Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra

We present a technique to extract radial velocity measurements from echelle spectrograph observations of rapidly rotating stars ($V\sin{i} \gtrsim 50$ km s$^{-1}$). This type of measurement is difficult because the line widths of such stars are often comparable to the width of a single echelle order. To compensate for the scarcity of lines and Doppler information content, we have developed a process that forward-models the observations, fitting the radial velocity shift of the star for all echelle orders simultaneously with the echelle blaze function. We use our technique to extract radial velocity measurements from a sample of rapidly rotating A- and B-type stars used as calibrator stars observed by the California Planet Survey observations. We measure absolute radial velocities with a precision ranging from 0.5-2.0 km s$^{-1}$ per epoch for more than 100 A- and B-type stars. In our sample of 10 well-sampled stars with radial velocity scatter in excess of their measurement uncertainties, three of these are single-lined binaries with long observational baselines. From this subsample, we present detections of two previously unknown spectroscopic binaries and one known astrometric system. Our technique will be useful in measuring or placing upper limits on the masses of sub-stellar companions discovered by wide-field transit surveys, and conducting future spectroscopic binarity surveys and Galactic space-motion studies of massive and/or young, rapidly-rotating stars.Comment: Accepted to ApJ

Visual Hebb repetition effects survive changes to both output order and concurrent articulation

Building upon the work of Guerrette et al. (2017), we examine the effect of output order on the visual Hebb repetition effect. We limit the opportunities for forward recall at test by using a novel positional recall procedure, employing non-verbal visual stimuli, and requiring participants to undertake concurrent articulation (CA). During the encoding phase, participants received sequences of six unfamiliar-faces. For every third sequence, participants received the same faces in the same serial order (i.e. the Hebb sequence). For the remaining trials, the sequence items were presented in a random order (i.e. the filler sequences). At test, participants were required to either select the faces in their order of original presentation (SR) or recall the serial position of each individually re-presented face tested in a randomised order (PR). For both recall conditions, the Hebb repetition effect was evident, and this persisted with CA. The findings demonstrate that the Hebb repetition effect is not dependent upon forward recall and is consistent with the view that the effect is underpinned by perceptual processing rather than repeated retrieval

Measurement of the Nodal Precession of WASP-33 b via Doppler Tomography

We have analyzed new and archival time series spectra taken six years apart during transits of the hot Jupiter WASP-33 b, and spectroscopically resolved the line profile perturbation caused by the Rossiter-McLaughlin effect. The motion of this line profile perturbation is determined by the path of the planet across the stellar disk, which we show to have changed between the two epochs due to nodal precession of the planetary orbit. We measured rates of change of the impact parameter and the sky-projected spin-orbit misalignment of $db/dt=-0.0228_{-0.0018}^{+0.0050}$ yr$^{-1}$ and $d\lambda/dt=-0.487_{-0.076}^{+0.089}$~$^{\circ}$ yr$^{-1}$, respectively, corresponding to a rate of nodal precession of $d\Omega/dt=0.373_{-0.083}^{+0.031}$~$^{\circ}$ yr$^{-1}$. This is only the second measurement of nodal precession for a confirmed exoplanet transiting a single star. Finally, we used the rate of precession to set limits on the stellar gravitational quadrupole moment of $9.4\times10^{-5}<J_2<6.1\times10^{-4}$.Comment: Published in ApJL. 5 pages, 3 figures. Corrected error in the calculation of J_

Statistical Models of Reconstructed Phase Spaces for Signal Classification

This paper introduces a novel approach to the analysis and classification of time series signals using statistical models of reconstructed phase spaces. With sufficient dimension, such reconstructed phase spaces are, with probability one, guaranteed to be topologically equivalent to the state dynamics of the generating system, and, therefore, may contain information that is absent in analysis and classification methods rooted in linear assumptions. Parametric and nonparametric distributions are introduced as statistical representations over the multidimensional reconstructed phase space, with classification accomplished through methods such as Bayes maximum likelihood and artificial neural networks (ANNs). The technique is demonstrated on heart arrhythmia classification and speech recognition. This new approach is shown to be a viable and effective alternative to traditional signal classification approaches, particularly for signals with strong nonlinear characteristics

Chewing gum modifies state-anxiety and alertness under conditions of social stress

Objectives: The finding that chewing gum can moderate state-anxiety under conditions of acute stress¹ has proved difficult to replicate.2,4 The present study examines the extent to which chewing gum can moderate state-anxiety under conditions of acute social stress. Method: In a between-participants design, 36 participants completed a task comprising a mock job interview (a variation on the Trier Social Stress Task3, which included a mental arithmetic component) whilst either chewing gum or without gum. Self-rated measures of mood and anxiety were taken at baseline, after a 10-minute presentation preparation stage, after the 10-minute presentation, and following a 5-minute recovery stage. Results: Post-presentation measures reflected increased state-anxiety and decrease self-rated calmness and contentedness. Chewing gum attenuated the rise in state-anxiety whilst increasing self-rated alertness. Chewing gum did not affect contentedness or calmness. Conclusions: The findings indicate that chewing gum can act to reduce anxiety under conditions of acute social stress: a finding consistent with Scholey et al.1 Furthermore, the data add to the growing body of literature demonstrating that chewing gum can increase alertness.1,2,4,

The Impact of Residence Design on Freshman Outcomes: Dormitories Versus Suite-Style Residences

This study was designed to measure affective, behavioural, and cognitive variables in a sample of 3159 first-year students, and to compare these variables by the type of residence building in which the student lived. Students living in suite-style buildings reported a greater sense of belonging, and higher activity levels than students living in dormitory- style buildings. Furthermore, sense of belonging was predicted by high extraversion and low conscientiousness. This suggests that introverted, conscientious students living in traditional dormitory-style buildings may be most at-risk of feeling “out-of-place” in residence.Cette étude a été crée pour évaluer les variables émotionnelles, comportementales, et cognitives dans une panel de 3159 étudiants dans leur première année d’université, et pour comparer ces variables par le type d’édifi ce de résidence dans laquelle les étudiantes vivaient. Etudiants vivant dans les immeubles de style suite ont rapporte un sens d’appartenance plus grand, et des niveaux plus élevées d’activité que celles qui vivait dans les immeubles de style foyer. En plus, un sens d’appartenance a été prédit par haute extraversion et des niveaux bas de conscience. Cela suggère que les étudiants introverties et consciencieux qui vivent dans les immeubles traditionnelles de style foyer seront peut-être les plus exposer à sentir « hors-de-place ». &nbsp