4,872 research outputs found
Non-destructive evaluation of concrete using a capacitive imaging technique : preliminary modelling and experiments
This paper describes the application of capacitive imaging to the inspection of concrete. A two-dimensional finite-element method was employed to model the electric field distribution from capacitive imaging probe, and how it interacts with concrete samples. Physical experiments with prototype capacitive imaging probes were also carried out. The proof-of-concept results indicated that the capacitive imaging technique could be used to detect cracks on the surface of concrete samples, as well as sub-surface air voids and steel reinforcement bars
Cosmic Strings from Supersymmetric Flat Directions
Flat directions are a generic feature of the scalar potential in
supersymmetric gauge field theories. They can arise, for example, from D-terms
associated with an extra abelian gauge symmetry. Even when supersymmetry is
broken softly, there often remain directions in the scalar field space along
which the potential is almost flat. Upon breaking a gauge symmetry along one of
these almost flat directions, cosmic strings may form. Relative to the standard
cosmic string picture based on the abelian Higgs model, these flat-direction
cosmic strings have the extreme Type-I properties of a thin gauge core
surrounded by a much wider scalar field profile. We perform a comprehensive
study of the microscopic, macroscopic, and observational characteristics of
this class of strings. We find many differences from the standard string
scenario, including stable higher winding mode strings, the dynamical formation
of higher mode strings from lower ones, and a resultant multi-tension scaling
string network in the early universe. These strings are only moderately
constrained by current observations, and their gravitational wave signatures
may be detectable at future gravity wave detectors. Furthermore, there is the
interesting but speculative prospect that the decays of cosmic string loops in
the early universe could be a source of ultra-high energy cosmic rays or
non-thermal dark matter. We also compare the observational signatures of
flat-direction cosmic strings with those of ordinary cosmic strings as well as
(p,q) cosmic strings motivated by superstring theory.Comment: 58 pages, 16 figures, v2. accepted to PRD, added comments about
baryogenesis and boosted decay products from cusp annihilatio
Direct Estimation of Evoked Hemoglobin Changes by Multimodality Fusion Imaging
In the last two decades, both diffuse optical tomography (DOT) and blood oxygen level dependent (BOLD)-based functional magnetic resonance imaging (fMRI) methods have been developed as noninvasive tools for imaging evoked cerebral hemodynamic changes in studies of brain activity. Although these two technologies measure functional contrast from similar physiological sources, i.e., changes in hemoglobin levels, these two modalities are based on distinct physical and biophysical principles leading to both limitations and strengths to each method. In this work, we describe a unified linear model to combine the complimentary spatial, temporal, and spectroscopic resolutions of concurrently measured optical tomography and fMRI signals. Using numerical simulations, we demonstrate that concurrent optical and BOLD measurements can be used to create cross-calibrated estimates of absolute micromolar deoxyhemoglobin changes. We apply this new analysis tool to experimental data acquired simultaneously with both DOT and BOLD imaging during a motor task, demonstrate the ability to more robustly estimate hemoglobin changes in comparison to DOT alone, and show how this approach can provide cross-calibrated estimates of hemoglobin changes. Using this multimodal method, we estimate the calibration of the 3tesla BOLD signal to be −0.55%±0.40% signal change per micromolar change of deoxyhemoglobin
CHL Dyons and Statistical Entropy Function from D1-D5 System
We give a proof of the recently proposed formula for the dyon spectrum in CHL
string theories by mapping it to a configuration of D1 and D5-branes and
Kaluza-Klein monopole. We also give a prescription for computing the degeneracy
as a systematic expansion in inverse powers of charges. The computation can be
formulated as a problem of extremizing a duality invariant statistical entropy
function whose value at the extremum gives the logarithm of the degeneracy.
During this analysis we also determine the locations of the zeroes and poles of
the Siegel modular forms whose inverse give the dyon partition function in the
CHL models.Comment: LaTeX file, 48 pages; v2: typos correcte
Mutations in the E2 glycoprotein and the 3\u27 untranslated region enhance chikungunya virus virulence in mice
Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes debilitating musculoskeletal pain and inflammation and can persist for months to years after acute infection. Although studies of humans and experimentally infected animals suggest that CHIKV infection persists in musculoskeletal tissues, the mechanisms for this remain poorly understood. To evaluate this further, we isolated CHIKV from the serum of persistently infected Rag1 -/- mice at day 28. When inoculated into naive wild-type (WT) mice, this persistently circulating CHIKV strain displayed a capacity for earlier dissemination and greater pathogenicity than the parental virus. Sequence analysis revealed a nonsynonymous mutation in the E2 glycoprotein (E2 K200R) and a deletion within the 3' untranslated region (3'-UTR). The introduction of these changes into the parental virus conferred enhanced virulence in mice, although primary tropism for musculoskeletal tissues was maintained. The E2 K200R mutation was largely responsible for enhanced viral dissemination and pathogenicity, although these effects were augmented by the 3'- UTR deletion. Finally, studies with Irf3/Irf7 -/- and Ifnar1 -/- mice suggest that the E2 K200R mutation enhances viral dissemination from the site of inoculation independently of interferon regulatory factor 3 (IRF3)-, IRF7-, and IFNAR1-mediated responses. As our findings reveal viral determinants of CHIKV dissemination and pathogenicity, their further study should help to elucidate host-virus interactions that determine acute and chronic CHIKV infection
A gorilla adenovirus-based vaccine against Zika virus induces durable immunity and confers protection in pregnancy
The teratogenic potential of Zika virus (ZIKV) has made the development of an effective vaccine a global health priority. Here, we generate two gorilla adenovirus-based ZIKV vaccines that encode for pre-membrane (prM) and envelope (E) proteins (GAd-Zvp) or prM and the ectodomain of E protein (GAd-Eecto). Both vaccines induce humoral and cell-mediated immune responses and prevent lethality after ZIKV challenge in mice. Protection is antibody dependent, CD
Current Law Review Digest Series
Series by David S. Landis, John D. O\u27Neill, Arthur A. May, Arthur M. Diamond, Norbert S. Wleklinski, and Francis J. Paulson
Current Law Review Digest Series
Series by David S. Landis, John D. O\u27Neill, Arthur A. May, Arthur M. Diamond, Norbert S. Wleklinski, and Francis J. Paulson
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