392 research outputs found

    The orbit of 2010 TK7. Possible regions of stability for other Earth Trojan asteroids

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    Recently the first Earth Trojan has been observed (Mainzer et al., ApJ 731) and found to be on an interesting orbit close to the Lagrange point L4 (Connors et al., Nature 475). In the present study we therefore perform a detailed investigation on the stability of its orbit and moreover extend the study to give an idea of the probability to find additional Earth-Trojans. Our results are derived using different approaches: a) we derive an analytical mapping in the spatial elliptic restricted three-body problem to find the phase space structure of the dynamical problem. We explore the stability of the asteroid in the context of the phase space geometry, including the indirect influence of the additional planets of our Solar system. b) We use precise numerical methods to integrate the orbit forward and backward in time in different dynamical models. Based on a set of 400 clone orbits we derive the probability of capture and escape of the Earth Trojan asteroids 2010 TK7. c) To this end we perform an extensive numerical investigation of the stability region of the Earth's Lagrangian points. We present a detailed parameter study in the regime of possible stable tadpole and horseshoe orbits of additional Earth-Trojans, i.e. with respect to the semi-major axes and inclinations of thousands of fictitious Trojans. All three approaches underline that the Earth Trojan asteroid 2010 TK7 finds himself in an unstable region on the edge of a stable zone; additional Earth-Trojan asteroids may be found in this regime of stability.Comment: 11 pages, 16 figure

    Ultracool dwarf benchmarks with \emph{Gaia} primaries

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    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We explore the potential of \emph{Gaia} for the field of benchmark ultracool/brown dwarf companions, and present the results of an initial search for metal-rich/metal-poor systems. A simulated population of resolved ultracool dwarf companions to \emph{Gaia} primary stars is generated and assessed. Of order \sim24,000 companions should be identifiable outside of the Galactic plane (b>10|b| > 10\,deg) with large-scale ground- and space-based surveys including late M, L, T, and Y types. Our simulated companion parameter space covers 0.02M/M0.10.02 \le M/M_{\odot} \le 0.1, 0.1age/Gyr140.1 \le {\rm age/Gyr} \le 14, and 2.5[Fe/H]0.5-2.5 \le {\rm [Fe/H]} \le 0.5, with systems required to have a false alarm probability 0.6\, kau}\,Peer reviewedFinal Accepted Versio

    Organizational and Supervisory Apology Effectiveness: Apology Giving in Work Settings

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    We synthesize the interdisciplinary literature into a heuristic for crafting effective organizational and supervisory apologies (the OOPS four-component apology). In the first experiment, we demonstrate how an offense committed by an organization is perceived to be more egregious than an offense committed by a friend or supervisor. Furthermore, results did not support that OOPS apologies are unequally effective if issued by a friend, supervisor, or organization. In the second experiment, we test OOPS apology-training effectiveness. Results indicated that trained participants crafted more effective apologies. Our apology heuristic is an innovation for training business communicators how to apologize effectively.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    The influence of the physical education teacher on intrinsic motivation, self-confidence, anxiety, and pre-and post-competition mood states

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    One of the fundamental problems facing teachers of physical education (PE) is how to increase pupils' motivation. From the point of view of goal achievement, guidelines need to be established so that information may be used to greater effect in classes. This study examined the relationship between the motivational climate created by the PE teacher and the intrinsic motivation of the preparatory sessions together with self-confidence and anxiety prior to competition and pre- and post-competition mood states. The sample was made up of school children (M age = 11.7) from a state school (N = 115), who, after an introduction to an athletics course of 12 sessions, took part in a sports competition. During this time, a teacher (trained to this effect) manipulated the motivational climate, adapting the strategies of TARGET (11, 12, 26, 28). The mastery climate was linked to enjoyment, perceived ability, and effort in the PE classes, as well as to pre-competition somatic anxiety and post-competition vigor. On the other hand, the performance climate was associated with self-confidence, pre-competition vigor, and post-competition stress. The results are discussed in relation to achievement goal theory and motivational climate manipulation

    Assessing psychological health : the contribution of psychological strengths

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    Balanced assessment of mental health involves assessing wellbeing and strengths as well as psychopathology. The character strengths of curiosity, gratitude, hope, optimism and forgiveness, are assessed in 214 new undergraduates and their relationships to mental health, subjective wellbeing and self-esteem explored. Scoring the mental health scale for psychiatric caseness, case and non-case students did not differ in character strengths, positive affect or life satisfaction, supporting a dual-factor model. Hope pathways and gratitude predicted mental health. Gratitude, hope agency and exploratory curiosity predicted positive affect. Gratitude and hope agency predicted life satisfaction. Hope agency, hope pathways, exploratory curiosity and gratitude predicted self-esteem, with absorption curiosity a negative predictor. The benefits of assessing strengths are discussed and interventions designed to develop them. Keywords: character strengths; mental health; subjective wellbeing; dual-factor mental health model; self-estee

    Dynamic relationships between phonological memory and reading: a five year longitudinal study from age 4 to 9

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    We reconcile competing theories of the role of phonological memory in reading development, by uncovering their dynamic relationship during the first five years of school. Phonological memory, reading and phoneme awareness were assessed in 780 phonics-educated children at age 4, 5, 6 and 9. Confirmatory factor analyses demonstrated that phonological memory loaded onto two factors: verbal short-term memory (verbal STM; phonological tasks that loaded primarily on serial order memory), and nonword repetition. Using longitudinal structural equation models, we found that verbal STM directly predicted early word-level reading from age 4 to 6, reflecting the importance of serial-order memory for letter-by-letter decoding. In contrast, reading had no reciprocal influence on the development of verbal STM. The relationship between nonword repetition and reading was bidirectional across the five years of study: nonword repetition and reading predicted each other both directly and indirectly (via phoneme awareness). Indirect effects from nonword repetition (and verbal STM) to reading support the view that phonological memory stimulates phonemically-detailed representations through repeated encoding of complex verbal stimuli. Similarly, the indirect influence of reading on nonword repetition suggests that improved reading ability promotes the phoneme-level specificity of phonological representations. Finally, the direct influence from reading to nonword repetition suggests that better readers use orthographic cues to help them remember and repeat new words accurately

    Measuring Orthodontic Treatment Satisfaction: Questionnaire Development and Preliminary Validation

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    The aims of this study were to develop a reliable self-report measure of consumer satisfaction with orthodontic treatment, and to preliminarily assess its validity

    Solar System Objects Observed in the SDSS Commissioning Data

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    We discuss measurements of the properties of about 10,000 asteroids detected in 500 deg2 of sky in the Sloan Digital Sky Survey (SDSS) commissioning data. The moving objects are detected in the magnitude range 14 < r < 21.5, with a baseline of 5 minutes. Extensive tests show that the sample is at least 98% complete, with the contamination rate of less than 3%. We find that the size distribution of asteroids resembles a broken power-law, independent of the heliocentric distance: D^{-2.3} for 0.4 km < D < 5 km, and D^{-4} for 5 km < D < 40 km. As a consequence of this break, the number of asteroids with r < 21.5 is ten times smaller than predicted by extrapolating the power-law relation observed for brighter asteroids (r < 18). The observed counts imply that there are about 530,000 objects with D>1 km in the asteroid belt, or about four times less than previous estimates. The distribution of main belt asteroids in the 4-dimensional SDSS color space is bimodal, and the two groups can be associated with S (rocky) and C (carbonaceous) asteroids. A strong bimodality is also seen in the heliocentric distribution of asteroids and suggests the existence of two distinct belts: the inner rocky belt, about 1 AU wide (FWHM) and centered at R~2.8 AU, and the outer carbonaceous belt, about 0.5 AU wide and centered at R~3.2 AU. The colors of Hungarias, Mars crossers, and near-Earth objects are more similar to the C-type than to S-type asteroids, suggesting that they originate in the outer belt. (abridged).Comment: 89 pages, 31 figures, submitted to A
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