2,688 research outputs found
Supplementary material for Existence of the Wealth-Consumption Ratio in Asset Pricing Models with Recursive Preferences
No full textOnline appendix as well as code to numerically compute the existence condition in equation (18) for discrete time affine models as in equation D.1 of the online appendix
Ole Miss Faculty and Staff Retirees Invited to Presentation
Get PDFLocal historian and author Jack Mayfield to speak at Inn at Ole Mis
Ole Miss Faculty and Staff Retirees Invited to Presentation
Get PDFLocal historian and author Jack Mayfield to speak at Inn at Ole Mis
Coping in Nordic Peripheries - on the Spatial Production of Societies
Get PDFIn many traditional approaches the notion of “society” has been taken for given as a territorial container of modern society per se, and regional development was only a question of how to organise and distribute within societies. However, increasingly globalisation, flows and networks across borders have been seen as the new dominant forces of the 21st century, and traditional approaches to regional development are seen as trapped in territorial understandings. The paper seeks to develop a third position that highlights the constitutive forces of spatial practices to the development of modernity in Nordic peripheries. Hence, the spatial practices inherent in coping strategies, regional policies, planning and other aspects of regional development are interpreted not as effects or consequences of social orders, but as producers of social orders. Specific focus is given to the constitutive role of the territorial orders of municipalities and the protestant church in the formation of, often surprising, modern orders in Nordic peripheries in the 20th century. The paper draws on and develops empirical and theoretical insights from the UNESCO MOST Circumpolar Coping Processes Project (co-ordinated by the author, see www.unesco.org/most/p91.htm and www.uit.no/MostCCPP).
Best-selling Author Lawrence Otis Graham to Sign New Book Oct. 24 at Ole Miss Bookstore
No full textOXFORD, Miss. -- New York Times best-selling author Lawrence Otis Graham is scheduled to sign and read from his latest book Tuesday (Oct. 24) at the University of Mississippi. Graham is to be at the Ole Miss Bookstore in the Student Union at 12:30 p.m. to promote The Senator and the Socialite: The True Story of America\u27s First Black Dynasty (HarperCollins, 2006)
Jack Ford: Why I Love Ole Miss
No full textCBS News Legal Analyst and author Jack Ford loves visiting Ole Miss and the Grove, especially on game weekends. Video by Mary Stanton Knighthttps://egrove.olemiss.edu/umvideo/1467/thumbnail.jp
Jüri Okas’ ‘specific objects’: diverging discourses in Estonian Art in the 1970s.
No full textPreviously in the University eprints HAIRST pilot service at http://eprints.st-andrews.ac.uk/archive/00000367/Article 3 of 6 in issue devoted to the visual culture of the Scandinavian and Baltic region.This article will look at the early works of Estonian architect and artist Jüri Okas and will try to work between diverging languages and interpretations, reading works by Okas against the background of Anglo-american conceptualism and minimalism of the same period. The first part of the paper will analyse a print by Jüri Okas that paraphrases works by the American artist Donald Judd and will try to show how Okas’ concept of minimalism differed from the Western one and the reasons behind it. The second part of the paper will focus on a conceptual book by Jüri Okas, consisting of a series of photographs of everyday and banal architectural objects, and compare it to Rober Venturi’s book on Complexity and Contradiction in Architecture. Finally, a comparison will be made with works of Robert Smithson in the context of concepts of waste, excess and the remainders of industrial civilisationPostprin
Asset pricing with climate risks and heterogeneous beliefs
No full textThis thesis analyzes how climate risks are priced on financial markets. We show that climate tipping thresholds, disagreement about climate risks, and preferences that price in long-run risks are crucial to an understanding of the impact of climate change on asset prices. Our model simultaneously explains several findings that have been established in the empirical literature on climate finance: (i) news about climate change can be hedged in financial markets, (ii) the share of green investors has significantly increased over the past decade, (iii) investors require a positive, although small, climate risk premium for holding “brown” assets, and (iv) “green” stocks outperformed “brown” stocks in the period 2011–2021. The model can also explain why investments in mitigating climate change have been small in the past. Finally, the model predicts a strong, non-linear increase in the marginal gain from carbon-reducing investments as well as in the carbon premium if global temperatures continue to rise.This thesis also presents an adapted numerical solution approach based on projection methods and Gauss-Hermite quadrature to solve long-run risk asset-pricing models with disasters and heterogeneous agents, where closed-form solutions are unavailable. We demonstrate an effective approach for handling nonlinearities, such as a tipping threshold. The proposed approach demonstrates sufficient accuracy in solving the equilibrium conditions, making it computationally efficient even for models involving multiple states and agents
Vote for Ole Hanson postcard, 1918
No full textOle Hanson (1874-1940) was a man who packed multiple lives into one. He's best known in Washington for his role, as Seattle's mayor, in ending the city's General Strike of 1919, but he's also well known for founding the city of San Clemente, California, six years later. Though opportunistic and erratic, Hanson was a shrewd politician and realtor who left fascinating stories in his wake.
This postcard features a portrait of Mr. Hanson and an encouragement by an unnamed author to support Mr. Hanson's campaign in the mayoral election of 1918.Caption information by: "Hanson, Ole Thorsteinsson (1874-1940)" by Phil Dougherty, HistoryLink.org Essay 11101.1 postcard: b&w; 5.5 x 3.5 in
X-ray Observations of Accreting Compact Objects
No full textKapitel 5: König, O. et al, Long term variability of Cygnus X-1. VIII. A spectral-timing look at low energies with NICER, Astronomy & Astrophysics, submittedIn meiner Dissertation untersuche ich die Physik akkretierender kompakter Objekte in Doppelsternsystemen. Die Akkretion von Materie eines Begleitsterns führt zu der Bildung einer turbulenten Scheibe um das kompakte Objekt, die effizient gravitative potenzielle Energie in Strahlung umwandelt. In Schwarzlochdoppelsternen kann stark variable Röntgenstrahlung mit weltraumbasierten Teleskopen detektiert werden. Sie entsteht durch Comptonisierung in direkter Nähe des Schwarzen Lochs. Die genaue Geometrie dieser Region ist jedoch umstritten. Bereits kurz nach der Entdeckung des ersten Schwarzen Lochs, Cygnus X-1, wurde erkannt, dass die Variabilität im harten Röntgenwellenlängenbereich genutzt werden kann um Aussagen über die Struktur der innersten Region des Systems zu treffen. Wie sich jedoch die Variabilität der Akkretionsscheibe auf das generelle Verhalten der Quelle auswirkt, kann nur zuverlässig in der weichen Röntgenstrahlung betrachtet werden. Diese Studien sind in den letzten Jahren durch eine neue Röntgenmission möglich geworden.
Cygnus X-1 zeigt Übergänge zwischen einem spektral harten Zustand, der von comptonisierter Emission dominiert ist, und einem weichen Zustand, in dem die Strahlung der Akkretionscheibe dominiert. In meiner Arbeit untersuche ich zum ersten Mal die Variabilität von Cygnus X-1 bei Energien <1keV in diesen Zuständen anhand der Neutron Star Interior Composition Explorer (NICER) Beobachtungskampagne. Ich untersuche die Verbindung der Variabilität zwischen niedrigen und hohen Energien, welche sehr kohärent im harten Spektralzustand ist. Die hohe Kohärenz zeigt, dass es einen Prozess gibt, der die Variabilität verbindet, was stark vermuten lässt, dass es einen kausalen physikalischen Zusammenhang zwischen den Fluktuationen der Akkretionsscheibe und der Variabilität in der comptonisierenden Region gibt. Ich zeige, dass sich dieser Prozess im weichen Spektralzustand fundamental ändert, da die Variabilität inkohärent wird.
Im harten Spektralzustand können zwei etablierte Variabilitätskomponenten identifiziert werden. Ich zeige, dass diese Komponenten vermutlich individuellen physikalischen Prozessen in der Akkretionsscheibe und der comptonisierenden Region zugeordnet werden können. Ich entdecke ein neues Variabilitätsphänomen, das klar zwischen diesen beiden Variabilitätskomponenten lokalisiert und nur bei niedrigen Energien zu sehen ist. Es kann charakterisiert werden durch eine abrupte Änderung in den Ankunftszeiten der harten (>2keV) und weichen (<1,5keV) Photonen, zusammen mit einer Reduktion der Kohärenz. Das Phänomen ist fundamental mit den Variabilitätskomponenten verbunden und folgt ihrer wohlbekannten Verschiebung zu höheren Frequenzen wenn Cygnus X-1 weicher wird. Ich zeige, dass das Phänomen nicht nur eine Eigenschaft von Cygnus X-1 ist, sondern auch im harten Spektralzustand von transienten Röntgendoppelsternen zu sehen ist, was die Entdeckung einer neuen generellen Eigenschaft akkretierender Schwarzer Löcher in Doppelsternsystemen suggeriert.
Im zweiten Teil meiner Dissertation betrachte ich einen Nova Ausbruch eines akkretierenden Weißen Zwerges. In Doppelsternsystemen mit einem Spenderstern sammelt sich wasserstoffreiche Materie in einer Hülle auf der Oberfläche des Weißen Zwerges. Sobald die Hülle eine kritische Masse erreicht hat, startet eine instabile thermonukleare Explosion, wodurch die Hülle abrupt expandiert und ihre meiste Masse verliert. Dieser Ausbruch wird Nova genannt. Seit über 30 Jahren sagt die Novatheorie die Existenz einer "Feuerball" Phase voraus, die direkt der Kettenreaktion folgt. Diese Phase sollte als weicher, heller und kurzer Röntgenblitz zu sehen sein, bevor die Nova im optischen Licht sichtbar wird. Der Blitz ist jedoch schwierig zu detektieren, da Novae normalerweise durch ihren Helligkeitsanstieg im sichtbaren Licht entdeckt werden. Zu diesem Zeitpunkt ist der Röntgenblitz schon vorbei.
Ich präsentiere die klare Detektion eines extrem hellen und sehr weichen Röntgenblitzes von der klassischen galaktischen Nova YZ Reticuli, beobachtet mit dem extended ROentgen Survey with an Imaging Telescope Array (eROSITA) Weltraumteleskop. Der Blitz fand 11 Stunden vor dem 9 Magnituden starken Anstieg im optischen Licht statt und hatte eine maximale Helligkeit von 3,7 Magnituden. Auf der Südhalbkugel war die Quelle für etwa fünf Tage mit dem bloßen Auge sichtbar. Vier Stunden vor und nach dem Ereignis wurde keine Röntgenquelle detektiert, wodurch die Dauer des Blitzes auf unter acht Stunden begrenzt werden konnte. Diese Detektion kann eindeutig der Feuerballphase von YZ Reticuli zugeordnet werden.
Die Hauptherausforderung der Analyse ist die extreme Helligkeit der Quelle, die zu schwerwiegender Übersättigung im Detektor führte. Ein detailliertes Verständnis der physikalischen Prozesse im Halbleitermaterial ist notwendig, um die resultierenden Verzerrungen des Spektrums zu verstehen. Der Simulator SIXTE ist in der Lage, diese komplexen Detektoreffekte zu modellieren. Mithilfe eines simulationsbasierten Minimierungsprozesses kann ich so die physikalischen Parameter der Quelle rekonstruieren, insbesondere die Temperatur, Leuchtkraft und Absorption der Photosphäre.
In Übereinstimmung mit theoretischen Vorhersagen kann das Spektrum der Quelle mit einem Schwarzkörper einer Temperatur von 3,27+0,11-0,33 x 105 K (28,2+0,9-2,8 eV), oder eines Atmosphärenmodells, modelliert werden. Die Photosphäre emittiert mit der Eddington-Leuchtkraft und ist nur etwas größer als ein Weißer Zwerg. Diese Detektion einer expandierenden Photosphäre eines Weißen Zwergs vor der Abstoßung der Hülle bildet das letzte Verbindungsstück des vorhergesagten photosphärischen Lichtkurvenverlaufs und eröffnet neue Möglichkeiten, um die gesamte Energetik der Nova zu vermessen.In my dissertation, I study the physics of accreting compact objects in binary systems. Accretion of matter from a stellar companion leads to the formation of a turbulent disk around the compact object, which efficiently converts gravitational potential energy into radiation. In black hole binaries, strongly variable X-rays can be detected with space-based telescopes. This radiation originates from Comptonization in a region of disputed geometry in the direct vicinity of the black hole. Already shortly after the discovery of the first black hole, Cygnus X-1, it was realized that the hard X-ray variability can be used to probe the innermost region of the system. How the variability of the accretion disk impacts the general behavior of the source, however, can only be reliably studied in the soft X-ray regime. In recent years, these studies have become possible with a new X-ray mission.
Cygnus X-1 shows transitions between a spectrally hard state, where the emission is dominated by Comptonization, and a soft state, where the accretion disk dominates the radiation. For the first time, I study the variability properties of Cygnus X-1 at soft X-rays <1keV in these spectral states using the monitoring campaign of the Neutron Star Interior Composition Explorer (NICER). I study the connection of the variability at low and high energies, which is highly coherent in the hard state. The high coherence shows that there is a process at work which links the variability, providing evidence for a causal physical connection between the fluctuations from the accretion disk and the variability of the Comptonized emission. I show that this process fundamentally changes in the soft state, where the variability becomes incoherent.
In the hard state, two well-known variability components can be identified. I show that these components likely represent individual physical processes associated with the disk and Comptonized emission. I discover a new variability phenomenon that is prominently seen in between the two variability components, and only emerges at low energies. It can be characterized by an abrupt change of the arrival times of hard (>2keV) and soft (<1.5keV) photons, together with a coherence drop. This feature is fundamentally connected to the variability components, and follows their well-known shift to higher frequencies as Cygnus X-1 softens. I show that the feature is not only a property of Cygnus X-1 but is also clearly detected in the hard state of transient low-mass X-ray binaries, suggesting a new general property of accreting black hole binaries.
In the second part of my thesis, I study a nova outburst of an accreting white dwarf system. In a binary system with a donor star, hydrogen-rich material accumulates in an envelope on the surface of the white dwarf. Once the envelope has reached critical mass, the system undergoes runaway thermonuclear burning, which results in the envelope to expand rapidly and to eject most of its mass. This outburst is called a nova. For more than 30 years, nova theory has predicted the existence of a "fireball" phase following directly on from the runaway fusion, which should be observable as a short, bright, and soft X-ray flash before the nova becomes visible in the optical. This flash is difficult to observe because novae are usually discovered when the source rises in the visual light. At this time, the X-ray flash has, however, already ceased.
I present the unequivocal detection of an extremely bright and very soft X-ray flash of the classical Galactic nova YZ Reticuli observed with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) space telescope. The flash occurred 11 hours before its 9 mag optical brightening. The source had a peak brightness of 3.7 mag, and was visible to the naked eye in the southern hemisphere for about five days. No X-ray source was detected 4 hours before and after the event, constraining the duration of the flash to shorter than 8 hours. The detection can be clearly associated with the fireball phase in YZ Reticuli.
The main challenge of this analysis is the extreme brightness of the source, which led to severe pile-up in the detector. A detailed understanding of the physical processes in the semiconductor detector is necessary to understand the resulting spectral distortions. The simulator SIXTE is capable of modeling these complex detector effects. Using a simulation-based fitting approach, I could reconstruct the physical parameters of the source, in particular, the temperature, luminosity, and absorption of the photosphere.
In agreement with theoretical predictions, the source's spectral shape is consistent with a black body of 3.27+0.11-0.33 x 105 K (28.2+0.9-2.8 eV) radiating at the Eddington luminosity, with a photosphere that is only slightly larger than a typical white dwarf. This detection of the expanding white dwarf photosphere before the ejection of the envelope provides the last link of the predicted photospheric lightcurve evolution and opens a new window to measure the total nova energetics
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