Spectral states and accretion geometries in Galactic black hole binaries

Black hole X-ray binaries, binary systems where matter from a companion star is accreted by a stellar mass black hole, thereby releasing enormous amounts of gravitational energy converted into radiation, are seen as strong X-ray sources in the sky. As a black hole can only be detected via its interaction with its surroundings, these binary systems provide important evidence for the existence of black holes. There are now at least twenty cases where the measured mass of the X-ray emitting compact object in a binary exceeds the upper limit for a neutron star, thus inferring the presence of a black hole. These binary systems serve as excellent laboratories not only to study the physics of accretion but also to test predictions of general relativity in strongly curved space time. An understanding of the accretion flow onto these, the most compact objects in our Universe, is therefore of great importance to physics. We are only now slowly beginning to understand the spectra and variability observed in these X-ray sources. During the last decade, a framework has developed that provides an interpretation of the spectral evolution as a function of changes in the physics and geometry of the accretion flow driven by a variable accretion rate. This doctoral thesis presents studies of two black hole binary systems, Cygnus~X-1 and GRS~1915+105, plus the possible black hole candidate Cygnus~X-3, and the results from an attempt to interpret their observed properties within this emerging framework. The main result presented in this thesis is an interpretation of the spectral variability in the enigmatic source Cygnus~X-3, including the nature and accretion geometry of its so-called hard spectral state. The results suggest that the compact object in this source, which has not been uniquely identified as a black hole on the basis of standard mass measurements, is most probably a massive, ~30 Msun, black hole, and thus the most massive black hole observed in a binary in our Galaxy so far. In addition, results concerning a possible observation of limit-cycle variability in the microquasar GRS~1915+105 are presented as well as evidence of `mini-hysteresis' in the extreme hard state of Cygnus X-1.

Shock acceleration in the solar corona

In this thesis acceleration of energetic particles at collisionless shock waves in space plasmas is studied using numerical simulations, with an emphasis on physical conditions applicable to the solar corona. The thesis consists of four research articles and an introductory part that summarises the main findings reached in the articles and discusses them with respect to theory of diffusive shock acceleration and observations. This thesis gives a brief review of observational properties of solar energetic particles and discusses a few open questions that are currently under active research. For example, in a few large gradual solar energetic particle events the heavy ion abundance ratios and average charge states show characteristics at high energies that are typically associated with flare-accelerated particles, i.e. impulsive events. The role of flare-accelerated particles in these and other gradual events has been discussed a lot in the scientific community, and it has been questioned if and how the observed features can be explained in terms of diffusive shock acceleration at shock waves driven by coronal mass ejections. The most extreme solar energetic particle events are the so-called ground level enhancements where particle receive so high energies that they can penetrate all the way through Earth's atmosphere and increase radiation levels at the surface. It is not known what conditions are required for acceleration into GeV/nuc energies, and the presence of both very fast coronal mass ejections and X-class solar flares makes it difficult to determine what is the role of these two accelerators in ground level enhancements. The theory of diffusive shock acceleration is reviewed and its predictions discussed with respect to the observed particle characteristics. We discuss how shock waves can be modeled and describe in detail the numerical model developed by the author. The main part of this thesis consists of the four scientific articles that are based on results of the numerical shock acceleration model developed by the author. The novel feature of this model is that it can handle complex magnetic geometries which are found, for example, near active regions in the solar corona. We show that, according to our simulations, diffusive shock acceleration can explain the observed variations in abundance ratios and average charge states, provided that suitable seed particles and magnetic geometry are available for the acceleration process in the solar corona. We also derive an injection threshold for diffusive shock acceleration that agrees with our simulation results very well, and which is valid under weakly turbulent conditions. Finally, we show that diffusive shock acceleration can produce GeV/nuc energies under suitable coronal conditions, which include the presence of energetic seed particles, a favourable magnetic geometry, and an enhanced level of ambient turbulence.

Towards a United States of Africa? Combining Zambian and AU level debate.

Globalisaatio on luonut uuden maailmanjärjestelmän jonka myötä yksittäisten valtioiden vaikutusvalta on vähentynyt entisestään. Tämä pitää paikkansa erityisesti kehittyvien maiden kohdalla, esimerkiksi Afrikassa. Afrikka on pyrkinyt taistelemaan globalisaation tuomia negatiivisia vaikutuksia vastaan alueellistumisen ja maanosan yhtenäisyyttä ajavien hankkeiden kautta jo vuosikymmenien ajan, mutta toistaiseksi tulokset eivät ole olleet vakuttavia. Tällä hetkellä Afrikan Unionissa keskustellaan hankkeesta muodostaa Afrikan Yhdysvallat. Aiemmista hankkeista poiketen tämän uuden aloitteen ajatus perustuu ylikansallisuudelle, jossa yksittäiset valtiot luovuttavat valtaansa ylikansallisille elimille, kuten Afrikan Unionin hallitukselle. Näin ollen on tärkeää tarkastella aloitetta Afrikan Yhdysvaltojen perustamiseksi ja arvioida, voisiko tällainen ylikansallinen organisaatio auttaa Afrikkaa kääntämään globalisaation haittavaikutukset myönteisiksi. Tämä Pro Gradu-tutkielma väittää sen olevan mahdollista, mutta vain siinä tapauksessa että Afrikka on valmis hyväksymään yhtenäisyyden rajoitukset. Aiemman tutkimuksen vähyyden vuoksi on myös tarpeen tutkia Afrikan Yhdysvalloista kansallisilla tasoilla käytävää keskustelua. Tämän vuoksi tässä tutkielmassa painotetaan esimerkkimaa Sambian kautta yhden Afrikan Unionin jäsenmaan keskinäistä keskustelua aiheesta ja verrataan sitä Afrikan Unionin tason keskusteluun. Tutkielma sisältää kirjallisuuskatsauksen sekä tapaustutkimuksen. Tutkimusaineisto koostuu sambialaisista sanomalehtiotteista sekä Sambian valtion ja Afrikan Unionin virallisista asiakirjoista. Pääasiallisena tutkimusmenetelmänä on laadullinen sisällönanalyysi. Teoreettinen viitekehys perustuu afrikkalaisen valtion ja kansalaisyhteiskunnan, alueellistumisen, globalisaation hallinnan, pan-afrikkalaisuuden ja poliittisen integraation teorioihin sekä historialliseen katsaukseen Afrikan yhtenäisyydestä. Perimmäisenä tarkoituksena on lisätä ymmärrystä afrikkalaisesta valtiosta ja politiikasta. Tutkimuksen tulosten mukaan on havaittavissa aukko valtioiden virallisten toimijoiden näkemysten ja kansalaisyhteiskunnan huolenaiheiden välillä. Viralliset toimijat näyttävät olevan kansalaisyhteiskuntaa vahvemmin Afrikan Yhdysvaltojen kannalla. Virallisten toimijoiden korostaessa Afrikan aatteellista yhtenäisyyttä kansalaisyhteiskunta on huolissaan sen toteutumisesta käytännössä. Esiin nousee myös kysymys 'afrikkalaisesta' identiteetistä ja kansalaisuudesta sekä kommunikaatiosta valtion ja kansalaisten välillä.

Measurement of the b-hadron production cross section using decays to μ-D0X final states in pp̅ collisions at √s=1.96 TeV

We report a measurement of the production cross section for b hadrons in pp̅ collisions at √s=1.96  TeV. Using a data sample derived from an integrated luminosity of 83  pb-1 collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze b hadrons, Hb, partially reconstructed in the semileptonic decay mode Hb→μ-D0X. Our measurement of the inclusive production cross section for b hadrons with transverse momentum pT>9  GeV/c and rapidity |y|<0.6 is σ=1.30  μb±0.05  μb(stat)±0.14  μb(syst)±0.07  μb(B), where the uncertainties are statistical, systematic, and from branching fractions, respectively. The differential cross sections dσ/dpT are found to be in good agreement with recent measurements of the Hb cross section and well described by fixed-order next-to-leading logarithm predictions.

Measurement of the b-hadron production cross section using decays to μ-D0X final states in pp̅ collisions at √s=1.96 TeV

We report a measurement of the production cross section for b hadrons in pp̅ collisions at √s=1.96  TeV. Using a data sample derived from an integrated luminosity of 83  pb-1 collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze b hadrons, Hb, partially reconstructed in the semileptonic decay mode Hb→μ-D0X. Our measurement of the inclusive production cross section for b hadrons with transverse momentum pT>9  GeV/c and rapidity |y|<0.6 is σ=1.30  μb±0.05  μb(stat)±0.14  μb(syst)±0.07  μb(B), where the uncertainties are statistical, systematic, and from branching fractions, respectively. The differential cross sections dσ/dpT are found to be in good agreement with recent measurements of the Hb cross section and well described by fixed-order next-to-leading logarithm predictions.

Measurement of the b-hadron production cross section using decays to μ-D0X final states in pp̅ collisions at √s=1.96 TeV

We report a measurement of the production cross section for b hadrons in p-pbar collisions at sqrt{s}=1.96 TeV. Using a data sample derived from an integrated luminosity of 83 pb^-1 collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze b hadrons, H_b, partially reconstructed in the semileptonic decay mode H_b -> mu^- D^0 X. Our measurement of the inclusive production cross section for b hadrons with transverse momentum p_T > 9 GeV/c and rapidity |y|

Studies on Stone Age Housepits in Fennoscandia (4000 - 2000 cal BC) : Changes in ground plan, site location and degree of sedentism

Housepits have a remarkably short research history as compared to Fennoscandian archaeological research on the Stone Age in general. The current understanding of the numbers and the distribution of Stone Age housepits in the Nordic countries has, for the most part, been shaped by archaeological studies carried out over the last twenty to thirty years. The main subjects of this research are Neolithic housepits, which are archaeological remains of semi-subterranean pithouses. This dissertation consists of five peer-reviewed articles and a synthesis paper. The articles deal with the development of housepits as seen in the data gathered from Finland (the Lake Saimaa area and south-eastern Finland) and Russia (the Karelian Isthmus). This synthesis expands the discussion of the changes observed in the Papers to include Fennoscandian housepit research as a whole. Certain changes in the size, shape, environmental location, and clustering of housepits extended into various cultures and ecological zones in northern Fennoscandia. Previously, the evolution of housepits has been interpreted to have been caused by the adaptation of Neolithic societies to prevailing environmental circumstances or to re-organization following contacts with the agrarian Corded Ware/Battle Axe Cultures spreading to North. This dissertation argues for two waves of change in the pithouse building tradition. Both waves brought with them certain changes in the pithouses themselves and in the practices of locating the dwellings in the environment/landscape. The changes in housepits do not go hand in hand with other changes in material culture, nor are the changes restricted to certain ecological environments. Based on current information, it appears that the changes relate primarily to the spread of new concepts of housing and possibly to new technology, as opposed to representing merely a local response to environmental factors. This development commenced already before the birth of the Corded Ware/Battle Axe Cultures. Therefore, the changes are argued to have resulted from the spreading of new ideas through the same networks that actively distributed commodities, exotic goods, and raw materials over vast areas between the southern Baltic Sea, the north-west Russian forest zone, and Fennoscandia.

Central Diffraction at ALICE

The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment ofthe central system allows detailed QCD studies and searches for exotic mesonstates, such as glueballs, hybrids and new charmonium-like states. It wouldalso provide a good testing ground for detailed studies of heavy quarkonia. Dueto its central barrel performance, ALICE can accurately measure the low-masscentral systems with good purity. The efficiency of the Forward MultiplicityDetector (FMD) and the Forward Shower Counter (FSC) system for detectingrapidity gaps is shown to be adequate for the proposed studies. With thisdetector arrangement, valuable new data can be obtained by tagging centraldiffractive processes.

Bridging East and West : The Establishment of the International Institute for Applied Systems Analysis (IIASA) in the United States Foreign Policy of Bridge Building, 1964-1972.

The dissertation examines the foreign policies of the United States through the prism of science and technology. In the focal point of scrutiny is the policy establishing the International Institute for Applied Systems Analysis (IIASA) and the development of the multilateral part of bridge building in American foreign policy during the 1960s and early 1970s. After a long and arduous negotiation process, the institute was finally established by twelve national member organizations from the following countries: Bulgaria, Canada, Czechoslovakia, Federal Republic of Germany (FRG), France, German Democratic Republic (GDR), Great Britain, Italy, Japan, Poland, Soviet Union and United States; a few years later Sweden, Finland and the Netherlands also joined. It is said that the goal of the institute was to bring together researchers from East and West to solve pertinent problems caused by the modernization process experienced in industrialized world. It originates from President Lyndon B. Johnson s bridge building policies that were launched in 1964, and was set in a well-contested and crowded domain of other international organizations of environmental and social planning. Since the distinct need for yet another organization was not evident, the process of negotiations in this multinational environment enlightens the foreign policy ambitions of the United States on the road to the Cold War détente. The study places this project within its political era, and juxtaposes it with other international organizations, especially that of the OECD, ECE and NATO. Conventionally, Lyndon Johnson s bridge building policies have been seen as a means to normalize its international relations bilaterally with different East European countries, and the multilateral dimension of the policy has been ignored. This is why IIASA s establishment process in this multilateral environment brings forth new information on US foreign policy goals, the means to achieve these goals, as well as its relations to other advanced industrialized societies before the time of détente, during the 1960s and early 1970s. Furthermore, the substance of the institute applied systems analysis illuminates the differences between European and American methodological thinking in social planning. Systems analysis is closely associated with (American) science and technology policies of the 1960s, especially in its military administrative applications, thus analysis within the foreign policy environment of the United States proved particularly fruitful. In the 1960s the institutional structures of European continent with faltering, and the growing tendencies of integration were in flux. One example of this was the long, drawn-out process of British membership in the EEC, another is de Gaulle s withdrawal from NATO s military-political cooperation. On the other hand, however, economic cooperation in Europe between East and West, and especially with the Soviet Union was expanding rapidly. This American initiative to form a new institutional actor has to be seen in that structural context, showing that bridge building was needed not only to the East, but also to the West. The narrative amounts to an analysis of how the United States managed both cooperation and conflict in its hegemonic aspirations in the emerging modern world, and how it used its special relationship with the United Kingdom to achieve its goals. The research is based on the archives of the United States, Great Britain, Sweden, Finland, and IIASA. The primary sources have been complemented with both contemporary and present day research literature, periodicals, and interviews.

Public and private technical assistance programs for non-industrial private forest landowners in the southern United States.

XVIII IUFRO World Congress, Ljubljana 1986.