Tkachenko modes and structural phase transitions of the vortex lattice of a two component Bose-Einstein condensate

We consider a rapidly rotating two-component Bose-Einstein condensate (BEC) containing a vortex lattice. We calculate the dispersion relation for small oscillations of vortex positions (Tkachenko modes) in the mean-field quantum Hall regime, taking into account the coupling of these modes with density excitations. Using an analytic form for the density of the vortex lattice, we numerically calculate the elastic constants for different lattice geometries. We also apply this method to calculate the elastic constant for the single-component triangular lattice. For a two-component BEC, there are two kinds of Tkachenko modes, which we call acoustic and optical in analogy with phonons. For all lattice types, acoustic Tkachenko mode frequencies have quadratic wave-number dependence at long-wavelengths, while the optical Tkachenko modes have linear dependence. For triangular lattices the dispersion of the Tkachenko modes are isotropic, while for other lattice types the dispersion relations show directional dependence consistent with the symmetry of the lattice. Depending on the intercomponent interaction there are five distinct lattice types, and four structural phase transitions between them. Two of these transitions are second-order and are accompanied by the softening of an acoustic Tkachenko mode. The remaining two transitions are first-order and while one of them is accompanied by the softening of an optical mode, the other does not have any dramatic effect on the Tkachenko spectrum. We also find an instability of the vortex lattice when the intercomponent repulsion becomes stronger than the repulsion within components.Comment: 24 pages, 13 figures, typos corrected, references added, final versio

POWER AND PERFORMANCE STUDIES OF THE EXPLICIT MULTI-THREADING (XMT) ARCHITECTURE

Power and thermal constraints gained critical importance in the design of microprocessors over the past decade. Chipmakers failed to keep power at bay while sustaining the performance growth of serial computers at the rate expected by consumers. As an alternative, they turned to fitting an increasing number of simpler cores on a single die. While this is a step forward for relaxing the constraints, the issue of power is far from resolved and it is joined by new challenges which we explain next. As we move into the era of many-cores, processors consisting of 100s, even 1000s of cores, single-task parallelism is the natural path for building faster general-purpose computers. Alas, the introduction of parallelism to the mainstream general-purpose domain brings another long elusive problem to focus: ease of parallel programming. The result is the dual challenge where power efficiency and ease-of-programming are vital for the prevalence of up and coming many-core architectures. The observations above led to the lead goal of this dissertation: a first order validation of the claim that even under power/thermal constraints, ease-of-programming and competitive performance need not be conflicting objectives for a massively-parallel general-purpose processor. As our platform, we choose the eXplicit Multi-Threading (XMT) many-core architecture for fine grained parallel programs developed at the University of Maryland. We hope that our findings will be a trailblazer for future commercial products. XMT scales up to thousand or more lightweight cores and aims at improving single task execution time while making the task for the programmer as easy as possible. Performance advantages and ease-of-programming of XMT have been shown in a number of publications, including a study that we present in this dissertation. Feasibility of the hardware concept has been exhibited via FPGA and ASIC (per our partial involvement) prototypes. Our contributions target the study of power and thermal envelopes of an envisioned 1024-core XMT chip (XMT1024) under programs that exist in popular parallel benchmark suites. First, we compare XMT against an area and power equivalent commercial high-end many-core GPU. We demonstrate that XMT can provide an average speedup of 8.8x in irregular parallel programs that are common and important in general purpose computing. Even under the worst-case power estimation assumptions for XMT, average speedup is only reduced by half. We further this study by experimentally evaluating the performance advantages of Dynamic Thermal Management (DTM), when applied to XMT1024. DTM techniques are frequently used in current single and multi-core processors, however until now their effects on single-tasked many-cores have not been examined in detail. It is our purpose to explore how existing techniques can be tailored for XMT to improve performance. Performance improvements up to 46% over a generic global management technique has been demonstrated. The insights we provide can guide designers of other similar many-core architectures. A significant infrastructure contribution of this dissertation is a highly configurable cycle-accurate simulator, XMTSim. To our knowledge, XMTSim is currently the only publicly-available shared-memory many-core simulator with extensive capabilities for estimating power and temperature, as well as evaluating dynamic power and thermal management algorithms. As a major component of the XMT programming toolchain, it is not only used as the infrastructure in this work but also contributed to other publications and dissertations

Options for Low-Cost Manufacturing and Safer Cell Therapies

The proposed work aims to overcome the economical and feasibility-related limitations of the chimeric antigen receptor therapies by developing an artificial cell signaling pathway whose design transforms K562 cells into in vivo living vectors to synthesize therapeutic proteins upon engaging diseased cells in the treatment of ovarian cancer. There are various advantages of using K562 cells throughout this process. First, Food and Drug Administration approves the reinfusion of K562 cells into patients’ bodies. Second, K562 cells are more affordable than T lymphocytes, and finally, these cells can be easily manipulated with any desired genetic material and can keep the expression of engineered genes stable. However, they do not express a chemokine receptor, a type of cytokine controlling the traffic of the immune cells to a desired site of the body. Therefore, these cells must be manipulated with chemokine receptors to enable them to migrate directly towards the tumor microenvironment to prevent harm to the healthy parts of the body. For the manipulation of all cells used in this study, lentiviruses were produced to transduce them. Nanoluc luciferase reporter was used as an effector protein to evaluate whether K562 cells can synthesize these enzymes in situ upon interacting with diseased cells. K562 cells lack necessary molecules that would drive them to form an immunological synapse to produce engineered proteins. As a result, they were not able to produce the Nanoluc enzyme. On the other hand, this study shows that the chemokine system presents an excellent potential for immunotherapies, and it may help prevent damage to healthy tissue

Establishing a new protection and indemnity (P&I) insurance institution in Turkey

Insurance draws attention as a sector that is understood much better in terms of its importance especially in recent years globally and in Turkey as well and this sector is developing each day. In direct proportion to the development of insurance, the importance of marine insurance forming a special part of insurance has also come to the surface. Marine insurance, as a field has unique characteristics that can dominant from general insurance principles from certain angles, and stands before us as a dynamic field necessary to be reviewed and handled over and over again with the developments in the world. In Turkey, there have been various studies related to some of the fields of marine insurance. In this dissertation, components of Protection and Indemnity Insurance will be dealt with comprehensively. Furthermore, problems and solution methods associated with club insurance practices are addressed

Higgs(es) in triplet extended supersymmetric standard model at the LHC

Volume: 273-275The recent discovery of the 125 GeV Higgs boson by Atlas and CMS experiments has set strong constraints on parameter space of the minimal supersymmetric model (MSSM). However these constraints can be weakened by enlarging the Higgs sector by adding a triplet chiral superfield. In particular, we focus on the Y = 0 triplet extension of MSSM, known as TESSM, where the electroweak contributions to the lightest Higgs mass are also important and comparable with the strong contributions. We discuss this in the context of the observed Higgs like particle around 125 GeV and also look into the status of other Higgs bosons in the model. We calculate the Br(B-s -> X-s gamma) in this model where three physical charged Higgs bosons and three charginos contribute. We show that the doublet-triplet mixing in charged Higgses plays an important role in constraining the parameter space. In this context we also discuss the phenomenology of light charged Higgs probing H-1(+/-) - W--/+ - Z coupling at the LHC.Peer reviewe