Exploratory Study on Users’ Behavior: Smartphone Usage

Communication technologies have advanced at unprecedented rates each year. Together with these advances in technology,the Smartphone has emerged and has experienced a dramatic increase in worldwide use. In fact, Smartphones have becomethe “all-in-one” device or the “Swiss army knife” as they provide mobile access to voice, video, data, and imagecommunications. Even though Smartphones have brought many challenges, the advantages appear to far outweigh thedisadvantages. The purpose of this research in progress is to explore what motivates individuals to use Smartphones. Throughexploration using both qualitative and quantitative research techniques, this study will categorize current Smartphone usageand examine usage differences between age groups, gender, experience, and other constructs

Fuzzy BIon

We construct a solution of the BFSS matrix theory, which is a counterpart of the BIon solution representing a fundamental string ending on a bound state of a D2-brane and D0-branes. We call this solution the `fuzzy BIon' and show that this configuration preserves 1/4 supersymmetry of type IIA superstring theory. We also construct an effective action for the fuzzy BIon by analyzing the nonabelian Born-Infeld action for D0-branes. When we take the continuous limit, with some conditions, this action coincides with the effective action for the BIon configuration.Comment: 11 pages, 1 figure, reference and note adde

Generalized Kaehler Potentials from Supergravity

We consider supersymmetric N=2 solutions with non-vanishing NS three-form. Building on worldsheet results, we reduce the problem to a single generalized Monge-Ampere equation on the generalized Kaehler potential K recently interpreted geometrically by Lindstrom, Rocek, Von Unge and Zabzine. One input in the procedure is a holomorphic function w that can be thought of as the effective superpotential for a D3 brane probe. The procedure is hence likely to be useful for finding gravity duals to field theories with non-vanishing abelian superpotential, such as Leigh-Strassler theories. We indeed show that a purely NS precursor of the Lunin-Maldacena dual to the beta-deformed N=4 super-Yang-Mills falls in our class.Comment: "38 pages. v3: improved exposition and minor mistakes corrected in sec. 4

Supergravity Solutions for BI Dyons

We construct partially localized supergravity counterpart solutions to the 1/2 supersymmetric non-threshold and the 1/4 supersymmetric threshold bound state BI dyons in the D3-brane Dirac-Born-Infeld theory. Such supergravity solutions have all the parameters of the BI dyons. By applying the IIA/IIB T-duality transformations to these supergravity solutions, we obtain the supergravity counterpart solutions to 1/2 and 1/4 supersymmetric BIons carrying electric and magnetic charges of the worldvolume U(1) gauge field in the Dirac-Born-Infeld theory in other dimensions.Comment: 17 pages, REVTeX, revised version to appear in Phys. Rev.

Decoupling in an expanding universe: boundary RG-flow affects initial conditions for inflation

We study decoupling in FRW spacetimes, emphasizing a Lagrangian description throughout. To account for the vacuum choice ambiguity in cosmological settings, we introduce an arbitrary boundary action representing the initial conditions. RG flow in these spacetimes naturally affects the boundary interactions. As a consequence the boundary conditions are sensitive to high-energy physics through irrelevant terms in the boundary action. Using scalar field theory as an example, we derive the leading dimension four irrelevant boundary operators. We discuss how the known vacuum choices, e.g. the Bunch-Davies vacuum, appear in the Lagrangian description and square with decoupling. For all choices of boundary conditions encoded by relevant boundary operators, of which the known ones are a subset, backreaction is under control. All, moreover, will generically feel the influence of high-energy physics through irrelevant (dimension four) boundary corrections. Having established a coherent effective field theory framework including the vacuum choice ambiguity, we derive an explicit expression for the power spectrum of inflationary density perturbations including the leading high energy corrections. In accordance with the dimensionality of the leading irrelevant operators, the effect of high energy physics is linearly proportional to the Hubble radius H and the scale of new physics L= 1/M.Comment: LaTeX plus axodraw figures. v2: minor corrections; refs added. JHEP style: 34 pages + 18 pages appendi

Strings between branes

D-brane configurations containing fundamental strings are constructed as classical solutions of Yang-Mills theory. The fundamental strings in these systems stretch between D-branes. In the case of D1-branes, this construction gives smooth (classical) resolutions of string junctions and string networks. Using a non-abelian Yang-Mills analysis of the string current, the string charge density is computed and is shown to have support in the region between the D-brane world-volumes. The 't Hooft-Polyakov monopole is analyzed using similar methods, and is shown to contain D-strings whose flux has support off the D-brane world-volume defined by the Higgs scalar field, when this field is interpreted in terms of a transverse dimension. The constructions presented here are used to give a qualitative picture of tachyon condensation in the Yang-Mills limit, where fundamental strings and lower-dimensional D-branes arise in a volume of space-time where brane-antibrane annihilation has occurred.Comment: 35 pages, 16 eps figures, JHEP style; v2: a comment adde

Superstrings on PP-Wave Backgrounds and Symmetric Orbifolds

We study the superstring theory on pp-wave background with NSNS-flux that is realized as the Penrose limit of AdS_3 x S^3 x M^4, where M^4 is T^4 or T^4/Z_2(~ K3). Quantizing this system in the covariant gauge, we explicitly construct the space-time supersymmetry algebra and the complete set of DDF operators. We analyse the spectrum of physical states by using the spectrally flowed representations of current algebra. This spectrum is classified by the ``short string sectors'' and the ``long string sectors'' as in AdS_3 string theory. The states of the latter propagate freely along the transverse plane of pp-wave background, but the states of the former do not. We compare the short string spectrum with the BPS and almost BPS states which have large R-charges in the symmetric orbifold conformal theory, which is known as the candidate of dual theory of superstrings on AdS_3 x S^3 x M^4. We show that every short string states can be embedded successfully in the single particle Hilbert space of symmetric orbifold conformal theory.Comment: Latex, 35 pages, minor change

Nonlocal Automated Comparative Static Analysis

This paper reviews work on the development of a program Nasa for the automated comparative static analysis of parameterized nonlinear systems over parameter intervals. Nasa incorporates a fast and efficient algorithm Feed for the automatic evaluation of higher-order partial derivatives, as well as an adaptive homotopy continuation algorithm for obtaining all required initial conditions. Applications are envisioned for fields such as economics where models tend to be complex and closed-form solutions are difficult to obtain