17,713 research outputs found
Complex plasmas: Interaction potentials and non-Hamiltonian dynamics
No full textThis thesis is a cumulative dissertation that consists of three papers.
The first paper addresses the issue of screening of a charged dust particle suspended in the plasma-wall transition layer of a plasma discharge. This problem is one of the fundamental issues in the physics of complex (dusty) plasmas, because the screening of charged dust particles determines the interaction forces between them and thus governs their dynamics. The kinetic model proposed in this paper considers a point charge embedded in a weakly-ionized plasma with ion drift. The latter is considered to be due to an external electric field and assumed to be mobility-limited. Here, "mobility-limited" means that the acceleration of ions in the external field is balanced by collisions of ions with neutrals and that this balance determines the drift velocity. The embedded point charge (i.e., a charged dust particle) perturbs the ion drift, and the resulting potential distribution around the dust particle is calculated. The results are proven to be in agreement with existing measurements performed in the plasma-wall transition layer of a rf plasma discharge. One of the important applications of this work is related to the possibility of tuning the pair interaction potential between dust particles by applying an external oscillating electric field. In particular, such a tuning allows studying electrorheological properties of strongly coupled systems on all relevant time scales. First experiments of this kind have already been performed onboard the International Space Station.
The second paper deals with the dust-lattice waves - oscillations of charged dust particles forming a crystalline structure in a plasma. The role of anisotropic screening of dust particles and variations of their charges is investigated. It is well known that the mentioned effects lead to non-Hamiltonian dynamics of dust particles and, as a result, can trigger an instability of the dust-lattice waves. This instability has been already observed in experiments. The new result is that the mutual influence of particles on their charges, not considered in the analysis of the dust-lattice waves before, is shown to be capable of making a significant contribution to this instability.
The third paper examines whether a similar instability can be observed in a cluster formed by two or three charged dust particles. It is found that an instability due to the non-Hamiltonian dynamics is only possible when the interparticle separation in the cluster is such that certain cluster eigenfrequencies are sufficiently close to each other.Настоящая диссертация является кумулятивной диссертацией и состоит из трех работ.
Первая работа посвящена экранированию заряженной пылевой частицы, левитируемой в приэлектродном слое плазменного разряда. Эта задача является одной из фундаментальных проблем физики пылевой плазмы, так как экранирование заряженных пылевых частиц определяет силы взаимодействия между ними и поэтому определяет их динамику. В статье предложена кинетическая модель, в которой рассматривается точечный заряд, помещенный в слабоионизированную плазму с ионным дрейфом. Предполагается, что ионный дрейф вызван внешним электрическим полем и соответствует мобильности ионов. Последнее означает, что подразумевается баланс между ускорением ионов во внешнем электрическом поле и столкновениями ионов с нейтралами, который и определяет скорость дрейфа. Внесенный точечный заряд (т.е., заряженная пылевая частица) возмущает дрейф ионов, и образующееся распределение потенциала вокруг пылевой частицы вычислено в настоящей работе. Результаты находятся в согласии с ранее опубликованными результатами измерений, выполненными в приэлектродном слое радиочастотного плазменного разряда. Одно из важных приложений этой работы связано с возможностью регулирования потенциала парного взаимодействия пылевых частиц посредством приложения внешнего осциллирующего электрического поля. В частности, такое регулирование позволяет изучать электрореологические свойства систем, в которых потенциальная энергия парного взаимодействия частиц превышает их кинетическую энергию. Первые эксперименты такого типа уже были проведены на борту Международной Космической Станции.
Предметом исследования второй работы являются так называемые пылекристаллические волны - колебания заряженных пылевых частиц, образующих кристаллическую структуру в плазме. Исследована роль как анизотропии экранирования пылевых частиц, так и вариаций их зарядов. Как известно, эти эффекты приводят к негамильтоновой динамике пылевых частиц и поэтому могут вызвать неустойчивость пылекристаллических волн, которая уже была обнаружена в экспериментах. Новый результат заключается в том, что взаимное влияние пылевых частиц на их заряды, которое ранее не учитывалось при анализе пылекристаллических волн, может обеспечить значительный вклад в эту неустойчивость.
В третьей работе исследовано, может ли подобная неустойчивость наблюдаться в кластере, состоящем из двух или трех пылевых частиц. Получено, что подобная неустойчивость из-за негамильтоновой динамики может возникнуть только тогда, когда расстояние между пылевыми частицами близко к резонансному значению, при котором определенные собственные частоты кластера совпадают.Diese Dissertation ist eine kumulative Dissertation und besteht aus drei Arbeiten.
Die erste Arbeit beschäftigt sich mit der Abschirmung des in einer Plasmarandschicht zur Schwebe gebrachten geladenen Staubteilchens. Dieses Problem ist von fundamentaler Bedeutung für die Physik der komplexen (staubigen) Plasmen, weil die Abschirmung die Form der Wechselwirkungen und somit die Dynamik der geladenen Staubteilchen bestimmt. In der Arbeit wird ein kinetisches Modell vorgeschlagen, in welchem ein Staubteilchen als eine Punktladung betrachtet wird, die sich in einem schwach ionisierten Plasma mit einer Ionendrift befindet. Es wird angenommen, dass die Ionendrift durch ein externes elektrisches Feld verursacht wird und dass diese Ionendrift der Mobilität der Ionen entspricht. Dies bedeutet, dass die Beschleunigung der Ionen im externen elektrischen Feld durch Ionen-Neutralteilchen-Stöße ausgeglichen wird und dass diese Kompensation die Geschwindigkeit der Ionendrift bestimmt. Die Punktladung (d.h. das Staubteilchen) stört diese Ionendrift, und in der vorliegenden Arbeit wird die resultierende Potentialverteilung des Staubteilchens im Plasma berechnet. Zudem wird festgestellt, dass die Resultate mit den früher in RF-Entladungen durchgeführten Experimenten konsistent sind. Die übergreifende Bedeutung dieser Untersuchung liegt in der Möglichkeit, damit durch ein externes elektrisches Wechselfeld das binäre Wechselwirkungspotential der Staubteilchen von außen zu steuern und somit z.B. elektrorheologische Eigenschaften von stark wechselwirkenden Systemen von Partikeln sichtbar zu machen und dynamisch auf allen relevanten Zeitskalen zu untersuchen. Erste Messungen dieser Art sind in Experimenten auf der Internationalen Raumstation bereits erfolgreich durchgeführt worden.
Die zweite Arbeit beschäftigt sich mit den sogenannten Staub-Gitter-Wellen (dust-lattice waves). Das sind Wellen, die durch Schwankungen der geladenen Staubteilchen, die eine Kristallstruktur im Plasma bilden, entstehen. In der vorliegenden Arbeit wird die Rolle sowohl der Anisotropie der Abschirmung der Staubteilchen als auch der Variation ihrer Ladungen untersucht. Wie bekannt führen diese Effekte zu nicht-Hamiltonischer Dynamik der Staubteilchen und können daher eine Instabilität der Staub-Gitter-Wellen auslösen. Solche Effekte sind in Experimenten bereits beobachtet worden. Das neue Ergebnis besteht darin, dass der gegenseitige Einfluss der Staubteilchen auf ihre Ladungen, ein Effekt, welcher bisher bei der Analyse der Staub-Gitter-Wellen noch nicht berücksichtigt wurde, einen wichtigen Beitrag zu dieser Instabilität leisten kann.
In der dritten Arbeit wird untersucht, ob eine ähnliche Instabilität in Partikelclustern, welche nur aus zwei oder drei Staubteilchen bestehen, beobachtet werden kann. Es wurde festgestellt, dass eine ähnliche Instabilität, die durch nicht-Hamiltonische Dynamik verursacht ist, nur dann möglich ist, wenn der Teilchenabstand so gewählt wird, dass bestimmte Eigenfrequenzen des Clusters gut miteinander übereinstimmen
After Sulla: study in the settlement and material culture of the Piraeus peninsula in the Roman and Late Roman period
No full textModem text-based and ancient historical accounts take the sack of Piraeus, the port of Athens in Greece, by the Romans under Sulla in 86 ВС as the terminal point of the history of the area in antiquity. Archaeological work on the town has tended so far to regard the post-Classical phases of the settlement as less interesting than those marking the 'heyday' of the port in the Classical period. This thesis explores the nature and scale of settlement in the area in the centuries spanning the town's destruction by the Romans in 86 ВС and the Late Roman period. The study is based on a re-assessment of archaeological data from old and recent rescue excavations in the modem town up to 1997. It also presents and discusses in detail the results of post-excavation work by the author on unpublished material from an extensive site excavated in the early 1980s, These results are compared to and synthesized with epigraphic and other testimonies to answer questions about the nature of settlement and the degree of social and cultural change in the area during the period in focus. The discussion focuses in particular on; 1) exploring continuity and change in the settlement patterns, demography and topography of the town, 2) the changing nature of domestic space and its organization, and 3) investigating patterns of pottery consumption and trade. These issues are examined in the context of the social, economic and cultural changes documented for the Roman imperial and Late Roman period by previous archaeological fieldwork and excavations in the region of southern Greece and the Aegean
A re-examination of the evidence for parade-grounds at auxiliary forts in Roman Britain
No full textThis Thesis examines the underlying evidence for parade-grounds at auxiliary forts in Roman Britain. Firstly by examining the evidence supporting forts with actual physical remains, such as the altars and the tribunal at Maryport and the artificially levelled area at Hardknott, and those with flagged areas which have been interpreted as parade-grounds, such as Ambleside and Gelligaer. The literary evidence of ancient authors is examined with particular reference to training and exercising and where this might have been undertaken. The occasions when a parade might have been appropriate in Roman times are examined, as is the possibility of a modem concept being superimposed on an ancient action
Re-Thinking Ritual Traditions: Interpreting Structured Deposition in Watery Contexts in Late Pre-Roman Iron Age and Roman Britain
No full textThis investigation seeks to define the strands of continuity and change in structured deposition across the Late Pre-Roman Iron Age to Early Roman transition in Britain, and interpret their significance in terms of cultural interaction. These interpretations not only examine and re-think structured deposition in relation to ritual traditions, but also explore how the continuity of such traditions was impacted by the transition between these two periods. Metalwork is a central focus but a wide range of other finds are also considered in order to take a holistic perspective on deposition. Watery deposits were an obvious starting point but comparisons with dry context deposits were necessary to provide a more complete understanding of these practices. The data were gathered from a number of individual sites throughout two contrasting case study zones defined by major waterways and labelled as such: the Severn-Thames Axis in the south and the Solway-Forth Axis in the north of Britain. Through the use of site reports as the main source of data, the analysis took a two-tiered approach. Individual episodes of structured deposition were examined and interpreted on a site-by-site basis. This then led to investigations on a broader scale by examining changes in the continuity of practices in the type of finds deposited, the contexts into which deposition took place and pre-deposition practices, such as deliberate breakage to determine patterns of deposition across the case study zones as a whole. With this comparative analysis it can be concluded that watery contexts were not a unique locus of structured deposition, and indeed that this practice is highly diverse across the zones studied. The tempora
The Empire, the Land, and the Exodus: A Study of How the Roman Empire Literally Shaped Christianity: 1 C.E. - 280 C.E.
No full textThis paper explores the factors and trends involved in the movement of Christian communities from Palestine into Asia Minor and regions west of the Aegean Sea. Because the first generation of Christians generally continued to identify themselves as Jewish, this paper looks into the factors that affected the Jewish community with the perspective that a large portion of the early Christians were still members of the Jewish community. Roman land control policies, taxation, and continuous loss and division of land all but pushed many Jews out of the region while the peace of Augustus led many more to depart more voluntarily. It was the culmination of all these factors that led to Jewish emigration from the Palestinian region. The paper will begin with a brief history of the birth of Christianity and the Jewish-Roman relationship in Palestine, followed by a discussion of factors that led to emigration from Palestine, and then end with an analysis of the locations of the Christian communities
Beyond the Foreigner: representations of non-roman individuals and communities in latin historiography, from Sallust to Ammianus Marcellinus
No full textFrom the foundation of the city of Rome in 753 BCE to the capture of the same in 476 CE, the ancient Romans came into contact with a diverse range of peoples. The Romans did not want only to conquer these peoples and incorporate them into the empire, but also they displayed a genuine interest in learning about foreigners. Roman historical narrative demonstrates clearly this prevailing curiosity. This thesis examines the representations of foreign individuals and communities in five works: SaUust, helium lugurthinum; Livy, Ab Vrhe Condita 21-30; Justin, Epitome of Pompeius Trogus, Historiae Philippicae 11-12; Tacitus, Germania; Ammianus MarcelHnus, Res Gestae 23.6. These authors represent a broad range of types of history writing (monograph, AUG history, universal history), and they span most of die history of Rome as an empire (40s BCE to the late 300s CE). Moreover, these works represent a diverse range of geographic locations in that they include the three major parts of the world as understood by the Romans: Africa, Europe and Asia. Finally, they cover—or they exist within the context of—the full range of the Roman-Foreign experience: victory (Numidia, Carthage), defeat (Persia), and non- result (Germani).This thesis demonstrates that Roman historians employ a diverse range of presentations of non-Roman individuals and communities. Roman historians appear not to have been constrained by a narrow set of rules when it comes to writing non- Romans; rather, each author can be seen to be engaging in a wider Roman discourse on the foreigner. And this discourse extends beyond the Roman world and Roman historical writing: the historians of Rome can be seen as building upon, and responding to, the so-called father of history, Herodotus, whose own narrative established firmly that exploration of the foreigner is an important part of historical inquiry. Close analysis clearly demonstrates each presentation of a non-Roman character or community to be an intricate and fascinating construction, and understanding how the foreigner is conceptualised in the work is of critical importance. On the one hand, the presentation of foreigners fits into the historian’s overarching aims and objectives in his work; on the other hand, the representation of foreigners can dictate the ways in which the Roman history is narrated. Non-Romans both fit into and they provide direction for, Roman historical narrative. By studying the complexities of the presentation of non-Romans, therefore, this thesis enhances our understanding of the sophistication of Roman historical writing. Despite the continuing acknowledgement of the important role ethnography plays in writings of Herodotus and his Greek and Roman successors and imitators, there has not so far been a genre-wide detailed study of the ethnography in Greek or Roman historiography. This thesis, therefore, seeks to rectify partially this omission on the part of scholarship, and establish a foundation for future study of the non-Roman in Latin literature and Roman culture
Epitome of Roman history [electronic resource] /
No full textFlorus (second century CE) wrote, in brief pointed rhetorical style, a two-book summary of Roman history (especially military) in order to show the greatness and decline of Roman morals. Based chiefly on Livy and perhaps planned to reach Florus' own times, the extant work ends with Augustus's reign (30 BCE-14 CE).First published (with Cornelius Nepos) 1929; this separate edition 1984.Includes bibliography and index.Florus (second century CE) wrote, in brief pointed rhetorical style, a two-book summary of Roman history (especially military) in order to show the greatness and decline of Roman morals. Based chiefly on Livy and perhaps planned to reach Florus' own times, the extant work ends with Augustus's reign (30 BCE-14 CE).Mode of access: World Wide Web.Description based on print version record
Traditions and Transitions: Later and Roman Iron Age Communities in the North-East of England
No full textThis thesis aims to reintegrate the communities of later Iron Age north-east of England (from roughly 300 BC) into wider narratives of later Iron Age and Roman-era Europe. Despite the significant contributions of George Jobey, Colin Haselgrove and others, the north-eastern Iron Age has been widely considered underpopulated and materially and culturally impoverished since such a view was put forward by Mortimer Wheeler and Stuart Piggott in the 1950’s. In light of this impression of the later Iron Age, the region has been seen as a ‘blank slate’ for the establishment of a Roman military zone which has then been interpreted without fully considering an indigenous, civilian population.
Recent work on later Iron Age settlements and non-military Roman era settlements in the region has called these older views more directly into question by building on the work of Jobey and Haselgrove and demonstrating that a substantial Roman and pre-Roman civilian population must have been present across the region throughout the period in question. Thus, this study has sought to bring together the available artefactual, depositional and architectural evidence for later Iron Age communities as well as those Roman-era communities who maintained connections with indigenous traditions. Though there can be no clear separation of ‘indigenous’ and ‘Roman’ settlements from the mid first century onwards, this study has focused on those settlements which continue to make use of roundhouse architecture.
Given the variable state of the evidence from the long tradition of investigation in the region, only well contextualized excavated evidence is considered in order to best shed light on the practice of daily life. Alongside considering the range of material culture in use, contextual analysis of this evidence demonstrates that the noted lack of recovered material culture, particularly ceramics, can be shown to be the result of deliberate choices in acquisition, use and deposition of material culture which reflect the priorities of this decentralized society rather than the result of an inability to produce or trade. Despite this however, it is clear that northeastern communities do appear to engage in similar depositional activities to other British and European Iron Age societies, albeit on a smaller scale which reflects the smaller scale of the communities involved, and a deep connectedness to wider traditions can be shown. Considered alongside this sometimes difficult dataset is the history of Iron Age studies in the region and how this has shaped research strategies. This is an illustrative example of the mechanisms through which older, broad brush understandings can continue to dominate regional archaeologies despite newer, more nuanced evidence.
As well as a case study in the relevance of the history of archaeology to contemporary study, the narrative thus constructed provides a basis for understanding the north-eastern Iron Age within the expanding web of regionalization and connections which was Iron Age Europe. Additionally it provides a narrative of indigenous communities’ interactions with and reactions to the dramatic changes related to the expansion of the Roman empire the early first millennium AD. This is ultimately key in order to better interpret the increasing evidence for non-military Roman era communities in the region and beyond
Adam Smith and Roman Servitudes
No full textThis essay is a preprint of an article that appeared at: Tijdschrift voor Rechstsgeschiedenis, 72 (2004), 327–57.This essay discusses Adam Smith historical jurisprudence and his use of Roman law materials in his Lectures on Jurisprudence. It argues that Smith found it difficult to maintain his theory of legal development in the face of a highly developed body of Roman law literature
Review of Regulating Sex in the Roman Empire: Ideology, the Bible, and the Early Christians
No full textIn Regulating Sex in the Roman Empire, David Wheeler-Reed takes on the ambitious project of mapping the various ideologies of marriage and sexuality in the Roman Empire, Judaism, the New Testament, and early Christianity, in an effort to understand the relationship these ideologies have to contemporary "Judeo-Christian" family values. His main argument is that "Christian groups that want to (re)establish so-called Judeo-Christian values in this country�have codified the imperial discourse of Augustus, with its emphasis on marriage and procreation, instead of early Christian ideology�which emphasized singleness" (xx). Relying on Foucauldian ideas about the relationship between discourse and power (e.g., xiv-xv), coupled with Deleuzian "map-making" (104), Wheeler-Reed eschews totalizing history (105) in favor of "a study of ideologies" (xi). He writes in an easy, readable, perhaps even conversational style unsual for monographs so heavily steeped in critical theory. Most impressive, however, is Wheeler-Reed�s command of an immense amount of ancient material spanning from Achilles Tatius to the Dead Sea Scrolls, Paul to John Cassian, and Philo to Jovinian
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