1,399 research outputs found
Nicotiana sylvestris, a model plant for cell biology: organelle movement and retrotransposon mutagenesis
No full textNicotiana sylvestris is a diploid tobacco plant that is amenable to laboratory manipulation including facile transformation of nuclear and plastid (chloroplast) genomes. In three separate studies, I used this model organism to observe biological processes with evolutionary and biotechnological implications. The first addresses the mechanisms of horizontal gene transfer by demonstrating cell-to-cell movement of plastids. We grafted Nicotiana sylvestris plants with selectable transgenic plastid genomes to Nicotiana tabacum plants with selectable transgenic nuclear markers. Grafting triggers formation of new cell-tocell contacts, creating an opportunity for organelle movement between the plant cells. I present evidence for cell-to-cell movement of the entire 161-kb plastid genome in these plants, most likely in intact plastids. Acquisition of plastids from neighboring cells provides a mechanism by which cells may be repopulated with functioning organelles. My second objective was to determine whether exceptional pollen transmissionof plastids is accompanied by paternal mitochondria transmission in Nicotiana sylvestris. Plastids and mitochondria in Nicotiana are normally both inherited from the maternal parent. We observed that plastids from the N. sylvestris father were transmitted at a low (~0.002%) frequency via pollen. The plants that inherited paternal plastids did not carry paternal mitochondrial DNA, indicating that leakage of plastids via pollen can produce plant lines with unrelated plastids and mitochondria. My third objective was to observe the behavior of an individual high-copy retrotransposon in N. sylvestris, its native host. Long terminal repeat (LTR) retrotransposons are major components of the nuclear genomes of plants, animals and fungi. The “copy-and-paste” life cycle of retrotransposons accounts for their accumulation in host genomes and permits the assumption that LTRs are identical at the time of insertion. Our objective was to experimentally determine if an introduced synthetic element would interact with native high-copy elements during retrotransposition. I present evidence that S-TNT1 co-packaged with native TNT1 elements to produce hybrid insertions with swapped LTRs and multiple recombinations within the gag-pol gene. We can best explain our observations by dimerization and co-packaging of TNT1 gRNAs in the cytoplasm, followed by template-switching during minus-strand DNA synthesis, which we term the “mixand- paste” pseudodiploid mating system for LTR-retroelements.Ph. D.Includes bibliographical referencesIncludes vitaby Gregory N. Thysse
Antifibrillatory actions of K+ channel blocking drugs
No full textClass III antiarrhythmic drugs share the common mechanism of widening the cardiac action potential without affecting conduction velocity. This thesis reports on the actions of newly developed putative Class III antiarrhythmic drugs, tedisamil, KC 8851, RP 62719, UK 68798, and risotilide, as well as an ATP-sensitive K⁺ channel blocker, glibenclamide. Studies were performed to examine the actions of these drugs in acute myocardial ischaemia and possible mechanisms responsible for these actions. The hypothesis tested was that drug treatment prevented arrhythmias induced by acute myocardial ischaemia. Species dependent actions of these drugs on ECG and blood pressure were examined in rats, guinea pigs, pigs and primates.
The five putative class III drugs listed above were assessed for antiarrhythmic activity in a conscious rat model of myocardial ischaemia. It was found that only tedisamil and KC 8851, which widened the Q-T[formula omitted] interval of the ECG (by up to 65%) , were effective at suppressing fibrillation in this species. None of the drug treatments decreased the incidence of ventricular premature beats. Tedisamil, but not glibenclamide, prevented tachycardias in a rat model of myocardial ischaemia- and reperfusion-induced arrhythmias. In an anaesthetized pig model of acute myocardial ischaemia, tedisamil and UK 68,798 were shown to mildly prolong the Q-T[formula omitted] interval by less than 20%, but protection against arrhythmias was equivocal.
In further studies, tedisamil and UK 68,798 were compared to each other for effects on ventricular epicardial action potential morphology using intracellular recording in vivo, and effects on ventricular effective refractory period using electrical stimulation in vivo in both rats and guinea pigs. Tedisamil (4 mg/kg, i.v.) prolonged rat ventricular epicardial action potential duration fourfold in vivo, while UK68,798 (up to 1 mg/kg, i.v.) was ineffective in this species. Tedisamil (4 mg/kg, i.v.) widened guinea pig ventricular epicardial potentials by 80%, while UK 68,798 (25 μg/kg, i.v.) increased these by 30%. Action potential widening paralleled increases in ventricular refractoriness to electrical induction of premature beats. It was found that the species selective actions of these drugs was most likely related to differences in selectivity for K⁺ channels which contribute to repolarization in myocardium.Medicine, Faculty ofAnesthesiology, Pharmacology and Therapeutics, Department ofGraduat
Using n-grams to identify time periods of cultural influence
No full textAn author's literary style is influenced by the cultural time period in which the author lives. The author's ideas, and the words chosen to express them, can help identify the cultural time period that most influenced the author. Ideas are expressed in language through sequences of words called n-grams. Over the past several years, Google has been engaged in digitizing millions of books. As part of this endeavor, Google has created a database of n-grams extracted from these digitized books, and has made the database available to researchers online. This is the first time ever that such an extensive repository of cultural data has been made available. This study develops and tests an original method for utilizing Google's database to identify the cultural time period that most influenced the author of a published work. Several undisputed literary works are examined, from which sets of n-grams are extracted and compared against the Google database. The frequency and distribution of n-gram matches allow us to determine the cultural time period that most influenced the author. The method is also tested against several literary works having uncertain or disputed authorship and period of composition. The results suggest that the method developed provides a reasonable approximation of the time period of greatest cultural influence for each book. Unexpectedly, the results tend to support conclusions reached by another researcher with regard to prior literary influences on the Ern Malley Poems. In addition, they lend support to a well-known alternate theory on the authorship of the Book of Mormon.M.S
The ‘insider/outsider’ dilemma of ethnography: Working with young children and their families in cross-cultural contexts
No full textIn this article we unravel the difficulty of being researchers in the homes and classrooms of children and
their families whose origins are, for one of us, very different and, for the other, very similar to our own.
We first situate our work within theories of early socialization and literacy teaching which underpin our
understanding of how young children in cross-cultural contexts learn. We then turn to the question of
working with the families and teachers of these children which poses dilemmas not explained by the theories
presented. We illustrate these through a series of vignettes typifying both the ‘Outsider’ and the ‘Insider’ role.
The stories highlight paradigmatic moments of complexity, clashes or collusion which we unpick in terms of
their generalizability for others working in the field. Finally, we extend theories of dialogue in our search for
a methodology for collaborative work in future cross-cultural ethnographic studies
After Faith, Hope, and Love: the Unique Divergence of Asceticism by Gregory the Great and Maximus the Confessor
No full textIn the late sixth and early seventh centuries, asceticism continued as a frequent expression of Christian devotion. Despite communications between the Eastern and Western Churches and a common patristic foundation, theology in the East and West during this time diverged on the results of asceticism. This paper explores this divergence by examining two theologians, Gregory the Great and Maximus the Confessor. Current scholarship has examined Gregory the Great and Maximus the Confessor on their own, yet the dialogue between each tradition and its implications remains understudied. Thus, this study contextualizes Gregory the Great’s On the Song of Songs and Maximus the Confessor’s Letter 2: On Love. Though both agreed on asceticism’s importance, they described its outcome differently. Gregory viewed asceticism’s result as a fuller, but imperfect, knowledge of God, while Maximus saw human deification as its result. While both authors used similar theological traditions, certain theologians, like Pseudo-Dionysus and Augustine, were only used by one author or the other. Because of Maximus’ doctrine of deification, holy men could be revered in the East. Yet, Gregory saw man as imperfect until after death; thus, it was more acceptable to revere relics in the West. Ultimately, grasping this divergence helps explain the Holy Man in the East and West
Prinnciples of Economic -5/E.
No full textPRINCIPLES OF ECONOMICS continues to be the most popular and widely used text in economics classrooms today. The fifth edition features a strong revision of content in all 36 chapters while maintaining the clear, accessible writing style and precise presentation that are the hallmark of this highly respected author. Dozens of new applications emphasize the real-world relevance of economics for today\u27s students through interesting news articles, realistic case studies, and engaging problems. The new edition also features an expanded instructor\u27s resource package designed to assist in course planning and classroom presentation, as well as full integration of content with Aplia. "I have tried to put myself in the position of someone seeing economics for the first time. My goal is to emphasize the material that students should and do find interesting about the study of the economy."--N. Gregory Mankiw
Principles of economics
No full textNow you can master the principles of economics with the help of the most popular, widely-used economics textbook by students worldwide -- Mankiw's PRINCIPLES OF ECONOMICS, 8E. With its clear and engaging writing style, this book emphasizes only the material that will help you better understand the world in which you live, will make you a more astute participant in the economy, and will give you a better understanding of both the potential and limits of economic policy. The latest relevant economic examples bring principles to life. Acclaimed text author N. Gregory Mankiw explains, "I have tried to put myself in the position of someone seeing economics for the first time. My goal is to emphasize the material that students should and do find interesting about the study of the economy." Powerful student-focused digital resources are available in leading MindTap and Aplia digital learning and homework solutions that reinforce the principles presented in this edition
St. Gregory Palamas’s gnoseology in light of the dogma of the incarnation of Christ
No full textThis article is devoted to the problem of correspondence between the gnoseology
of St. Gregory Palamas and the teachings of the Orthodox Church. His gnoseology
contains two theses that caused a significant controversy in the 14th century in the
Byzantine Empire. These are the uncreated nature of the Tabor Light and the possibility
to know God by His uncreated energies, but not by His essence. The author
turns directly to the Christological confessions and other dogmatic texts of the Ecumenical
Councils to solve the problem. This method has not been largely used. As
a general rule, the “palamites” and “antipalamites” used to refer to some particular
father or plunged into a strictly philosophical discourse. At the same time, it was not
fully taken into the account the fact that the Acts of the Ecumenical Councils contain
information to adequately assess St. Gregory’s gnoseology. The article concisely
presents the main theses of St. Gregory Palamas’s gnoseology, approved by the local
Council of 1351 held in Constantinople. The theses are compared to the confession
of the Council of Chalcedon. The texts of the subsequent Ecumenical Councils
are considered to be as clarifying as the Chalcedonian confession. The views of St.
Gregory’s main opponents are also analyzed in the article. Particular attention is
paid to the meaning of key terms in the considered dogmatic texts. The article also
takes into account the philosophical aspect of the problem, and expounds one of the
arguments of St. Gregory in favor of the uncreated nature of the Tabor Light, which
is based on the idea of the inability of human nature to emit light. As a result of the
research, it was established that both theses of St. Gregory contradict the doctrine
of the Ecumenical Councils about Christ. Instead of St. Gregory’s dubious gnoseology,
the Ecumenical Councils offer to cognize the divinity of the Trinity inseparably
from the flesh of Christ, and not only in energy, but also essence and hypostasis. As
for the natural science argument of St. Gregory, it is refuted by the data of modern
science, which proved the existence of biophotons. This discovery, according to the
author, does not contradict, but only confirms the Christology of the Ecumenical
Councils
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
The reception of Qoheleth in a selection of rabbinic, patristic and nonconformist texts
No full textThe purpose of this thesis is to examine the reception of the text of Qoheleth in a selection of rabbinic, patristic and nonconformist literature. The differences in the act of reading, reception and response to this text in discrete
Judaic and Christian locations is examined. The source texts that are considered are Qoheleth Rabbah, Targum Qoheleth, Gregory of Nyssa's homilies and Matthew Henry's exposition on Ecclesiastes. The thesis further investigates historical and theological experiential influences on the reception of Qoheleth as portrayed by the source texts. The text of Qoheleth and its history of interpretation, and the value of
examining the reception of the text by specific readers from a variety of contexts are discussed in the first chapter. In the consecutive chapters the reception of Qoheleth by each source text is examined individually. The historical and
theological contexts of each source text are described, including literary traditions and exegetical principles.
In the detailed examination of the source texts, the textual structural challenges that Qoheleth poses and how and why
they are responded to by the author(s) of the source texts are analysed. The final chapter compares and contrasts the main issues raised by the differing readings of Qoheleth, including the identity of Solomon and the view of God, and also, the differing contextual perspectives in which the reception process took place. Finally, a brief examination of a modem reader's (Michael V Fox') reception of Qoheleth is contrasted with that of earlier readers of the text. The manner in which the potential effects of Qoheleth are actualised and the process of meaning production varies between readers, being conditioned by their historical horizon
- …
