1,298 research outputs found

    Location of the free thiol group in bovine [beta]-lactoglobulin A, B, and C : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry at Massey University

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    Under non-reducing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) conditions unheated samples of β-lactoglobulin (β-LG) A, B and C all run as a single band, the A variant having a slightly lower mobility than the B and C variants. Following heating of these samples to 110°C, two bands are seen in the monomer region of SDS-PAGE gels run under non-reducing conditions. As heat can induce disulphide exchange, the individual bands forming the doublet may represent species of the same molecular size but having different arrangements of the disulphide bonds. The band formed in the A variant as a result of heating appears to have the same mobility as the unheated B and C variants, while the band formed in the B and C variants as a result of heating appears to have the same mobility as the unheated A variant. Under reducing conditions only a single band was seen in both heated and unheated samples, and the mobility of this band is the same in all three variants. This indicates that the difference in mobility between variants seen in non-reduced samples involves disulphide bonding. If the difference in the mobility of the two bands seen in heated samples is due to a difference in the position of a disulphide bond, and thus the free thiol, then it is possible that the position of the free thiol group in the A variant is different to that of the B and C variants even in unheated samples of this protein. A difference in the distribution of the thiol could explain observed differences in the reactivity of this group. The purpose of this study was to determine whether the observed differences in the mobility of unheated samples of purified bovine β-LG A, B and C under non-reducing SDS-PAGE conditions is due to a difference in the location of the free thiol group within the primary sequence of these variants. This was achieved by reacting the β-LG variants with a radioactively labelled thiol-reactive reagent [1,4-14C] N-ethylmaleimide (14C-NEM), thereby attaching a radioactive marker to the free thiol group. Following labelling of the protein, carried out under conditions that did not induce band splitting, the protein was hydrolysed and the resulting labelled peptide was purified and sequenced. The free thiol group was found to be at residue 121 in β-LG A, B and C. Therefore differences in mobility during non-reduced SDS PAGE of β-LG A, B and C are not due to a difference in the location of the thiol group. However, results indicate that it is possible that, particularly in the B and C variants, there is a tendency for disulphide exchange to occur, even under relatively mild conditions. In establishing the conditions under which band splitting did not occur, the effect of exposure to various conditions on the mobility of purified β-LG variants on native-PAGE and SDS-PAGE was studied. The mobilities of caprine β-LG and porcine β-LG were also studied in order to further characterise the factors within the primary sequence of β-LG that have an influence on band splitting. With bovine β-LG A, B and C, band splitting was found to be both temperature- and pH- dependent. Protein concentration and the ionic strength of the buffer also appeared to effect band splitting. Heating also induced the formation of aggregated species, visible on both native and SDS-PAGE gels. The presence of aggregated material on SDS-PAGE gels indicates that disulphide bonding is involved in the formation of these species. On native-PAGE, material that ran as a smear between the monomer band and dimer band was observed following heating. The protein present in this region may represent monomeric β-LG that has been sufficiently denatured for its mobility under native-PAGE to be retarded. Comparisons of the amount of material present in monomeric forms under native and non-reduced SDS-PAGE suggest that multiple monomeric species of β-LG are present in heated samples. Storage at -18°C in SDS-PAGE sample buffer was also shown to induce changes in the mobility of bovine β-LG A, B and C, and of caprine β-LG, on SDS-PAGE. Storage under these conditions caused the aggregation of β-LG but did not induce band splitting. The banding pattern in the dimer region of the stored samples differed between the variants, with the A variant showing a banding pattern that was markedly different to that of the B and C variants and the caprine protein, which showed similar patterns. The bovine β-LG B and C and caprine β-LG showed similar tendencies to form aggregates, and had a greater tendency to form these high molecular weight species than β-LG A. These differences may be due to a difference in the reactivity of the free thiol group under these conditions, influenced by the substitution at position 118. Purified, unheated caprine β-LG ran as a single band in non-reduced SDS gels, and appeared to have the same mobility as the unheated bovine B and C variants under these conditions. Heating of caprine β-LG also induced the formation of a second band with a similar mobility to that of unheated β-LG A. Caprine β-LG has an Asp at position 64 (as found in bovine β-LG A) and an Ala at position 118 (as found in bovine β-LG B and C). The fact that in non reducing SDS-PAGE caprine β-LG runs as a band with a similar mobility to bovine β-LG B and C and a slightly higher mobility than bovine β-LG A suggests that the substitution at position 118 in the primary protein sequence may somehow be causing the mobility difference. Aggregated material was also seen in caprine β-LG following heating. Unheated samples of porcine β-LG ran as two bands under non-reduced SDS-PAGE. Heating the porcine β-LG did not appear to induce any change in the appearance of the two bands, and there was no evidence of aggregation of this protein. Bovine β-LG A, B and C and caprine β-LG all contain a free cysteine residue in their protein sequence. Porcine β-LG does not contain a free Cysteine and thus the lack of heat-induced changes to the banding pattern in porcine β-LG when compared with the bovine variants and caprine β-LG is possibly due to the absence of this potentially reactive thiol group. The presence of a free thiol group appears to be required both to induce band splitting and for the formation of higher molecular weight aggregates following heating. Band splitting is thus probably a consequence of disulphide interchange reactions, the interchange reaction in β-LG A causing a second band to run in the position of β-LG Band C, and the interchange reaction in β-LG B and C causing a second band to run in the position of β-LG A

    Fairy Letters

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    Poetry by Brittan Semler

    Stanford University’s John Otterbein Snyder: Student, Collaborator, and Colleague of David Starr Jordan and Charles Henry Gilbert

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    John Otterbein Snyder (1867–1943) was an early student of David Starr Jordan at Stanford University and subsequently rose to become an assistant professor there. During his 34 years with the university he taught a wide variety of courses in various branches of zoology and advised numerous students. He eventually mentored 8 M.A. and 4 Ph.D. students to completion at Stanford. He also assisted in the collection of tens of thousands of fish specimens from the western Pacific, central Pacific, and the West Coast of North America, part of the time while stationed as “Naturalist” aboard the U.S. Fish Commission’s Steamer Albatross (1902–06). Although his early publications dealt mainly with fish groups and descriptions (often as a junior author with Jordan), after 1910 he became more autonomous and eventually rose to become one of the Pacific salmon, Oncorhynchus spp., experts on the West Coast. Throughout his career, he was especially esteemed by colleagues as “a stimulating teacher,” “an excellent biologist,” and “a fine man

    The outcome of the WTO ministerial in Singapore. European Union News No. 74/96, 13 December 1996

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    European Commission Vice President Sir Leon Brittan today made the following statement: "This Conference has been a huge international success, giving a vital boost to the strength and profile of the World Trade Organization (WTO). The Singapore Government and the WTO Secretariat deserve credit for making such a success possible

    Watching Androids Dream of Electric Sheep: Immersive Technology, Biometric Psychography, and the Law

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    Virtual reality and augmented reality present exceedingly complex privacy issues because of the enhanced user experience and reality-based models. Unlike the issues presented by traditional gaming and social media, immersive technology poses inherent risks, which our legal understanding of biometrics and online harassment is simply not prepared to address. This Article offers five important contributions to this emerging space. It begins by introducing a new area of legal and policy inquiry raised by immersive technology called “biometric psychography.” Second, it explains how immersive technology works to a legal audience and defines concepts that are essential to understanding the risks that the technology poses. Third, it analyzes the gaps in privacy law to address biometric psychography and other emerging challenges raised by immersive technology that most regulators and consumers incorrectly assume will be governed by existing law. Fourth, this Article sources firsthand interviews from early innovators and leading thinkers to highlight harassment and user experience risks posed by immersive technology. Finally, this Article compiles insights from each of these discussions to propose a framework that integrates privacy and human rights into the development of future immersive tech applications. It applies that framework to three specific scenarios and demonstrates how it can help navigate challenges, both old and new

    "CHILE AND EUROPE: WORKING TOGETHER ON THE NEW TRADE CHALLENGES". Remarks by The Right Honourable Sir Leon Brittan QC Vice-President of the European Commission. Santiago, 2 April 1997

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    It is fitting that the central speaking engagement of my official visit to Chile should take place before a distinguished gathering of businessmen such as this. In the global economy, on which Europe as well as Chile depends so heavily for future prosperity, it is business as much as public administration that calls the shots. Businessmen of partner nations must talk more, not only with each other but with their governments, in order to ensure that we on the political side understand what business needs for the decades ahead. In the case of Chile and Europe, the needs seem to me very much on the same lines

    Coca-Cola Curses: Hate Speech in a Post-Colonial Context

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    Hate speech is a contextual phenomenon. What offends or inflames in one context may differ from what incites violence in a different time, place, and cultural landscape. Theories of hate speech, especially Susan Benesch’s concept of “dangerous speech” (hateful speech that incites violence), have focused on the factors that cut across these paradigms. However, the existing scholarship is narrowly focused on situations of mass violence or societal unrest in America or Europe. This paper discusses how online hate speech may operate differently in a postcolonial context. While hate speech impacts all societies, the global South—Africa in particular—has been sorely understudied. I posit that in postcolonial circumstances, the interaction of multiple cultural contexts and social meanings form concurrent layers of interpretation that are often inaccessible to outsiders. This study expands the concept of online harms by examining the political, social, and cultural dimensions of data-intensive technologies. The paper’s theories are informed by fieldwork that local partners and I conducted in Kasese, Uganda in 2019–2020, focusing on social unrest and lethal violence in the region following the 2016 elections. The research, completed with assistance from the Berkeley Human Rights Clinic, included examining the background and circumstances of the conflict; investigating social media’s role in the conflict; designing a curriculum around hate speech and disinformation for Ugandan audiences; creating a community-sourced lexicon of hateful terms; and incorporating community-based feedback on proposed strategies for mitigating hate speech and disinformation. I begin this with a literature review of legal theory around hate speech, with a particular focus on Africa, and then turn to the legal context around hate speech and social media use in Uganda, examining how the social media landscape fueled past conflicts. Then I explain my Kasese fieldwork and the study’s methodology, before describing initial results. I follow with a discussion of applications to industry, specifically how hate speech is defined and treated by Meta’s Facebook, the dominant social media provider in Kasese. It progresses to a discussion of the implications of the study results and legal and policy recommendations for technology companies stemming from these findings. Importantly, I apply the research findings to expand existing scholarship by proposing a new sixth “hallmark of dangerous speech” to augment Benesch’s paradigm. Adding “calls for geographic exclusion” as a new qualifier for dangerous speech stems from the particular characteristics embodied by postcolonial hate speech. Examples from the Kasese study illustrate how this phenomenon upends platforms’ expectations of hate speech—which may not consider “Coca-Cola bottle” to be an epithet. The application of this new hallmark will create a more inclusive understanding of hate speech in localized contexts. This paper’s conclusions and questions may challenge platforms that must address hate speech and content moderation at a global scope and scale. It will examine the prevalence and role of social media platforms in Africa, and how these platforms have provided resources and engagement with civil society in these regions

    Co-designing in the real world: managing a multiple stakeholder design process with an NGO

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    Many ICT4D research projects work in collaboration with NGOs in order to meet their development objectives and to increase their interventions’ effectiveness. Herein, aspects of co-design are often applied, where the intention is to include all stakeholders as equal participants in the design process. However, collaborating with NGOs and with users who have reduced access to technology can be challenging. As a result, the ideals of co-design are not easily achieved, due to the vastly differing backgrounds of stakeholders in ICT4D projects. In this thesis, an explicit approach for managing the varying interactions between stakeholders is proposed and described through a case study. The approach was derived from ethnographic action research and participatory design methodologies, led by practical consideration from real-world constraints. The approach is structured around an interactive design process that includes the stakeholder groups in unique ways at each phase of the design process, in order to maximise the contributions in a way that respects their backgrounds and areas of expertise. The proposed approach was evaluated through its implementation in the design of a mobile recordkeeping application, in collaboration with an NGO in Cape Town, South Africa. The NGO comprises of two stakeholder groups: the staff and the micro-entrepreneurs who they empower. The NGO’s focus is to provide training and support over a two-year process to women from low-income communities, by teaching them how to manage their own businesses to become socially and financially independent. The objective of this case study was to design a mobile application that aligned with the recordkeeping curriculum of the NGO and meet the specific requirements and constraints of the target users. Through the implementation of the design approach, the students and staff were able to provide useful and complementary contributions towards the design of the system. A one-month field study of the application with a group of 21 student participants revealed that the system was a suitable solution and appropriately met the needs of the NGO and the end-users. The final evaluation of the stakeholders’ reflections on the design process revealed that it was an appropriate design process to have followed. The results further identified that care must be taken to clarify expectations at each stage of the design process, especially when external factors change, and to frequently communicate with all stakeholders involved. The design approach proposed and employed during this research project, and the unique way that it allowed the stakeholders to contribute, will benefit future ICT4D research projects that are faced with stakeholder groups that vary significantly, where traditional equal participation is not possible

    A comparative study of predictors of academic achievement for agricultural college students, employing academic, demographic, and psychological variables.

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    This study was designed to examine variables which may predict academic success at a College of Agricultural Technology. One hundred and seventy-three first-year students--99 males and 74 females--were tested to determine their pre-college accreditation in English, Math, Biology and/or Chemistry, their farm or non-farm backgrounds, locus of control, motivation for learning, Canadian Adult Achievement test scores, personality characteristics, and first-semester college grades. Regression analyses were computed to determine those variables predictive of academic success. Scores on standardized tests of literacy and numeracy skills were predictive. No significant relationship was evident with the other variables, leading to the conclusion that pre-admission accreditation, demographic characteristics, and the psychological measures tested did not predict academic achievement. Thus, the hypothesis that proficiency in the fundamental disciplines of literacy and numeracy generalize to enhance performance in college was justified. It was suggested that incumbent on colleges and universities is responsibility for bridging the gap in literacy skills experienced by those applicants who have completed secondary school, but have not acquired adequate facility in communication to enable them to achieve success in their personal and professional lives. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1997 .B745. Source: Masters Abstracts International, Volume: 37-01, page: 0024. Adviser: L. L. Morton. Thesis (M.Ed.)--University of Windsor (Canada), 1997
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