Semiclassical and Quantum Field Theoretic Bounds for Traversable Lorentzian Stringy Wormholes

A lower bound on the size of a Lorentzian wormhole can be obtained by semiclassically introducing the Planck cut-off on the magnitude of tidal forces (Horowitz-Ross constraint). Also, an upper bound is provided by the quantum field theoretic constraint in the form of the Ford-Roman Quantum Inequality for massless minimally coupled scalar fields. To date, however, exact static solutions belonging to this scalar field theory have not been worked out to verify these bounds. To fill this gap, we examine the wormhole features of two examples from the Einstein frame description of the vacuum low energy string theory in four dimensions which is the same as the minimally coupled scalar field theory. Analyses in this paper support the conclusion of Ford and Roman that wormholes in this theory can have sizes that are indeed only a few order of magnitudes larger than the Planck scale. It is shown that the two types of bounds are also compatible. In the process, we point out a "wormhole" analog of naked black holes.Comment: 15 page

All Data are Wrong, but Some are Useful? Advocating the Need for Data Auditing

<p>In a recent article from the <i>Annals of Applied Statistics</i>, Cox discussed the main phases of applied statistical research ranging from clarifying study objectives to final data analysis and interpreting results. As an incidental remark to these main phases, we advocate that beyond <i>cleaning</i> and <i>preprocessing</i> the data, it is a good practice to <i>audit</i> the data to determine if they can be trusted at all. A case study based on Ghanaian Official Fishery Statistics is used to illustrate this need, with Benford's law being the tool used to carrying out the data audit. Supplementary materials for this article are available online.</p

High Power Microwave Operational Exposure Detection using Thermoacoustic Wave Generation in Lossy Dielectric Polymers

A feasibility analysis for the use of microwave-induced thermoacoustic (TA) wave generation in lossy dielectric media to detect pulsed high power microwave directed energy weapons in force health protection applications was conducted based on a series of empirical and computational investigations. A potential target volume material, carbon-loaded polytetrafluoroethylene, was identified for further study based on anticipated complex dielectric properties, with laboratory measurements of select electromagnetic (EM), thermal, and elastic material properties of relevance to the TA effect conducted to determine parameter values. A planar geometry TA-based signal chain model using thin film piezoelectric sensors was developed for both finite element method based numerical simulation and in-beam response testing, with TA signal output evaluated in the time and frequency domain using both approaches. Based on empirically-derived complex permittivity values, a single-term Cole-Cole dielectric relaxation model approximation was developed over the 2-110 GHz microwave frequency region to permit a more general evaluation of EM coupling efficiency of the material. Modeling and simulation of the idealized signal chain allowed the analysis of TA waveform dependency on microwave beam parameters not otherwise accessible during in-beam response testing. High frequency TA signal data was suitably fit to a pulse width sensitivity impulse response function model for the target geometry and found to be in good agreement for personnel exposure applications

Mid-infrared Selection of Active Galactic Nuclei with the Wide-Field Infrared Survey Explorer. I. Characterizing WISE-selected Active Galactic Nuclei in COSMOS

The Wide-field Infrared Survey Explorer (WISE) is an extremely capable and efficient black hole finder. We present a simple mid-infrared color criterion, W1 – W2 ≥ 0.8 (i.e., [3.4]–[4.6] ≥0.8, Vega), which identifies 61.9 ± 5.4 active galactic nucleus (AGN) candidates per deg^2 to a depth of W2 ~ 15.0. This implies a much larger census of luminous AGNs than found by typical wide-area surveys, attributable to the fact that mid-infrared selection identifies both unobscured (type 1) and obscured (type 2) AGNs. Optical and soft X-ray surveys alone are highly biased toward only unobscured AGNs, while this simple WISE selection likely identifies even heavily obscured, Compton-thick AGNs. Using deep, public data in the COSMOS field, we explore the properties of WISE-selected AGN candidates. At the mid-infrared depth considered, 160 μJy at 4.6 μm, this simple criterion identifies 78% of Spitzer mid-infrared AGN candidates according to the criteria of Stern et al. and the reliability is 95%. We explore the demographics, multiwavelength properties and redshift distribution of WISE-selected AGN candidates in the COSMOS field