their rents today; they want to sustain their cooperation so that they will be able to influence policy in the future.
644

Managing Dependencies in Knowledge-Based Systems: A Graph-Based Approach

Tapankov, Martin January 2009 (has links)
In knowledge-based engineering, the inference engine plays an important part in the behaviour of the system. A flexible and adaptive execution scheme allows the designer to experiment with different modes of operation and selecting an appropriate one with respect to the initial data set and the execution goal. In this project, an extension of an existing research prototype software in the field of knowledge-based engineering will be developed, with the goal of building a reliable and easy to use dependency resolution engine that will replace a less-than-ideal current implementation of the same. A discussion will be included how the knowledge concepts and objects can be represented in an abstract mathematical form, converting at the same time the problem of dependency resolution to a more formally specified one in terms of the data abstraction proposed. Some algorithms and methods that are used to operate on the data set will be discussed from both a theoretical and programming point of view, analysing their complexity, proposing and testing their implementation. Graphical interface controls that can be used to visualize and understand easily the relations in the available knowledge base will be also demonstrated. The testing and verification of the resulting software will be presented, comparing its behaviour against reference tools serving similar purposes. Methods for validating the consistency of the knowledge base will also be discussed. Finally, the integration of the newly-developed code within the context of the prototype will be discussed, commenting on the new features and functionality gained.
645

Investigation of the interactions between the bacterial homologue to actin, and the chaperone GroEL/ES through a combination of protein engineering and spectroscopy / Undersökning av interaktionerna mellan MreB, den bakteriella homologen till aktin, och chaperonet GroEL/ES genom en kombination av protein engineering och spektroskopi

Blom, Lillemor January 2008 (has links)
Molecular chaperones help many proteins in the cell reach their native conformation. The mechanism with which they do this has been studied extensively, but has not been entirely elucidated. This work is a continuation of the study done by Laila Villebeck et al. (2007) on the conformational rearrangements in the eukaryotic protein actin in interaction with the eukaryotic chaperone TRiC. In this study the intentions were to analyze the protein MreB, a prokaryotic homologue to actin, when interacting with the prokaryotic chaperone GroEL. The purpose was to investigate if the mechanisms of GroEL and TRiC are similar. The analysis of the conformation of MreB was to be made through calculations of fluorescence resonance energy transfer (FRET) between two positions in MreB labeled with fluorescein. A MreB mutant was made through site-specific mutagenesis to enable labeling at a specific position. Another single mutant and a corresponding double mutant needed for these measurements were avaliable from earlier studies. The results from fluorescence measurements on these mutants indicated that the degree of labeling was insufficient for accurate determination of FRET. Suggestions are made on improvements of the experimental approach for future studies.
646

Modeling of transient protein-protein interactions: a structural study of the thioredoxin system

Obiero, Josiah Maina 25 February 2011 (has links)
ABSTRACT Protein-protein interactions play a central role in most biological processes. One such biological process is the maintenance of a reducing environment inside the cell. To maintain an internal reducing environment, living cells have evolved two enzymatic systems (glutathione and thioredoxin (Trx) systems). The Trx system is composed of the enzyme TrxR and its substrate Trx. The two proteins constitute an important thiol-dependent redox system that catalyzes the reduction of many proteins that are responsible for a variety of cellular functions. The system relies on transient protein-protein interactions between Trx and TrxR for its function. Cross-reactivity of components of the Trx system between species has been shown to be medically relevant. For example, Helicobacter pylori Trx (HP Trx) is thought to mediate catalytic reduction of human immunoglobulins and thus facilitate immune evasion. It has also been proposed that Helicobacter pylori gains access to the impenetrable gastric mucous layer by using secreted HP Trx to reduce the disulfide bonds present in the cysteine-rich mucin regions that are responsible for cross-linking mucin monomers. Therefore, disruption of secreted HP Trx-host protein interaction may result in restoration of the viscoelastic and hydrophobic protective properties of mucus. Previous studies aimed at understanding the nature of cross-reactivity of Trx system components among various species have shown that Trxs have higher affinity for cognate TrxRs (same species), than for TrxRs from different species. However, the basis for this specificity is not known. A growing body of evidence suggests that most protein-protein interactions are mediated by a small number of protein-protein interface residues, referred to as hot spot residues or binding epitopes. Therefore, understanding the biochemical basis of the affinity of proteins for their partners usually begins by identifying the hot spot residues responsible for the protein complex interactions. In this study, the crystal structures of Deinococcus radiodurans thioredoxin reductase (DR TrxR) and Helicobacter pylori TrxR (HP TrxR) were determined at 1.9 Å and 2.4 Å respectively. Analysis of the Trx-binding sites of both structures suggests that the basis of affinity and specificity of Trx for TrxR is primarily due to the shape rather than the charge of the surface. In addition, the complex between Escherichia coli thioredoxin reductase (EC TrxR) and its substrate thioredoxin (EC Trx) was used to identify residues that are responsible for TrxR-Trx interface stability. Using computational alanine scanning mutagenesis and visual inspection of the EC TrxR-Trx interface, 22 EC TrxR side chains were shown to make contact across the TrxR-Trx interface. Although more than 20 EC TrxR side chains make contact across the TrxR-Trx interface, our results suggest that only 4 residues (F81, R130, F141, and F142) account for the majority of the EC TrxR-Trx interface stability. Individual replacement of equivalent DR TrxR residues (M84, K137, F148, F149) with alanine resulted in drastic changes in binding affinity, confirming that the four residues account for most of TrxR-Trx interface stability. These hot spot residues are surrounded by less important residues (hydrophobic and hydrophilic) that are also predicted to contribute to interface stability. F148 and F149 are invariant across bacterial TrxRs, however other residues that contact Trx are less conserved including M84 and K137. When M84 and K137 were changed to match equivalent E. coli TrxR residues (K137R, M84F); D. radiodurans TrxR substrate specificity was altered from its own Trx to that of E. coli Trx. The results suggest that a small subset of the TrxR-Trx interface residues are responsible for the majority of Trx binding affinity and specificity, a property that has been shown to general to protein-protein interfaces.
647

Äldreriktat tal på boenden för äldre : Förekomst och karaktäristik / Elderspeak in Geriatric Institutions : Occurrence and Characteristics

Adolfsson, Elin, Persson, Hanna January 2011 (has links)
Äldreriktat tal avser kommunikationsanpassningar gentemot äldre liknande de som görs till små barn. Anpassningarna sker inom flera språkliga domäner och är en del av äldres kommunikativa miljö. Ämnet är relativt outforskat och få eller inga studier har gjorts i Sverige. Föreliggande studies syfte var att undersöka eventuell förekomst av äldreriktat tal, samt beskriva dess karakteristika då personal på olika typer av boenden för äldre samtalar med en äldre. Deltagare är fem personer som arbetar på olika former av boenden för äldre. Samtal mellan personal och äldre samt samtal mellan personal och en kollega spelades in och grovtranskriberades. Inspelningarna klipptes till filer utifrån varje analys syfte. Arbetet antog en datadriven ansats och data studerades utifrån tidigare forskning kring äldreriktat och barnriktat tal. I föreliggande studie påvisades att deltagande personal på boende för äldre, i varierande grad, anpassade sin kommunikation inom flera språkliga domäner. Anpassningarna förekom huvudsakligen inom den prosodiska domänen men förekom i viss utsträckning även inom den grammatiska. Anpassningar inom den pragmatiska domänen påvisades till viss del medan anpassningar inom den semantiska domänen ej förekom. Tendenser till talanpassningar förekom hos majoriteten av deltagarna. Följande tillägg av delaspekter till äldreriktat tal föreslås; upprepat användande av namn, mindre samtidigt tal och färre tvekfenomen. / The term elderspeak refers to the adjustments of communication towards elderly people which are similar to those made towards young children. The adjustments are made within several language domains, and are a part of the communicative environment of the elders. The subject is relatively uninvestigated, and few, if any, studies have been conducted on the subject in Sweden. Thus the aim of the present study was to investigate the possible occurrence of elderspeak, and to describe its characteristics. The present study is based upon five participants working at different forms of geriatric institutions. Conversations between a caregiver and a resident and conversations between a caregiver and a colleague were recorded and broadly transcribed. The recordings were cut into separate files according to the purpose of respective analysis. The study was carried out with a data-driven perspective and previously established aspects of elderspeak and child directed speech was searched for. The present study established that caregivers to a varying extent adjusted their communication within several language domains. The adjustments mainly took place within the prosodic domain but they also took place within the grammatical domain. Adjustments within the pragmatic domain were found to some extent, but no adjustments within the semantic domain were found. Tendencies to adjustments of the speech were present in the majority of the participants. The present study suggests the following additions to the aspects of the elderspeak phenomenon; frequent use of name, less hesitation phenomena and less frequent simultaneous speech.
648

Three essays on monetary policy, the financial market, and economic growth in the U.S. and China

Yang, Juan 15 May 2009 (has links)
Does monetary policy affect the real economy? If so, what is the transmission mechanism or channel through which these effects occur? These two questions are among the most important and controversial in macroeconomics. This dissertation presents some new empirical evidence that addresses each question for the U.S. and Chinese economies. Literature on monetary transmission suggests that the monetary policy can take effect on the real economy through several ways. The most noteworthy one is credit channels, including the bank lending channel and the interest channel. First, I use a new method to test for structural breaks in the U.S. monetary policy history and present some new empirical evidence to support an operative bank lending channel in the transmission mechanism of monetary policy. Results show that an operative bank lending channel existed in 1955 to 1968, and its impact on the economy has become much smaller since 1981, but it still has a significant buffering effect on output by attenuating the effect of the interest channel. Second, I adopt the recently developed time series technique to explore the puzzling negative correlation between output and stock returns in China currently, and posit that it is due to a negative link between monetary policy and stock returns when monetary policy increases output. The monetary policy has not been transmitted well in the public sector which is the principal part of Chinese stock market, and increased investment capital from monetary expansion goes to real estate sector instead of the stock market. Last, I demonstrate how monetary policy has been transmitted into the public and private sectors of China through the credit channel. The fundamental identification problem inherent in using aggregated data that leads to failure in isolating demand shock from supply shock is explicitly solved by introducing control factors. I find that the monetary policy has great impact on private sector rather than public sector through credit channel in China. These findings have important practical implications for U.S. and China’s economic development by improving the efficiency of the monetary policy because a comprehensive understanding of monetary transmission will lead to better policy design.
649

Adult education, popular culture, and women's identity development: self-directed learning with The Avengers

Wright, Robin Redmon 02 June 2009 (has links)
The purpose of this study was to investigate the impact of popular culture, especially prime-time television, on women learner-viewers’ identity development. More specifically, this study explores one specific television show, the 1962-64 Cathy Gale episodes of The Avengers as a portal to adult learning. It further explores the ways in which television, as a form of public pedagogy, can help facilitate the formation of a critical or feminist identity among adult learner viewers. The research questions guiding this study were: 1) How and what did women learn from watching The Avengers? 2) How did women incorporate that learning into their lives and into their identities? and 3) How did women interpret and accommodate the feminist example of Cathy Gale? Data for this study was collected over a two-and-a-half year period. Data consisted of interviews with contemporaneous viewers of the Cathy Gale Avengers episodes, interviews with scriptwriters and the actor who played Cathy Gale, Honor Blackman, numerous documents from statistics obtained at the British Film Institute, fanzines, and newspaper articles of the period. Analysis revealed that in particular historical times and situations television viewing can become a form of public pedagogy, facilitating transformational learning in adult viewers that produces lasting, life-changing effects. The investigation revealed that not only did biologically-born women incorporate Cathy Gale’s feminist example into their identities and actions, but biologically born males whose core gender identity was female did also. This dissertation is written in article format. Each of the six sections has been designed as stand-alone pieces to aid accessibility and enhance readers’ engagement with the study.
650

The Effect of Practice on Learning and Transferring Goal Directed Isometric Contractions across Ipsilateral Upper and Lower Limbs

Kaur, Navneet 2009 May 1900 (has links)
The purpose of this thesis was to determine whether practice-induced adjustments and retention of a goal directed isometric motor accuracy task were similar between ipsilateral upper and lower limb and whether there is an ipsilateral transfer between upper and lower limbs. In addition, this thesis project aimed to determine whether motor output variability and the activity of the involved agonist and antagonist muscles could predict any of the above stated changes. Sixteen young adults (8 men, 8 women; 22.1 or - 2.1 years) performed 80 trials of goal directed isometric contractions that involved accurately matching a target force of 25% MVC in 200 ms, either with the upper limb or the lower limb followed by the other limb. After an interval of 48 hours, 10 trials similar to the practice trials were performed to examine retention. Feedback of performance was provided in the form of a force-time trajectory along with numerical error values for force and time on each trial. End-point error was quantified as the absolute deviation from the targeted force and time. Motor output variability was quantified as the SD of force, SD of time to peak force and SD of force trajectory. The practice-induced adjustments for force and time endpoint accuracy were similar for the two limbs, however, two days later, retention of the force accuracy was better with the upper limb compared with the lower limb. Practice-induced reduction and practice-to-retention increase in force and time endpoint error were predicted by respective changes in peak force and time to peak force trial-to-trial variability for both limbs. In addition, the changes in accuracy were predicted by the changes in the activity of the involved agonist and antagonist muscles. Nonetheless, the changes in muscle activity differed between the two limbs. The adjustments in muscle activity were also different during the practice session despite the fact that the rate of improvement was similar for the two limbs. Finally, there was an asymmetric transfer of force accuracy from the lower limb to the ipsilateral upper limb, which was associated with the changes in motor output variability. The upper limb, which is inherently less variable as compared to the lower limb, may have retained the task better due to the formation of a stronger muscle synergy (or stronger internal model) to perform the contractions with accuracy. The lower limb, on the other hand may have formed a weaker internal model due to the greater interference from amplified signal-dependent noise (motor output variability) or an alternative motor plan, which may have been concerned primarily with the minimization of motor output variability instead of formation of a muscle synergy to perform the contractions accurately.

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