A String Theory Which Isn't About Strings

Quantization of closed string proceeds with a suitable choice of worldsheet vacuum. A priori, the vacuum may be chosen independently for left-moving and right-moving sectors. We construct {\sl ab initio} quantized bosonic string theory with left-right asymmetric worldsheet vacuum and explore its consequences and implications. We critically examine the validity of new vacuum and carry out first-quantization using standard operator formalism. Remarkably, the string spectrum consists only of a finite number of degrees of freedom: string gravity (massless spin-two, Kalb-Ramond and dilaton fields) and two massive spin-two Fierz-Pauli fields. The massive spin-two fields have negative norm, opposite mass-squared, and provides a Lee-Wick type extension of string gravity. We compute two physical observables: tree-level scattering amplitudes and one-loop cosmological constant. Scattering amplitude of four dilatons is shown to be a rational function of kinematic invariants, and in $D=26$ factorizes into contributions of massless spin-two and a pair of massive spin-two fields. The string one loop partition function is shown to perfectly agree with one loop Feynman diagram of string gravity and two massive spin-two fields. In particular, it does not exhibit modular invariance. We critically compare our construction with recent studies and contrast differences.Comment: 42 pages, 1 figure, minor corrections, references added; v3: minor corrections, references added, published version in JHE

A zinc finger protein array for the visual detection of specific DNA sequences for diagnostic applications.

The visual detection of specific double-stranded DNA sequences possesses great potential for the development of diagnostics. Zinc finger domains provide a powerful scaffold for creating custom DNA-binding proteins that recognize specific DNA sequences. We previously demonstrated sequence-enabled reassembly of TEM-1 β-lactamase (SEER-LAC), a system consisting of two inactive fragments of β-lactamase each linked to engineered zinc finger proteins (ZFPs). Here the SEER-LAC system was applied to develop ZFP arrays that function as simple devices to identify bacterial double-stranded DNA sequences. The ZFP arrays provided a quantitative assay with a detection limit of 50 fmol of target DNA. The method could distinguish target DNA from non-target DNA within 5 min. The ZFP arrays provided sufficient sensitivity and high specificity to recognize specific DNA sequences. These results suggest that ZFP arrays have the potential to be developed into a simple and rapid point-of-care (POC) diagnostic for the multiplexed detection of pathogens

Exploring Satisfaction with and Trust in Social Networking Sites through the Lens of Fan Pages: Uncertainty Reduction and General Systems Theory Perspective

The purpose of this study is to examine social networking sites (SNS) users’ overall satisfaction with and trust in SNS, as related to their activities of visiting fan pages. We employ two theories—uncertainty reduction theory (URT) and general systems theory (GST)—to examine antecedents affecting overall satisfaction with and trust in SNS. Using a web-based survey, we analyzed 200 SNS users who follow at least one company’s fan page, and utilized seemingly unrelated regression (SUR) models to empirically test our hypotheses. Our findings indicate that uncertainty reduction strategies supported by URT are significantly associated with perceived usefulness of companies’ posts in their fan pages. In turn, perceived usefulness of those posts promotes more visits to the fan page. Finally, users’ perceived usefulness of fan page posts eventually accounts for the overall satisfaction with and trust in SNS. The implications and limitations are discussed at the end of this study

Anomalous Transmission Phase of a Kondo-Correlated Quantum Dot

We study phase evolution of transmission through a quantum dot with Kondo correlations. By considering a model that includes nonresonant transmission as well as the Anderson impurity, we explain unusually large phase evolution of about $\pi$ in the Kondo valley observed in recent experiments. We argue that this anomalous phase evolution is a universal property that can be found in the high-temperature Kondo phase in the presence of the time-reversal symmetry.Comment: 5 pages, 3 figure

Total Reflection and Negative Refraction of Dipole-Exchange Spin Waves at Magnetic Interfaces: Micromagnetic Modeling Study

We demonstrated that dipole-exchange spin waves traveling in geometrically restricted magnetic thin films satisfy the same laws of reflection and refraction as light waves. Moreover, we found for the first time novel wave behaviors of dipole-exchange spin waves such as total reflection and negative refraction. The total reflection in laterally inhomogeneous thin films composed of two different magnetic materials is associated with the forbidden modes of refracted dipole-exchange spin waves. The negative refraction occurs at a 90 degree domain-wall magnetic interface that is introduced by a cubic magnetic anisotropy in the media, through the anisotropic dispersion of dipole-exchange spin waves.Comment: 13 pages, 5 figure

Chiral magnetoresistance in Pt/Co/Pt zigzag wires

The Rashba effect leads to a chiral precession of the spins of moving electrons while the Dzyaloshinskii-Moriya interaction (DMI) generates preference towards a chiral profile of local spins. We predict that the exchange interaction between these two spin systems results in a 'chiral' magnetoresistance depending on the chirality of the local spin texture. We observe this magnetoresistance by measuring the domain wall (DW) resistance in a uniquely designed Pt/Co/Pt zigzag wire, and by changing the chirality of the DW with applying an in-plane magnetic field. A chirality-dependent DW resistance is found, and a quantitative analysis shows a good agreement with a theory based on the Rashba model. Moreover, the DW resistance measurement allows us to independently determine the strength of the Rashba effect and the DMI simultaneously, and the result implies a possible correlation between the Rashba effect, the DMI, and the symmetric Heisenberg exchange

The Effects of d_{x^2-y^2}-d_{xy} Mixing on Vortex Structures and Magnetization

The structure of an isolated single vortex and the vortex lattice, and the magnetization in a $d$-wave superconductor are investigated within a phenomenological Ginzburg-Landau (GL) model including the mixture of the $d_{x^2-y^2}$-wave and $d_{xy}$-wave symmetry. The isolated single vortex structure in a week magnetic field is studied both numerically and asymptotically. Near the upper critical field $H_{c2}$, the vortex lattice structure and the magnetization are calculated analytically.Comment: 14 pages, REVTeX, 2 EPS figures, Journal of Physics: Condensed Matter (in press