High-rate, Single-Symbol Decodable Distributed STBCs for Partially-Coherent Cooperative Networks

Space-time block codes (STBCs) that are single-symbol decodable (SSD) in a co-located multiple antenna setting need not be SSD in a distributed cooperative communication setting. A relay network with N relays and a single source-destination pair is called a partially-coherent relay channel (PCRC) if the destination has perfect channel state information (CSI) of an the channels and the relays have only the phase information of the source-to-relay channels. In our earlier work, we had derived a set of necessary and sufficient conditions for a distributed STBC (DSTBC) to be SSD for a PCRC. Using these conditions, in this paper we show that the possibility of channel phase compensation operation at the relay nodes using partial CSI at the relays increases the possible rate of SSD DSTBCs from 2/N when the relays do not have CSI to 1/2, which is independent of N. We also show that when a DSTBC is SSD for a PCRC, then arbitrary coordinate interleaving of the in-phase and quadrature-phase components of the variables does not disturb its SSD property. Using this property we are able to construct codes that are SSD and have higher rate than 2/N but giving full diversity only for signal constellations satisfying certain conditions.

Exotic superfluid states of ultra-cold Fermi gases

This is a study of ultra-cold Fermi gases in different systems. This thesis is focused on exotic superfluid states, for an example on the three component Fermi gas and the FFLO phase in optical lattices. In the two-components case, superfluidity is studied mainly in the case of the spin population imbalanced Fermi gases and the phase diagrams are calculated from the mean-field theory. Different methods to detect different phases in optical lattices are suggested. In the three-component case, we studied also the uniform gas and harmonically trapped system. In this case, the BCS theory is generalized to three-component gases. It is also discussed how to achieve the conditions to get an SU(3)-symmetric Hamiltonian in optical lattices. The thesis is divided in chapters as follows: Chapter 1 is an introduction to the field of cold quantum gases. In chapter 2 optical lattices and their experimental characteristics are discussed. Chapter 3 deals with two-components Fermi gases in optical lattices and the paired states in lattices. In chapter 4 three-component Fermi gases with and without a harmonic trap are explored, and the pairing mechanisms are studied. In this chapter, we also discuss three-component Fermi gases in optical lattices. Chapter 5 devoted to the higher order correlations, and what they can tell about the paired states. Chapter 6 concludes the thesis.

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.

Eron aika : Tyttärien kertomuksia ikääntyneen vanhemman kuolemasta

There is a relative absence of sociological and cultural research on how people deal with the death of a family member in the contemporary western societies. Research on this topic has been dominated by the experts of psychology, psychiatry and therapy, who mention the social context only in passing, if at all. This gives an impression that the white westerners bereavement experience is a purely psychological phenomenon, an inner journey, which follows a natural, universal path. Yet, as Tony Walter (1999) states, ignoring the influence of culture not only impoverishes the understanding of those work with bereaved people, but it also impoverishes sociology and cultural studies by excluding from their domain a key social phenomenon. This study explores the cultural dimension of grief through narratives told by fifteen of recently bereaved Finnish women. Focussing on one sex only, the study rests on the assumption of the gendered nature of bereavement experience. However, the aim of the study is not to pinpoint the gender differences in grief and mourning, but to shed light on women s ways of dealing with the loss of a loved one in a social context. Furthermore, the study focuses on a certain kind of loss: the death of an elderly parent. Due to the growth in the life expectancy rate, this has presumably become the most typical type of bereavement in contemporary, ageing societies. Most of population will face the death of a parent as they reach the middle years of the life course. The data of this study is gathered with interviews, in which the interviewees were invited to tell a narrative of their bereavement. Narrative constitutes a central concept in this study. It refers to a particular form of talk, which is organised around consequential events. But there are also other, deeper layers that have been added to this concept. Several scholars see narratives as the most important way in which we make sense of experience. Personal narratives provide rich material for mapping the interconnections between individual and culture. As a form of thought, narrative marries singular circumstances with shared expectations and understandings that are learned through participation in a specific culture (Garro & Mattingly 2000). This study attempts to capture the cultural dimension of narrative with the concept of script , which originates in cognitive science (Schank & Abelson 1977) and has recently been adopted to narratology (Herman 2002). Script refers to a data structure that informs how events usually unfold in certain situations. Scripts are used in interpreting events and representing them verbally to others. They are based on dominant forms of knowledge that vary according to time and place. The questions that were posed in this study are the following. What kind of experiences bereaved daughters narrate? What kind of cultural scripts they employ as they attempt to make sense of these experiences? How these scripts are used in their narratives? It became apparent that for the most of the daughters interviewed in this study the single most important part of the bereavement narrative was to form an account of how and why the parent died. They produced lengthy and detailed descriptions of the last stage of a parent s life in contrast with the rest of the interview. These stories took their start from a turn in the parent s physical condition, from which the dying process could in retrospect be seen to have started, and which often took place several years before the death. In addition, daughters also talked about their grief reactions and how they have adjusted to a life without the deceased parent. The ways in which the last stage of life was told reflect not only the characteristic features of late modernity but also processes of marginalisation and exclusion. Revivalist script and medical script, identified by Clive Seale as the dominant, competing models for dying well in the late modern societies, were not widely utilised in the narratives. They could only be applied in situations in which the parent had died from cancer and at somewhat younger age than the average. Death that took place in deep old age was told in a different way. The lack of positive models for narrating this kind of death was acknowledged in the study. This can be seen as a symptom of the societal devaluing of the deaths of older people and it affects also daughters accounts of their grief. Several daughters told about situations in which their loss, although subjectively experienced, was nonetheless denied by other people.

Multiple conformational states in crystals and in solution in alpha gamma hybrid peptides. Fragility of the C-12 helix in short sequences

The conformational properties of foldamers generated from alpha gamma hybrid peptide sequences have been probed in the model sequence Boc-Aib-Gpn-Aib-Gpn-NHMe. The choice of alpha-aminoisobutyryl (Aib) and gabapentin (Gpn) residues greatly restricts sterically accessible coil formational space. This model sequence was anticipated to be a short segment of the alpha gamma C-12 helix, stabilized by three successive 4 -> 1 hydrogen bonds, corresponding to a backbone-expanded analogue of the alpha polypeptide 3(10)-helix. Unexpectedly, three distinct crystalline polymorphs were characterized in the solid state by X-ray diffraction. In one form, two successive C-12 hydrogen bonds were obtained at the N-terminus, while a novel C-17 hydrogen-bonded gamma alpha gamma turn was observed at the C-terminus. In the other two polymorphs, isolated C-9 and C-7 hydrogen-bonded turns were observed at Gpn (2) and Gpn (4). Isolated C-12 and C-9 turns were also crystallographically established in the peptides Boc-Aib-Gpn-Aib-OMe and Boc-Gpn-Aib-NHMe, respectively. Selective line broadening of NH resonances and the observation of medium range NH(i)<-> NH(i+2) NOEs established the presence of conformational heterogeneity for the tetrapeptide in CDCl3 solution. The NMR results are consistent with the limited population of the continuous C-12 helix conformation. Lengthening of the (alpha gamma)(n) sequences in the nonapeptides Boc-Aib-Gpn-Aib-Gpn-Aib-Gpn-Aib-Gpn-Xxx (Xxx = Aib, Leu) resulted in the observation of all of the sequential NOEs characteristic of an alpha gamma C-12 helix. These results establish that conformational fragility is manifested in short hybrid alpha gamma sequences despite the choice of conformationally constrained residues, while stable helices are formed on chain extension.

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.

Coherent quantum Boltzmann equations from cQPA

We reformulate and extend our recently introduced quantum kinetic theory for interacting fermion and scalar fields. Our formalism is based on the coherent quasiparticle approximation (cQPA) where nonlocal coherence information is encoded in new spectral solutions at off-shell momenta. We derive explicit forms for the cQPA propagators in the homogeneous background and show that the collision integrals involving the new coherence propagators need to be resummed to all orders in gradient expansion. We perform this resummation and derive generalized momentum space Feynman rules including coherent propagators and modified vertex rules for a Yukawa interaction. As a result we are able to set up self-consistent quantum Boltzmann equations for both fermion and scalar fields. We present several examples of diagrammatic calculations and numerical applications including a simple toy model for coherent baryogenesis.

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.

Svetlichny's inequality and genuine tripartite nonlocality in three-qubit pure states

The violation of the Svetlichny's inequality (SI) [Phys. Rev. D 35, 3066 (1987)] is sufficient but not necessary for genuine tripartite nonlocal correlations. Here we quantify the relationship between tripartite entanglement and the maximum expectation value of the Svetlichny operator (which is bounded from above by the inequality) for the two inequivalent subclasses of pure three-qubit states: the Greenberger-Horne-Zeilinger (GHZ) class and the W class. We show that the maximum for the GHZ-class states reduces to Mermin's inequality [Phys. Rev. Lett. 65, 1838 (1990)] modulo a constant factor, and although it is a function of the three tangle and the residual concurrence, large numbers of states do not violate the inequality. We further show that by design SI is more suitable as a measure of genuine tripartite nonlocality between the three qubits in the W-class states,and the maximum is a certain function of the bipartite entanglement (the concurrence) of the three reduced states, and only when their sum attains a certain threshold value do they violate the inequality.

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|

Non-destructive discrimination of Bell states by NMR using a single ancilla qubit

Discrimination of Bell states plays an important role in a number of quantum computational protocols such as teleportation and secret sharing. However, most of the protocols dealing with Bell state discrimination in the literature either involve performing correlated measurements or destroying the entanglement of the system. Here, we demonstrate an NMR-based experimental realization of a protocol for Bell state discrimination, following a scheme proposed by Gupta et al (quant-ph/0504183v1, 23 April 2005), which does not destroy the Bell state under consideration. Using the proposed protocol, one can deterministically distinguish the Bell states, without performing a measurement using the entangled basis. State discrimination is performed through two independent measurements on one ancilla qubit, which leaves the Bell states unchanged.

Excited-state structures of molecules with nearby electronic states

Vibronic coupling among the nearby excited electronic states via the in-plane and the out-of-plane nuclear motions is examined in benzene, pyrazine, formaldehyde and thioformaldehyde. Results reveal that in benzene the structure distorts via the most active nuclear bending (planar) motion while in the other molecules the structures distort through an out-of-plane bending motion in their respective lowest excited states.