Electron Microscope Studies of Surface Structure

Abstract Not Provided

Evaluating the pronunciation component of text-to-speech systems for English: A performance comparison of different approaches

The automatic derivation of word pronunciations from input text is a central task for any text-to-speech system. For general English text at least, this is often thought to be a solved problem, with manually-derived linguistic rules assumed capable of handling `novel' words missing from the system dictionary. Data-driven methods, based on machine learning of the regularities implicit in a large pronouncing dictionary, have received considerable attention recently but are generally thought to perform less well. However, these tentative beliefs are at best uncertain without powerful methods for comparing text-to-phoneme subsystems. This paper contributes to the development of such methods by comparing the performance of four representative approaches to automatic phonemisation on the same test dictionary. As well as rule-based approaches, three data-driven techniques are evaluated: pronunciation by analogy (PbA), NETspeak and IB1-IG (a modified k-nearest neighbour method). Issues involved in comparative evaluation are detailed and elucidated. The data-driven techniques outperform rules in accuracy of letter-to-phoneme translation by a very significant margin but require aligned text-phoneme training data and are slower. Best translation results are obtained with PbA at approximately 72% words correct on a reasonably large pronouncing dictionary, compared to something like 26% words correct for the rules, indicating that automatic pronunciation of text is not a solved problem

Geometry-dependent electrostatics near contact lines

Long-ranged electrostatic interactions in electrolytes modify their contact angles on charged substrates in a scale and geometry dependent manner. For angles measured at scales smaller than the typical Debye screening length, the wetting geometry near the contact line must be explicitly considered. Using variational and asymptotic methods, we derive new transcendental equations for the contact angle that depend on the electrostatic potential only at the three phase contact line. Analytic expressions are found in certain limits and compared with predictions for contact angles measured with lower resolution. An estimate for electrostatic contributions to {\it line} tension is also given.Comment: 3 .eps figures, 5p

Identifying the Neutrino mass Ordering with INO and NOvA

The relatively large value of $\theta_{13}$ established recently by the Daya Bay reactor experiment opens the possibility to determine the neutrino mass ordering with experiments currently under construction. We investigate synergies between the NOvA long-baseline accelerator experiment with atmospheric neutrino data from the India-based Neutrino Observatory (INO). We identify the requirements on energy and direction reconstruction and detector mass for INO necessary for a significant sensitivity. If neutrino energy and direction reconstruction at the level of 10% and 10 degree can be achieved by INO a determination of the neutrino mass ordering seems possible around 2020.Comment: 18 pages, 8 figures, minor improvements and clarifications, new panel in fig. 7, version to appear in JHEP, typo in eq. 4 correcte

Spectropolarimetry of the 3.4 micron absorption feature in NGC 1068

In order to test the silicate-core/organic-mantle model of galactic interstellar dust, we have performed spectropolarimetry of the 3.4 micron C-H bond stretch that is characteristic of aliphatic hydrocarbons, using the nucleus of the Seyfert 2 galaxy, NGC 1068, as a bright, dusty background source. Polarization calculations show that, if the grains in NGC 1068 had the properties assigned by the core-mantle model to dust in the galactic diffuse ISM, they would cause a detectable rise in polarization over the 3.4 micron feature. No such increase is observed. We discuss modifications to the basic core-mantle model, such as changes in grain size or the existence of additional non-hydrocarbon aligned grain populations, which could better fit the observational evidence. However, we emphasize that the absence of polarization over the 3.4 micron band in NGC 1068 - and, indeed, in every line of sight examined to date - can be readily explained by a population of small, unaligned carbonaceous grains with no physical connection to the silicates.Comment: ApJ, accepte

Search for Radiative Decays of Cosmic Background Neutrino using Cosmic Infrared Background Energy Spectrum

We propose to search for the neutrino radiative decay by fitting a photon energy spectrum of the cosmic infrared background to a sum of the photon energy spectrum from the neutrino radiative decay and a continuum. By comparing the present cosmic infrared background energy spectrum observed by AKARI and Spitzer to the photon energy spectrum expected from neutrino radiative decay with a maximum likelihood method, we obatined a lifetime lower limit of $3.1 \times 10^{12}$ to $3.8 \times 10^{12}$ years at 95% confidence level for the third generation neutrino $\nu_3$ in the $\nu_3$ mass range between 50 \mmev and 150 \mmev under the present constraints by the neutrino oscillation measurements. In the left-right symmetric model, the minimum lifetime of $\nu_3$ is predicted to be $1.5 \times 10^{17}$ years for $m_3$ of 50 \mmev. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of $1.5 \times 10^{17}$ years, by measuring a continuous energy spectrum of the cosmic infrared background

Hydrocarbon Dust Absorption in Seyfert Galaxies and ULIRGs

We present new spectroscopic observations of the 3.4 micron absorption feature in the Seyfert galaxies, NGC1068 and NGC7674, and the ultraluminous infrared galaxy, IRAS08572+3915. A signature of C-H bonds in aliphatic hydrocarbons, the 3.4 micron feature indicates the presence of organic material in Galactic and extragalactic dust. Here we compare the 3.4 micron feature in all the galaxies in which it has been detected. In several cases, the signal-to-noise ratio and spectral resolution permit a detailed examination of the feature profile, something which has rarely been attempted in extragalactic lines of sight. The 3.4 micron band in these galaxies closely resembles that seen in the Galactic diffuse ISM and in newly-formed dust in a protoplanetary nebula. The similarity implies a common carrier for the carbonaceous component of dust, and one which is resistant to processing in the interstellar and/or circumnuclear medium. We also examine the mid-IR spectrum of NGC1068, because absorption bands in the 5-8 micron region further constrain the chemistry of the 3.4 micron band carrier. While weak features like those present in the mid-IR spectrum of diffuse dust towards the Galactic center would be undetectable in NGC1068, the strong bands found in the spectra of many proposed dust analog materials are clearly absent, eliminating certain candidates and production mechanisms for the carrier. The absence of strong absorption features at 5-8 microns is also consistent with the interpretation that the similarity in the 3.4 micron feature in NGC1068 to that in Galactic lines of sight reflects real chemical similarity in the carbonaceous dust.Comment: 30 pages, 8 figures (preprint style), ApJ accepte

VLT/UVES Observations of Interstellar Molecules and Diffuse Bands in the Magellanic Clouds

We discuss the abundances of interstellar CH, CH+, and CN in the Magellanic Clouds (MC), derived from spectra of 7 SMC and 13 LMC stars obtained (mostly) with the VLT/UVES. CH and/or CH+ are detected toward 3 SMC and 9 LMC stars; CN is detected toward 2 stars. In the MC, the CH/H2 ratio is comparable to that found for diffuse Galactic molecular clouds in some sight lines, but is lower by factors up to 10-15 in others. The abundance of CH in the MC thus appears to depend on local physical conditions -- and not just on metallicity. The observed relationships between the column density of CH and those of CN, CH+, Na I, and K I in the MC are generally consistent with the trends observed in our Galaxy. Using existing data for the rotational populations of H2, we estimate temperatures, radiation field strengths, and local hydrogen densities for the diffuse molecular gas. Densities estimated from N(CH), assuming that CH is produced via steady-state gas-phase reactions, are considerably higher; much better agreement is found by assuming that the CH is made via the (still undetermined) process(es) responsible for the observed CH+. The UVES spectra also reveal absorption from the diffuse interstellar bands at 5780, 5797, and 6284 A in the MC. On average, the three DIBs are weaker by factors of 7-9 (LMC) and about 20 (SMC), compared to those observed in Galactic sight lines with similar N(H I), and by factors of order 2-6, relative to E(B-V), N(Na I), and N(K I). The detection of several of the ``C2 DIBs'', with strengths similar to those in comparable Galactic sight lines, however, indicates that no single, uniform scaling factor (e.g., one related to metallicity) applies to all DIBs (or all sight lines) in the MC. (abstract abridged)Comment: 59 pages, 15 figures, 10 tables; aastex; accepted to ApJ

Endothelial MAPKs Direct ICAM-1 Signaling to Divergent Inflammatory Functions.

Lymphocyte transendothelial migration (TEM) is critically dependent on intraendothelial signaling triggered by adhesion to ICAM-1. Here we show that endothelial MAPKs ERK, p38, and JNK mediate diapedesis-related and diapedesis-unrelated functions of ICAM-1 in cerebral and dermal microvascular endothelial cells (MVECs). All three MAPKs were activated by ICAM-1 engagement, either through lymphocyte adhesion or Ab-mediated clustering. MAPKs were involved in ICAM-1-dependent expression of TNF-α in cerebral and dermal MVECs, and CXCL8, CCL3, CCL4, VCAM-1, and cyclooxygenase 2 (COX-2) in cerebral MVECs. Endothelial JNK and to a much lesser degree p38 were the principal MAPKs involved in facilitating diapedesis of CD4(+) lymphocytes across both types of MVECs, whereas ERK was additionally required for TEM across dermal MVECs. JNK activity was critical for ICAM-1-induced F-actin rearrangements. Furthermore, activation of endothelial ICAM-1/JNK led to phosphorylation of paxillin, its association with VE-cadherin, and internalization of the latter. Importantly ICAM-1-induced phosphorylation of paxillin was required for lymphocyte TEM and converged functionally with VE-cadherin phosphorylation. Taken together we conclude that during lymphocyte TEM, ICAM-1 signaling diverges into pathways regulating lymphocyte diapedesis, and other pathways modulating gene expression thereby contributing to the long-term inflammatory response of the endothelium