6,317 research outputs found
Technology Acceptance and Use in a Knowledge Management Support System: An Exploratory Case Study of Air Force Knowledge Now Communities of Practice
Over the past five to seven years, the United States Air Force has begun to employ online Communities of Practice (CoP) as a means to collaborate virtually. During this time, there have been several studies of these online communities to better understand their use, as well as their lack of use. The primary goal of this research is to apply the theories of Davis\u27 (1989) technology acceptance model to identify the factors that affect the acceptance and use of CoPs. These findings are then used to provide suggestions on how to improve the acceptance and use of CoPs for CoP administrators and, ultimately, the Air Force Knowledge Now (AFKN), the managerial owners of all CoPs. This research used a mixed method strategy to collect data. Data were gathered from a previous research study on AFKN CoPs, a pre-interview survey, and an interview that included both open- and close-ended questions. This method allowed the researcher to converge on the broad results in order to focus on detailed views from the participants. The findings from this research suggest differences in users\u27 perceptions based on functional makeup, formality, access, length of use, and user\u27s grade/position. In addition, the factors of social influence, facilitating conditions, and user acceptance enablers strongly influenced the usage behavior of CoP users. Finally, the interview process exposed numerous factors that encouraged and discouraged use of the CoPs
The Effect of the Internet on the Advertising Industry in a Consumer Culture
A revolution is under way, possibly of the same magnitude as the 19th Century industrial revolution. The information age is upon us at an unparalleled rate of growth. The Internet spearheads the drive forward towards a world where knowledge that shapes our lives is truly common, affecting every culture on the planet. Commercial advertising is the science of disseminating information in a meaningful way and it is therefore relevant to wonder how this new-world order will affect both advertising and the underlying cultures. When will it happen? Who will it affect? What form will it take? How will it affect our national cultures and what benefits or disbenefits will follow? What will happen to the advertising industry? Where will the opportunities be? This study has aimed to answer these questions and to apply them to our underlying consumer culture, targeting the impact of the Internet on advertising and its’ direction
Counselors as Advocates: Effects of a Pilot Project Designed to Develop Advocacy Knowledge and Confidence in Trainees
While there has been increased attention to advocacy within counseling and counseling psychology, it has been noted that trainees generally feel unprepared to engage in advocacy and do not participant e in this type of work to a large extent, even with increased age or professional experience). The qualitative study summarizes the findings of a project within a graduate multicultural counseling course designed to increase trainee knowledge and confidence related to advocacy. This project required students (N = 19) to complete individual advocacy projects in the community, with opportunities for self-reflection and evaluation of their progress throughout the semester. Student reflection responses about the effects of this project were analyzed using methods from Grounded Theory by a collaborative research team. This process resulted in a core category of responses that included expanded definitions of advocacy, increased self-confidence regarding advocacy work, obstacles encountered, and reactions to the course assignment. Implications and future directions are discussed
Evidence from glycine transfer RNA of a frozen accident at the dawn of the genetic code
<p>Abstract</p> <p>Background</p> <p>Transfer RNA (tRNA) is the means by which the cell translates DNA sequence into protein according to the rules of the genetic code. A credible proposition is that tRNA was formed from the duplication of an RNA hairpin half the length of the contemporary tRNA molecule, with the point at which the hairpins were joined marked by the canonical intron insertion position found today within tRNA genes. If these hairpins possessed a 3'-CCA terminus with different combinations of stem nucleotides (the ancestral operational RNA code), specific aminoacylation and perhaps participation in some form of noncoded protein synthesis might have occurred. However, the identity of the first tRNA and the initial steps in the origin of the genetic code remain elusive.</p> <p>Results</p> <p>Here we show evidence that glycine tRNA was the first tRNA, as revealed by a vestigial imprint in the anticodon loop sequences of contemporary descendents. This provides a plausible mechanism for the missing first step in the origin of the genetic code. In 448 of 466 glycine tRNA gene sequences from bacteria, archaea and eukaryote cytoplasm analyzed, CCA occurs immediately upstream of the canonical intron insertion position, suggesting the first anticodon (NCC for glycine) has been captured from the 3'-terminal CCA of one of the interacting hairpins as a result of an ancestral ligation.</p> <p>Conclusion</p> <p>That this imprint (including the second and third nucleotides of the glycine tRNA anticodon) has been retained through billions of years of evolution suggests Crick's 'frozen accident' hypothesis has validity for at least this very first step at the dawn of the genetic code.</p> <p>Reviewers</p> <p>This article was reviewed by Dr Eugene V. Koonin, Dr Rob Knight and Dr David H Ardell.</p
The transition from noncoded to coded protein synthesis: did coding mRNAs arise from stability-enhancing binding partners to tRNA?
<p>Abstract</p> <p>Background</p> <p>Understanding the origin of protein synthesis has been notoriously difficult. We have taken as a starting premise Wolf and Koonin's view that "evolution of the translation system is envisaged to occur in a compartmentalized ensemble of replicating, co-selected RNA segments, i.e., in an RNA world containing ribozymes with versatile activities".</p> <p>Presentation of the hypothesis</p> <p>We propose that coded protein synthesis arose from a noncoded process in an RNA world as a natural consequence of the accumulation of a range of early tRNAs and their serendipitous RNA binding partners. We propose that, initially, RNA molecules with 3' CCA termini that could be aminoacylated by ribozymes, together with an ancestral peptidyl transferase ribozyme, produced small peptides with random or repetitive sequences. Our concept is that the first tRNA arose in this context from the ligation of two RNA hairpins and could be similarly aminoacylated at its 3' end to become a substrate for peptidyl transfer catalyzed by the ancestral ribozyme. Within this RNA world we hypothesize that proto-mRNAs appeared first simply as serendipitous binding partners, forming complementary base pair interactions with the anticodon loops of tRNA pairs. Initially this may have enhanced stability of the paired tRNA molecules so they were held together in close proximity, better positioning the 3' CCA termini for peptidyl transfer and enhancing the rate of peptide synthesis. If there were a selective advantage for the ensemble through the peptide products synthesized, it would provide a natural pathway for the evolution of a coding system with the expansion of a cohort of different tRNAs and their binding partners. The whole process could have occurred quite unremarkably for such a profound acquisition.</p> <p>Testing the hypothesis</p> <p>It should be possible to test the different parts of our model using the isolated contemporary 50S ribosomal subunit initially, and then with RNAs transcribed <it>in vitro </it>together with a minimal set of ribosomal proteins that are required today to support protein synthesis.</p> <p>Implications of the hypothesis</p> <p>This model proposes that genetic coding arose <it>de novo </it>from complementary base pair interactions between tRNAs and single-stranded RNAs present in the immediate environment.</p> <p>Reviewers</p> <p>This article was reviewed by Eugene Koonin, Rob Knight and Berthold Kastner (nominated by Laura Landweber).</p
Primordial soup or vinaigrette: did the RNA world evolve at acidic pH?
<p>Abstract</p> <p>Background</p> <p>The RNA world concept has wide, though certainly not unanimous, support within the origin-of-life scientific community. One view is that life may have emerged as early as the Hadean Eon 4.3-3.8 billion years ago with an atmosphere of high CO<sub>2 </sub>producing an acidic ocean of the order of pH 3.5-6. Compatible with this scenario is the intriguing proposal that life arose within alkaline (pH 9-11) deep-sea hydrothermal vents like those of the 'Lost City', with the interface with the acidic ocean creating a proton gradient sufficient to drive the first metabolism. However, RNA is most stable at pH 4-5 and is unstable at alkaline pH, raising the possibility that RNA may have first arisen in the acidic ocean itself (possibly near an acidic hydrothermal vent), acidic volcanic lake or comet pond. As the Hadean Eon progressed, the ocean pH is inferred to have gradually risen to near neutral as atmospheric CO<sub>2 </sub>levels decreased.</p> <p>Presentation of the hypothesis</p> <p>We propose that RNA is well suited for a world evolving at acidic pH. This is supported by the enhanced stability at acidic pH of not only the RNA phosphodiester bond but also of the aminoacyl-(t)RNA and peptide bonds. Examples of <it>in vitro</it>-selected ribozymes with activities at acid pH have recently been documented. The subsequent transition to a DNA genome could have been partly driven by the gradual rise in ocean pH, since DNA has greater stability than RNA at alkaline pH, but not at acidic pH.</p> <p>Testing the hypothesis</p> <p>We have proposed mechanisms for two key RNA world activities that are compatible with an acidic milieu: <it>(i) </it>non-enzymatic RNA replication of a hemi-protonated cytosine-rich oligonucleotide, and <it>(ii) </it>specific aminoacylation of tRNA/hairpins through triple helix interactions between the helical aminoacyl stem and a single-stranded aminoacylating ribozyme.</p> <p>Implications of the hypothesis</p> <p>Our hypothesis casts doubt on the hypothesis that RNA evolved in the vicinity of alkaline hydrothermal vents. The ability of RNA to form protonated base pairs and triples at acidic pH suggests that standard base pairing may not have been a dominant requirement of the early RNA world.</p> <p>Reviewers</p> <p>This article was reviewed by Eugene Koonin, Anthony Poole and Charles Carter (nominated by David Ardell).</p
Volunteers and Collections as Viewed from the Museum Mission Statement
This article explores the volunteer program employed at the C. H. Nash Museum at Chucalissa which sees volunteers take a more active role in collections curation
Raman spectroscopy, a non-destructive solution to the study of glass and its alteration
This paper presents the potential of Raman spectroscopy, a non-destructive technique which can be applied in-situ, for the analyses of glass and their alteration. Recent analytical developments are summarised for different glass composition and practical examples are given. The paper describes how to extract compositional information from the glass, first based on the spectra profile to distinguish rapidly alkali silicate from alkaline-earth alkali silicate and lead alkali silicate glass, then using the spectral decomposition and correlations to extract quantitative data. For alkali silicate glasses, that are most prone to alteration, the spectral characteristics are described to interpret the alteration process (selective leaching or dissolution of the glass) from the Raman spectra of the altered glass. These developments have greatly widened the potential of the technique and supplement well its ability to measure the thickness of the altered layer and identify the crystalline deposits
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