Homologous chromosomes display associations in many organisms. Drosophila melanogaster (here after, Drosophila) serves as an excellent model to study pairing interactions since chromosomes are paired in all somatic cells throughout development. For many genes, the degree of homolog association influences gene expression. These effects, collectively referred to as transvection, can promote gene activation or silencing. Requirements for transvection are poorly understood. Chapter One reviews what is known about transvection in Drosophila and chromosome interactions in mammals. Recent cell culture studies implicated a requirement for Topoisomerase 2 (Top2) in chromosome pairing. Top2 encodes an ATP dependent homodimeric enzyme that generates double stranded breaks to change DNA topology. This enzyme is a common target of anticancer drugs due to its role in DNA metabolism. To understand the in vivo role of Drosophila Top2, an EMS screen was completed. Chapter Two describes the identification and characterization of fifteen new EMS generated Top2 mutations. Fifteen null and hypomorphic alleles were obtained, including one that displays temperature sensitivity. Molecular analyses of these alleles uncovered single or multiple base pair substitutions within the coding region of each mutant gene. Even though flies carrying individual missense alleles in trans to a deficiency are inviable, heteroallelic combinations of several missense alleles produced viable flies, including two lines carrying mutations that display resistance to anti-cancer drugs. These data indicate that Top2 activity can be restored by dimerization of defective subunits. Our new Top2 alleles establish a novel allelic series and provide a platform for understanding drug resistance. In Chapter Three, the role of Top2 in chromosome associations was tested to determine whether mutations in Top2 disrupted transvection. Viable heteroallelic combinations of Top2 mutations were used to test transvection at three classically studied loci. For each gene, homologous interactions were analyzed by screening for alterations in pairing-dependent changes in phenotype involving transvecting alleles. Only one of the three genes tested displayed phenotypic changes in Top2 complementing adults that were consistent with an alteration in pairing dependent changes in expression. Transcript levels were assessed at the three genes studied that display transvection. Our studies indicate that changes in the phenotype, due to altered Top2, are likely gene specific transcriptional changes. Further investigation of gene associations in Top2 mutants employed fluorescence in situ hybridization (FISH). These studies showed that all loci examined were paired near wild type levels, suggesting that Top2 does not globally disrupt homolog associations in vivo. The differences observed in Top2 function in vivo and in vitro may be explained by two possibilities. First, the probes studied differ from those used in vitro, indicating that different genetic loci may have different sensitivities to unpairing. Second, Top2 plays a role in the segregation of sister chromatids during anaphase and loss of Top2 causes improper resolution of chromosomes resulting in aneuploidy. In cell culture, cells were allowed to go through one division and then were subsequently fixed, permitting analyses on all cells. It is possible that nuclei exhibiting aneuploidy have undergone cell death in vivo, explaining why we do not see increased amounts of unpairing. In conclusion, Top2 contributions to nuclear functions are complex. Loss of Top2 may result in subtle changes in pairing that may affect transcription and transvection.

<p> A study is made of the effects of pairing of defects on the dynamics of impure lattices, with the prospect of calculating the properties of crystals with a reasonably high concentration of impurities. A harmonic theory is used, with a mass-defect model, i.e. mass differences only are considered.</p> <p> Various parameters of lattice dynamics are studied, such as the atomic mean square displacement, by use of the Green's functions of Zubarev (1960), as evaluated by Bruno (1971).</p> <p> Finally, a calculation is made of the shifts and widths in the phonon spectrum of Copper due to the addition of 20% Gold impurities. The theory of Aiyer et al. (1969) is used, as corrected by Nickel and Krumhansl (1971), with a derivation along the lines of Langer (1961).</p> <p> It is shown that pairing effects are small and that the high-concentration calculation does not reproduce the experimental results of Svensson and Kamitakahara (1972) so that a more detailed model must be employed, in particular the inclusion of force constant changes and volume effects appears to be necessary.</p> / Thesis / Master of Science (MSc)

Bilinear pairings are being used in ingenious ways to solve various protocol problems. Much research has been done on improving the efficiency of pairing computations. This thesis gives an introduction to the Tate pairing and some variants including the ate pairing, Vercauteren's pairing, and the R-ate pairing. We describe the Barreto-Naehrig (BN) family of pairing-friendly curves, and analyze three different coordinates systems (affine, projective, and jacobian) for implementing the R-ate pairing. Finally, we examine some recent work for speeding the pairing computation and provide improved estimates of the pairing costs on a particular BN curve.

Bilinear pairings are being used in ingenious ways to solve various protocol problems. Much research has been done on improving the efficiency of pairing computations. This thesis gives an introduction to the Tate pairing and some variants including the ate pairing, Vercauteren's pairing, and the R-ate pairing. We describe the Barreto-Naehrig (BN) family of pairing-friendly curves, and analyze three different coordinates systems (affine, projective, and jacobian) for implementing the R-ate pairing. Finally, we examine some recent work for speeding the pairing computation and provide improved estimates of the pairing costs on a particular BN curve.

Maintenance of an intact genome and proper regulation of the genes within are crucial aspects for life. The work of this dissertation has implicated the Drosophila condensin II complex in both processes. Condensin II's ability to reconfigure chromosomes into spatially separated and discrete units is necessary to ensure proper meiotic segregation. When this "individualization" activity fails in a condensin II mutant, chromosomes remain entangled, and either cosegregate or become lost during cell division. This leads to the creation of aneuploid sperm. We have also implicated condensin II as a factor necessary to individualize interphase somatic chromosomes from one another. This is relevant in Drosophila because the association of homologous chromosomes is thought to facilitate gene regulation activity in trans. We speculate that condensin II individualization spatially distances aligned chromosomes from one another and prevents this trans-communication between allelic loci. This is supported first by an increase of homologous chromosome pairing in a condensin II mutant background. Secondly, loss of condensin II leads to elevated production from alleles that are known to depend on pairing for transcriptional activation. These meiotic and interphase condensin II roles support its necessity to Drosophila genome integrity and transcriptional regulation. Given the conservation of condensin from bacteria to humans, it is likely that equivalent or related roles exist in a variety of species.

Mobile applications can benefit from increased awareness of the device's context. Unfortunately, existing solutions for inferring context require special purpose sensors or beacons on the mobile devices or in the physical environment. This requirement significantly limits the deployment of these solutions. In this thesis, I argue that mobile devices can infer a substantial amount of their context by leveraging their existing wireless interfaces to monitor ambient radio sources, such as GSM cell towers or WiFi access points. I focus on two important problems in context-aware computing: localization of mobile devices and detecting proximity between mobile devices for authentication purposes. Specifically, I present an accurate localization system based on fingerprinting of GSM signals. I show that the key to more accurate GSM localization is the use of wide signal strength fingerprints that include readings from a large number of base stations. Next, I present a method that addresses the key drawback of fingerprint-based localization systems - the need to collect extensive measurements to train the system in every target environment. Finally, I show how radio environment sensing can be used to secure the communication of devices that come within close proximity. Removing the need for additional hardware on the mobile devices and in the physical environment renders the approach that I present amenable for widespread deployment.

It was recently discovered by Joux [30] and Sakai, Ohgishi and Kasahara [47] that bilinear maps could be used to construct cryptographic schemes. Since then, bilinear maps have been used in applications as varied as identity-based encryption, short signatures and one-round tripartite key agreement. This thesis explains the notion of bilinear maps and surveys the applications of bilinear maps in the three main fields of cryptography: encryption, signature and key agreement. We also show how these maps can be constructed using the Weil and Tate pairings in elliptic curves.

Philosophiae Doctor - PhD / This thesis describes research work undertaken to study neutron pairing correlations in 136Ba via the 138Ba(p, t) pair transfer reaction and to perform high-precision spectroscopy of low-lying states in 136Cs using the 138Ba(d, ) reaction. The aim of this project was to provide useful spectroscopic information relevant for matrix element calculations of 136Xe neutrinoless double beta decay. This work is relevant because neutrinoless double beta decays are standard-model-forbidden lepton number violating processes, which if observed, would establish the Majorana nature of the neutrinos and also determine the absolute mass scale of the light Majorana neutrinos. Our experiments show a signi cant fragmentation of the two-neutron transfer (p, t) strength to excited 0+ states in 136Ba, which could signi cantly affect future matrix element calculations. Additionally we obtain information on 65 new states in 136Cs observed in this work. It is anticipated that these new information will play a vital role in improving the precision of calculated matrix elements for 136Xe double beta decays.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / Ph.D.

Chung, Chun Kit = 超低溫相互作用費米原子中配對的探究 / 鍾俊傑. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 81-88). / Abstracts in English and Chinese. / Chung, Chun Kit = Chao di wen xiang hu zuo yong fei mi yuan zi zhong pei dui de tan jiu / Zhong Junjie. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Review on BCS theory --- p.4 / Chapter 2.1 --- BCS theory in uniform systems --- p.4 / Chapter 2.1.1 --- Hamiltonian and ground state solutions --- p.4 / Chapter 2.1.2 --- Choice of interaction potential --- p.7 / Chapter 2.1.3 --- Uniform atomic gas at T = 0 --- p.9 / Chapter 2.2 --- Self-consistent field method --- p.13 / Chapter 2.2.1 --- Population imbalanced systems --- p.17 / Chapter 2.3 --- Description of BCS states at finite temperatures --- p.22 / Chapter 3 --- Bipartite quantum entanglement in BCS states --- p.25 / Chapter 3.1 --- Mixed state bipartite quantum entanglement --- p.26 / Chapter 3.1.1 --- PPT criterion --- p.27 / Chapter 3.1.2 --- Negativity of p --- p.28 / Chapter 3.1.3 --- Entanglement witness --- p.30 / Chapter 3.1.4 --- Two-particle density matrix and two-body negativity --- p.30 / Chapter 3.2 --- Opposite spin states as subsystems --- p.31 / Chapter 3.2.1 --- Structure of and the negativity --- p.32 / Chapter 3.2.2 --- Relationship between the negativity and the order pa- rameter --- p.33 / Chapter 3.2.3 --- Distribution of negative eigenvalues of --- p.34 / Chapter 3.2.4 --- Constructing entanglement witness operator --- p.35 / Chapter 3.2.5 --- Remark: Same spin state as subsystems --- p.37 / Chapter 3.3 --- Momentum states as subsystems --- p.40 / Chapter 3.3.1 --- A and B as opposite momentum states --- p.41 / Chapter 3.3.2 --- A and B as different momentum states k and k' with k≠± k' --- p.43 / Chapter 3.3.3 --- A and B as the same momentum state --- p.44 / Chapter 3.4 --- Summary --- p.45 / Chapter 4 --- Radio-frequency spectroscopy --- p.47 / Chapter 4.1 --- The model Hamiltonian and dynamical equations --- p.49 / Chapter 4.1.1 --- Time-dependent variational method --- p.50 / Chapter 4.1.2 --- Time-dependent Bogoliubov-de Gennes equations --- p.51 / Chapter 4.2 --- Short-time dynamics --- p.53 / Chapter 4.2.1 --- Eigenvectors and Eigenvalues of C --- p.54 / Chapter 4.2.2 --- Build up of particle number density n3 and order param- eter Δ23 --- p.57 / Chapter 4.3 --- Summary --- p.61 / Chapter 5 --- Pairing in three-component systems --- p.63 / Chapter 5.1 --- The mean-field Hamiltonian --- p.64 / Chapter 5.2 --- Symmetric systems --- p.67 / Chapter 5.2.1 --- Quasiparticle spectra --- p.68 / Chapter 5.2.2 --- "Occupation number, condensation amplitude, and co- herence amplitude" --- p.70 / Chapter 5.2.3 --- Strengths of Ω --- p.71 / Chapter 5.3 --- Pairing in asymmetric systems --- p.73 / Chapter 5.3.1 --- Quasiparticle spectra and mean-field solutions --- p.73 / Chapter 5.3.2 --- Effects of Ωij --- p.74 / Chapter 5.4 --- Summary --- p.76 / Chapter 6 --- Conclusion and outlook --- p.79 / Bibliography --- p.81 / Chapter A --- Regularization techniques --- p.89 / Chapter B --- Wick's theorem --- p.91 / Chapter C --- Analytic solutions to three-component symmetric systems --- p.94