High resolution imaging with Fresnel interferometric arrays: suitability for exoplanet detection

We propose a new kind of interferometric array that yields images of high dynamic range and large field. The numerous individual apertures in this array form a pattern related to a Fresnel zone plate. This array can be used for astrophysical imaging over a broad spectral bandwidth spanning from the U.V. (50 nanometers) to the I.R. (20 microns). Due to the long focal lengths involved, this instrument requires formation-flying of two space borne vessels. We present the concept and study the S/N ratio in different situations, then apply these results to probe the suitability of this concept to detect exoplanets.Comment: 12 pages, 19 figures, to be published in A&

Identifying risk for atypical parenting behavior using prenatal profiles of interpersonal trauma experiences and PTSD symptoms

Experiences of interpersonal trauma and symptoms of PTSD greatly impact the ability to form and maintain meaningful relationships, which is especially problematic during the perinatal period due to the formation of the mother-child relationship. Interpersonal trauma and symptoms of PTSD present considerable risk for the emergence of a concerning class of “atypical” maternal behaviors (e.g., contradictory communication, sexualized/role reversed behavior, and severe withdrawal) that have serious implications for child social-emotional development. However, past research has focused primarily on how maternal experiences of childhood maltreatment and, to a lesser extent, PTSD symptom severity, predict atypical parenting behaviors. The present study aimed to better understand the association between both child- and adulthood experiences of interpersonal trauma and PTSD symptoms, and atypical parenting behaviors. One hundred twenty women from a longitudinal study that spanned from the third trimester of pregnancy through 3-years postpartum were utilized. Experiences of childhood maltreatment and intimate partner violence (IPV) were assessed during pregnancy. Atypical parenting behaviors were coded from mother-infant interactions 1-year postpartum. Bivariate associations between experiences of interpersonal trauma, prenatal PTSD symptoms, and atypical parenting behavior were few in number. Profiles of interpersonal trauma experiences and prenatal PTSD symptoms were identified using latent profile analysis. Subsequent analyses indicated that experiencing multiple types of childhood maltreatment and prenatal IPV predicted later atypical parenting behavior. Reported PTSD symptoms across clusters, as well as having less education and younger age, presented risk for atypical parenting behavior. Results increase understanding about individual differences in prenatal risk for the development of atypical parenting behavior and have implications for interventions aimed at preventing or reducing parenting problems

Zenithal bistability in a nematic liquid crystal device with a monostable surface condition

The ground-state director configurations in a grating-aligned, zenithally bistable nematic device are calculated in two dimensions using a Q tensor approach. The director profiles generated are well described by a one-dimensional variation of the director across the width of the device, with the distorted region near the grating replaced by an effective surface anchoring energy. This work shows that device bistability can in fact be achieved by using a monostable surface term in the one-dimensional model. This implies that is should be possible to construct a device showing zenithal bistability without the need for a micropatterned surface

Space-time estimation of a particle system model

13 pagesLet X be a discrete time contact process (CP) on the discrete bidimensional lattice as define by Durett - Levin (1994) . We study estimation of the model based on space-time evolution on a finite subset of sites. For this, we make use of a marginal pseudo-likelihood. The estimator obtained is consistent and asymptoticaly normal for non-vanishing supercritical CP. Numerical studies confirm these results

A Methodology for the Diagnostic of Aircraft Engine Based on Indicators Aggregation

Aircraft engine manufacturers collect large amount of engine related data during flights. These data are used to detect anomalies in the engines in order to help companies optimize their maintenance costs. This article introduces and studies a generic methodology that allows one to build automatic early signs of anomaly detection in a way that is understandable by human operators who make the final maintenance decision. The main idea of the method is to generate a very large number of binary indicators based on parametric anomaly scores designed by experts, complemented by simple aggregations of those scores. The best indicators are selected via a classical forward scheme, leading to a much reduced number of indicators that are tuned to a data set. We illustrate the interest of the method on simulated data which contain realistic early signs of anomalies.Comment: Proceedings of the 14th Industrial Conference, ICDM 2014, St. Petersburg : Russian Federation (2014

Self-assembly of peptide-based nanostructures: Synthesis and biological activity

Peptide-based nanostructures have received much attention in the field of drug targeting. In fact, peptides have many advantages such as simplicity of the structure, biocompatibility, and chemical diversity. Moreover, some peptides, which are called cell-penetrating peptides, can cross cellular membranes and carry small molecules, small interfering RNA, or viruses inside live cells. These molecules are often covalently or noncovalently linked to cargoes, thus forming amphiphilic conjugates that can self-assemble. Supramolecular nanostructures formed from peptides are used in nanomedicine as a carrier to protect a drug and to target cancer cells. This review explores aliphatic-chain–conjugated peptides and drug-conjugated peptides that can self-assemble. Special emphasis is placed on the synthesis procedure, nanostructure formation, and biological activity

Laser Guide Star for Large Segmented-Aperture Space Telescopes, Part I: Implications for Terrestrial Exoplanet Detection and Observatory Stability

Precision wavefront control on future segmented-aperture space telescopes presents significant challenges, particularly in the context of high-contrast exoplanet direct imaging. We present a new wavefront control architecture that translates the ground-based artificial guide star concept to space with a laser source aboard a second spacecraft, formation flying within the telescope field-of-view. We describe the motivating problem of mirror segment motion and develop wavefront sensing requirements as a function of guide star magnitude and segment motion power spectrum. Several sample cases with different values for transmitter power, pointing jitter, and wavelength are presented to illustrate the advantages and challenges of having a non-stellar-magnitude noise limited wavefront sensor for space telescopes. These notional designs allow increased control authority, potentially relaxing spacecraft stability requirements by two orders of magnitude, and increasing terrestrial exoplanet discovery space by allowing high-contrast observations of stars of arbitrary brightness.Comment: Submitted to A

Comparison of Two Roadside Survey Procedures for Dwarf Mistletoes on the Sawtooth National Forest, Idaho

Two roadside surveys were conducted for dwarf mistletoes parasitizing lodgepole pine and Douglas-fir on the Sawtooth National Forest, Idaho. One survey used variable-radius plots located less than 150 m from roads. The 2nd survey used variable-radius plots established at 200-m intervals along 1600-m transects run perpendicular to the same roads. Estimates of the incidence (percentage of trees infected and percentage of plots infested) and severity (average dwarf mistletoe rating) for both lodgepole pine and Douglas-fir dwarf mistletoes were not significantly different for the 2 survey methods. These findings are further evidence that roadside-plot surveys and transect-plot surveys conducted away from roads provide similar estimates of the incidence of dwarf mistletoes for large forested areas