1,123 research outputs found
Seitz and Stackelberg on Oligopoly.
No full textThis essay deals with the contribution of Seitz and Stackelberg on oligopoly. Stackelberg's theory on price leadership has been taken up by Seitz in his dissertation of 1965. The author summarizes the debate in Germany in the beginning of the sixties on oligopoly theory between Krelle, Ott, Heertje, Helmstadter und Seitz. He looks back from a game theoretical point of view.oligopoly, Nash-equilibrium, Stackelberg, Seitz, Krelle, game theory, Cournot, two-period game, one-shot game
Le métal mal-aimé de la construction en France depuis un siècle : des raisons de coût ?
No full textFrédéric Seitz. The century-long neglect of metal in French construction : a question of cost ?
The high price of metal is often invoked reasons to explain its minimal use in French architecture and building. The author uses informations taken from Price Series to evaluate this argument for the period 1875 to World War 2. He argues that the underuse of metal cannot be explained by economic considerations. Instead he focuses on the actors involved in metallic construction : producers, masterbuilders and contractors.Frédéric Seitz. Le métal mal-aimé de la construction en France depuis un siècle : des raisons de coût ?
Le coût du métal et de sa mise en œuvre est l'une des raisons souvent invoquée pour expliquer la faible part qui est réservée à ce matériau dans l'architecture et la construction françaises. L'auteur
examine ici cette question pour la période qui s'étend de 1875 à la veille de la seconde guerre mondiale, à partir des informations contenues dans les Séries de Prix. Concluant que le sous-emploi du métal dans le cadre bâti ne peut s'expliquer par des considérations économiques, il suggère que cette problématique soit abordée par référence non pas seulement au matériau lui-même, mais aussi au rôle des acteurs de la construction métallique : fabriquants de matériaux, maîtres d'ouvrage, maîtres d'œuvre et entrepreneurs.Seitz Frédéric. Le métal mal-aimé de la construction en France depuis un siècle : des raisons de coût ?. In: Histoire & Mesure, 1994 volume 9 - n°1-2. Varia. pp. 147-169
A Vulnerability Management Solution for constrained IoT devices with a Trusted Execution Environment using a Hardware Root of Trust
No full textThe popularity and prevalence of Internet of Things (IoT) devices has been ever increasing. They have found their way into our everyday lives and increasingly transform our living environments into smart homes. However, most of these constrained devices do not possess sufficient computational power, memory, and battery runtime in order to implement security features that are common for general purpose personal computers. Hence, the increasing numbers of interconnected consumer IoT devices are followed by an increase of their attack surface and vulnerabilities.
The following thesis approaches this security issue by providing a novel approach for a Runtime IoT Security Score that provides the inexperienced user of a smart home system with profound insight into the security state of the connected IoT devices during runtime. This is achieved by combining Vulnerability Assessment with Trustworthiness Assessment of the connected devices, which has never been proposed before and represents a very valuable contribution to the state of current research.
In addition to the Runtime Security Score, a holistic concept for a Vulnerability Assessment and Management (VAM) solution is proposed as another main contribution of this thesis. The effective and functional interoperability of all relevant components specified in this concept is shown with a Proof of Concept implementation.Die Popularität und Verbreitung von Geräten des Internets der Dinge (engl.~Internet of Things, IoT) nimmt ständig zu. Sie haben Einzug in unser tägliches Leben gehalten und verwandeln unsere Wohnumgebung zunehmend in ein intelligentes Zuhause. Die meisten dieser eingeschränkten Geräte verfügen jedoch nicht über genügend Rechenleistung, Speicher und Akkulaufzeit, um Sicherheitsfunktionen zu implementieren, die für allgemeine Personal Computer üblich sind. Mit der zunehmenden Zahl der vernetzten IoT-Geräte für Verbraucher steigen daher auch deren Angriffsfläche und Schwachstellen.
Die vorliegende Arbeit widmet sich diesem Sicherheitsproblem, indem sie einen neuartigen Ansatz für einen Runtime IoT Security Score vorstellt, der dem unerfahrenen Benutzer eines Smart-Home-Systems einen tiefen Einblick in den Sicherheitszustand der angeschlossenen IoT-Geräte zur Laufzeit gibt. Dies wird durch die Kombination von Vulnerability Assessment mit einer Bewertung der Vertrauenswürdigkeit der angeschlossenen Geräte erreicht. Dies stellt einen neuartigen Ansatz darf und leistet damit einen sehr wertvollen Beitrag zum aktuellen Stand der Forschung.
Neben dem Runtime Security Score wird als weiterer wichtiger Beitrag dieser Arbeit ein ganzheitliches Konzept für eine Vulnerability Assessment and Management (VAM) Lösung vorgeschlagen. Die effektive und funktionale Interoperabilität aller relevanten Komponenten, die in diesem Konzept spezifiziert sind, wird mit einer Proof of Concept Implementierung gezeigt
Intra-individual cortical networks in Anorexia Nervosa: Evidence from a longitudinal dataset
No full textObjective: This work investigates cortical thickness (CT) and gyrification patterns in Anorexia Nervosa (AN) before and after short-term weight restoration using graph theory tools. Methods: 38 female adolescents with AN underwent structural magnetic resonance imaging scans at baseline and after - on average - 3.5 months following short-term weight restoration while 53 age-matched healthy controls (HCs) were scanned once. Graph measures were compared between groups and longitudinally within the AN group. Associations with clinical measures such as age of onset, duration of illness, BMI standard deviation score (BMI-SDS), and longitudinal weight changes were tested via stepwise regression. Results: Cortical thickness graphs of patients with acute AN displayed lower modularity and small-world index (SWI) than HCs. Modularity recovered after weight gain. Reduced global efficiency and SWI were observed in patients at baseline compared to HCs based on gyrification networks. Significant associations between local clustering of CT at admission and BMI-SDS, and clustering/global efficiency of gyrification and duration of illness emerged. Conclusions: Our results indicate a shift towards less organised CT networks in patients with acute AN. After weight recovery, the disarrangement seems to be partially reduced. However, longer-term follow-ups are needed to determine whether cortical organizational patterns fully return to normal
The great island : some observations in and about Newfoundland
No full textSeitz's interest in Newfoundland developed after having been befriended by a Newfoundland dog as a young boy. In December of 1926, the author set out on a journey to visit the ancestral home of his old friend, this book being the outcome of his travels. Seitz paints a very vivid picture of Newfoundland for his readers, skillfully describing Newfoundland and Labrador, the people, and their way of life while also relaying the facts about the colony's mineral resources, fishing industries, religion, and politics. The author also includes details which would be of particular interest to tourists, such as a brief history of the colony, hunting and fishing opportunities and regulations, the Newfoundland dog, and modes of transportation available to get to Newfoundland and for use when one has arrived
'The Wyandots: Being the History of an American Indian Nation Whose Warriors Never Surrendered'
No full textComplete history of the Wyandot Indians written by Don C. Seitz of Fairfield County, Ohio. This typed draft with corrections includes a glossary of Wyandot language (p. 265-270) compiled by N. O. Walker and Mary McKee, and a muster roll of all Wyandot Indians who emigrated west of the Mississippi River in July 1843 (p. 359-361). Chapters include "The Nation," "The Sandusky Country," "The Turmoil,"Dunmore, Logan, Cornstalk," "The Moravians," "The Massacre of the Christians," "Battle Island," "Tymochte," "Escape of Knight and Slover," "Unsettled Relationships," "The Defeats of Harmar and St. Clair," "Efforts at Peace," "Wayne's Victory," "Boone, Kenton, Poe," "Tecumseh and the Prophet," "Eighteen Hundred and Twelve," "The Missions," "The Pressure," "The Migration," "Life in the West," "Kansas-Nebraska," "The Canadian Remnant," "The White Indians," "Government and Society," "Traditions," and "Characteristics.
Prädiktive Middleware-basierte Mobilitätsunterstützung für multikriterielle Handover
No full textDiese Dissertation befasst sich mit Mobilitätsunterstützungen für moderne mobile Endgeräte, welche auf das Internet zugreifen sollen. Zuerst werden die zahlreichen existieren Lösungen klassifiziert, wofür Anforderungen definiert wurden, welche sich an "unbedarften Nutzern" orientieren. Es wird gezeigt, dass lediglich die Gruppe der Middleware-basierten Mobilitätsunterstützungen diese Anforderungen erfüllen kann. Da aber bislang keine Umsetzung verfügbar war, wurde die "Roaming-Enabled Architecture" (REACH) entwickelt. REACH setzt Proxyserver ein, welche als "Ankerpunkte" fungieren und die Server im Internet vor den negativen Auswirkungen von Mobilitätsereignissen abschotten. Es werden eine Vielzahl an Fragestellungen diskutiert, unter anderem "Dreiecks-Routing", die Nutzung nicht modifizierter Anwendungen, längerfristige Isolationssituationen sowie eine auf Prädiktion basierende Handoverentscheidung. Zudem beherrscht REACH "weichere vertikale Handover" sowie Kanalbündelungsszenarien.This doctoral thesis deals with mobility extensions for modern mobile devices that want to access resources of the Internet. At first, the existing approaches are classified, with requirements that were derived with focus on normal users. These users want to use their mobile devices in scenarios that involve mobility. It is shown that only the group of middleware-based solutions is able to fulfil these requirements. However, none of the existing solutions was suitable, thus the "Roaming-Enabled Architecture" (REACH) was created.
REACH implements such a middleware-based approach and was designed to fulfil all requirements. It involves proxy servers that act as "anchor points" isolating the servers in the Internet from the negative effects of mobility. By connecting to multiple proxy servers at the same time, REACH is able to minimize the negative effects of "triangle routing". Furthermore, it was challenging to intercept the data streams of the unmodified applications, to apply the protection schemes of REACH. Multiple possibilities are discussed, and it is a special feature of REACH that they are all available and can be combined with each other. Long lasting isolation situations are not problematic, and REACH is the first mobility extension that is able to involve the users.
Additionally, a predictive handover management scheme is presented. It is able to analyze signal strength measurements of wireless networks to predict link loss events before they actually happen. REACH is able to involve any network access technology, as long as it offers access to the Internet. "Softer handovers" are possible as well as channel bundling scenarios. The testbed already supports Ethernet, WIFI and is able to involve GPRS by accessing a cellphone that is connected via bluetooth. REACH offers a practical solution to allow Internet access in mobile environments. Tests were made in order to underline this. Therefore, REACH was already presented during multiple public demonstrations, where a diversified audience was present.Die vorliegende Dissertation befasst sich mit Mobilitätsunterstützungen für moderne mobile Endgeräte, welche auf das Internet zugreifen sollen. Um die Vielzahl der bereits verfügbaren Lösungen zu klassifizieren, werden Anforderungen definiert, welche sich an "unbedarften Nutzern" orientieren, die ihre Geräte wie gewohnt auch im mobilen Umfeld benutzen möchten. Es stellte sich heraus, dass lediglich die Gruppe der Middlewarebasierten
Mobilitätsunterstützungen diese Anforderungen erfüllen kann. Da jedoch noch keine der gefundenen Lösungen dazu in der Lage war, wurde die "Roaming-Enabled Architecture" (REACH) entwickelt.
REACH tritt mit der Maßgabe an, alle gestellten Anforderungen zu erfüllen. Dazu werden Proxyserver eingesetzt, welche als "Ankerpunkte" fungieren und die Server im Internet vor den negativen Auswirkungen von Mobilitätsereignissen abschotten. Werden mehrere Proxyserver gleichzeitig involviert, kann sogar den negativen Auswirkungen durch das "Dreiecks-Routing" entgegengewirkt werden. Eine große Herausforderung bestand jedoch darin, die Datenströme der nicht modifizierten Anwendungen abzufangen, damit die Sicherungsmechanismen von REACH greifen können. Dazu wird eine Vielzahl an Möglichkeiten diskutiert, wobei ein besonderes Leistungsmerkmal von REACH darin besteht, diese Mechanismen auch in Kombination anbieten zu können. So stellen beispielsweise längerfristige Isolationssituationen keine Probleme mehr für die Anwendungen dar, und es steht erstmalig eine Mobilitätsunterstützung zur Verfügung, welche in solchen Situationen auch die Benutzer mit einbeziehen kann.
Weiterhin wird ein prädiktiv arbeitender Handoverentscheider vorgestellt, welcher durch Beobachtung von Signalstärkewerten drahtlos arbeitender Netzzugangstechnologien drohende Abrisse erkennen kann. REACH unterstützt prinzipiell beliebige Netzzugangstechnologien, solange diese einen Zugang zum Internet ermöglichen können, und erlaubt "weichere vertikale Handover" sowie Kanalbündelungsszenarien. So kommen im Demonstrator bereits drahtgebundenes Ethernet, drahtloses arbeitendes WLAN sowie GPRS mittels eines per Bluetooth angebundenen Mobiltelefons zum Einsatz. Der Demonstrator stellt eine praxistaugliche Mobilitätsunterstützung dar, was durch Tests belegt wird und bereits während zahlreicher praktischer Vorführungen einem breit gefächerten Publikum vorgestellt werden konnte
Search for hadronic resonance in multijet final states with the CDF detector
No full textThis thesis describes a search for a new hadronic resonance in 3.2 fb{sup -1} of data using the Collider Detector at Fermilab. The Fermilab Tevatron accelerator collides beams of protons and antiprotons at a center of mass energy of {radical}s = 1.96 TeV. A unique approach is presented to extract multijet resonances from the large QCD background. Although the search is model independent, a pair produced supersymmetric gluino decaying through R-parity violation into three partons each is used to test our sensitivity to new physics. We measure these partons as jets, and require a minimum of six jets in an event. We make use of the kinematic features and correlations and use an ensemble of jet combinations to distinguish signal from multijet QCD backgrounds. Our background estimates also include all-hadronic t{bar t} decays that have a signature similar to signal. We observe no significant excess in an invariant mass range of 77 GeV/c{sup 2} to 240 GeV/c{sup 2} and place 95% C.L. limits on {sigma}(p{bar p} {yields} {tilde g}{tilde g} {yields} 3jets + 3jets) as a function of gluino invariant mass
Mobility management in IP-Based Networks
No full textMobile communication networks experience a tremendous development clearly
evident from the wide variety of new applications way beyond classical
phone services. The tremendous success of the Internet along with the
demand for always-on connectivity has triggered the development of All-IP
mobile communication networks. Deploying these networks requires, however,
overcoming many challenges. One of the main challenges is how to manage the
mobility between cells connecting through an IP core in a way that
satisfies real-time requirements. This challenge is the focus of this
dissertation. This dissertation delivers an in-depth analysis of the
mobility management issue in IP-based mobile communication networks. The
advantages and disadvantages of various concepts for mobility management in
different layers of the TCP/IP protocol stack are investigated. In
addition, a classification and brief description of well-known mobility
approaches for each layer are provided. The analysis concludes that network
layer mobility management solutions seem to be best suited to satisfy the
requirements of future All-IP networks. The dissertation, therefore,
provides a comprehensive review of network layer mobility management
protocols along with a discussion of their pros and cons. Analyses of
previous work in this area show that the proposed techniques attempt to
improve the performance by making constraints either on access networks
(e.g. requiring a hierarchical topology, introducing of intermediate nodes,
etc.) or mobile terminals (e.g. undertaking many measurements, location
tracking, etc.). Therefore, a new technique is required that completes
handoffs quickly without affecting the end-to-end performance of ongoing
applications. In addition, it should place restrictions neither on access
networks nor on mobiles. To meet these requirements, a new solution named
Mobile IP Fast Authentication protocol (MIFA) is proposed. MIFA provides
seamless mobility and advances the state of the art. It utilizes the fact
that mobiles movements are limited to a small set of neighboring subnets.
Thus, contacting these neighbors and providing them in advance with
sufficient data related to the mobiles enable them to fast re-authenticate
the mobiles after the handoff. The dissertation specifies the proposal for
both IPv4 and IPv6. The specification of MIFA considers including many
error recovery mechanisms to cover the most likely failures. Security
considerations are studied carefully as well. MIFA does not make any
restrictions on the network topology. It makes use of layer 2 information
to optimize the performance and works well even if such information is not
available.In order to analyze our new proposal in comparison to a wide
range of well-known mobility management protocols, this dissertation
proposes a generic mathematical model that supports the evaluation of
figures such as average handoff latency, average number of dropped packets,
location update cost and packet delivery cost. The generic model considers
dropped control messages and takes different network topologies and
mobility scenarios into account. This dissertation also validates the
generic mathematical model by comparing its results to simulation results
as well as results of real testbeds under the same assumptions. The
validation proves that the generic model delivers an accurate evaluation of
the performance in low-loaded networks. The accuracy of the model remains
acceptable even under high loads. The validation also shows that simulation
results lie in a range of 23 %, while results of real testbeds lie in a
range of 30 % of the generic model?s results. To simplify the analysis
using the generic mathematical model, 4 new tools are developed in the
scope of this work. They automate the parameterization of mobility
protocols, network topologies and mobility scenarios. This dissertation
also evaluates the new proposal in comparison to well-known approaches
(e.g. Mobile IP, Handoff-Aware Wireless Access Internet Infrastructure
(HAWAII), etc.) by means of the generic mathematical model as well as
simulation studies modeled in the Network Simulator 2. The evaluation shows
that MIFA is a very fast protocol. It outperforms all studied protocols
with respect to the handoff latency and number of dropped packets per
handoff. MIFA is suitable for low as well as high speeds. Moreover, there
is no significant impact of the network topology on its performance. A main
advantage of MIFA is its robustness against the dropping of control
messages. It remains able to achieve seamless handoffs even if a dropping
occurs. The performance improvement is achieved, however, at the cost of
introducing new control messages mainly to distribute data concerning
mobile terminals to neighbor subnets. This results in more location update
cost than that resulting from the other mobility management protocols
studied. Due to excluding any constraints on the network topology, MIFA
generates the same packet delivery cost as Mobile IP and less than other
protocols.An additional focus of this dissertation is the development of an
adaptive eLearning environment that personalizes eLearning contents
conveying the topics of this dissertation depending on users?
characteristics. The goal is to allow researchers to quickly become
involved in research on mobility management, while learners such as
students are able to gain information on the topics without excess detail.
Analyses of existing eLearning environments show a lack of adaptivity
support. Existing environments focus mainly on adapting either the
navigation or the presentation of contents depending on one or more
selected users? characteristics. There is no environment that supports both
simultaneously. In addition, many user characteristics are disregarded
during the adaptivity process. Thus, there is a need to develop a new
adaptive eLearning environment able to eliminate these drawbacks. This
dissertation, therefore, designs a new Metadata-driven Adaptive eLearning
Environment (MAeLE). MAeLE generates personalized eLearning courses along
with building an adequate navigation at run-time. Adaptivity depends mainly
on providing contents with their describing metadata, which are stored in a
separate database, thus enabling reusing of eLearning contents. The
relation between the metadata that describe contents and those describing
learners are defined accurately, which enables a dynamic building of
personalized courses at run-time. A prototype for MAeLE is provided in this
dissertation as well
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