161 research outputs found

    Voids in Modified Gravity Reloaded: Eulerian Void Assignment

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    We revisit the excursion set approach to calculate void abundances in chameleon-type modified gravity theories, which was previously studied by Clampitt, Cai & Li. We focus on properly accounting for the void-in-cloud effect, i.e. the growth of those voids sitting in overdense regions may be restricted by the evolution of their surroundings. This effect may change the distribution function of voids hence affect predictions on the differences between modified gravity (MG) and general relativity (GR). We show that the thin-shell approximation usually used to calculate the fifth force is qualitatively good but quantitatively inaccurate. Therefore, it is necessary to numerically solve the fifth force in both overdense and underdense regions. We then generalize the Eulerian-void-assignment method of Paranjape, Lam & Sheth to our modified gravity model. We implement this method in our Monte Carlo simulations and compare its results with the original Lagrangian methods. We find that the abundances of small voids are significantly reduced in both MG and GR due to the restriction of environments. However, the change in void abundances for the range of void radii of interest for both models is similar. Therefore, the difference between models remains similar to the results from the Lagrangian method, especially if correlated steps of the random walks are used. As Clampitt et al., we find that the void abundance is much more sensitive to MG than halo abundances. Our method can then be a faster alternative to N-body simulations for studying the qualitative behaviour of a broad class of theories. We also discuss the limitations and other practical issues associated with its applications

    Pairwise Well-Formed Modes and Transformations

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    One of the most significant attitudinal shifts in the history of music occurred in the Renaissance, when an emerging triadic consciousness moved musicians towards a new scalar formation that placed major thirds on a par with perfect fifths. In this paper we revisit the confrontation between the two idealized scalar and modal conceptions, that of the ancient and medieval world and that of the early modern world, associated especially with Zarlino. We do this at an abstract level, in the language of algebraic combinatorics on words. In scale theory the juxtaposition is between well-formed and pairwise well-formed scales and modes, expressed in terms of Christoffel words or standard words and their conjugates, and the special Sturmian morphisms that generate them. Pairwise well-formed scales are encoded by words over a three-letter alphabet, and in our generalization we introduce special positive automorphisms of F3F3, the free group over three letters.Comment: 12 pages, 3 figures, paper presented at the MCM2017 at UNAM in Mexico City on June 27, 2017, keywords: pairwise well-formed scales and modes, well-formed scales and modes, well-formed words, Christoffel words, standard words, central words, algebraic combinatorics on words, special Sturmian morphism

    The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster

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    We study how chemical abundances of late B-, A- and early F-type stars evolve with time, and we search for correlations between the abundance of chemical elements and other stellar parameters, such as effective temperature and Vsini. We have observed a large number of B-, A- and F-type stars belonging to open clusters of different ages. In this paper we concentrate on the Praesepe cluster (log t = 8.85), for which we have obtained high resolution, high signal-to-noise ratio spectra of sixteen normal A- and F-type stars and one Am star, using the SOPHIE spectrograph of the Observatoire de Haute-Provence. For all the observed stars, we have derived fundamental parameters and chemical abundances. In addition, we discuss another eight Am stars belonging to the same cluster, for which the abundance analysis had been presented in a previous paper. We find a strong correlation between peculiarity of Am stars and Vsini. The abundance of the elements underabundant in Am stars increases with Vsini, while it decreases for the overabundant elements. Chemical abundances of various elements appear correlated with the iron abundance.Comment: Accepted for publication on A&

    The detection of the imprint of filaments on cosmic microwave background lensing

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    Galaxy redshift surveys, such as 2dF, SDSS, 6df, GAMA and VIPERS, have shown that the spatial distribution of matter forms a rich web, known as the cosmic web. The majority of galaxy survey analyses measure the amplitude of galaxy clustering as a function of scale, ignoring information beyond a small number of summary statistics. Since the matter density field becomes highly non-Gaussian as structure evolves under gravity, we expect other statistical descriptions of the field to provide us with additional information. One way to study the non-Gaussianity is to study filaments, which evolve non-linearly from the initial density fluctuations produced in the primordial Universe. In our study, we report the first detection of CMB (Cosmic Microwave Background) lensing by filaments and we apply a null test to confirm our detection. Furthermore, we propose a phenomenological model to interpret the detected signal and we measure how filaments trace the matter distribution on large scales through filament bias, which we measure to be around 1.5. Our study provides a new scope to understand the environmental dependence of galaxy formation. In the future, the joint analysis of lensing and Sunyaev-Zel'dovich observations might reveal the properties of `missing baryons', the vast majority of the gas which resides in the intergalactic medium and has so far evaded most observations

    Explaining the Praesepe blue straggler HD 73666

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    The blue straggler phenomenon is not yet well explained by current theory; however, evolutionary models of star clusters call for a good knowledge of it. Here we try to understand the possible formation scenario of HD 73666, a blue straggler member of the Praesepe cluster. We compile the known physical properties of HD 73666 found in the literature, focusing in particular on possible binarity and the abundance pattern. HD 73666 appears to be slowly rotating, has no detectable magnetic field, and has normal abundances, thereby excluding close binary evolution and mass transfer processes. There is no evidence of a hot radiation source. With the use of theoretical results on blue straggler formation present in literature, we are able to conclude that HD 73666 was probably formed by physical collision involving at least one binary system, between 5 and 350 Myr (50 Myr if the star is an intrinsic slow rotator) ago.Comment: Accepted for publication on Astronomy and Astrophysic

    Virtual Team Leader Communication:Employee Perception and Organizational Reality

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    Based on a study of leader communication effectiveness conducted in a large human resource outsourcing firm, this article reports how virtual team members’ perceptions of their leaders’ effective use of communication tools and techniques affect team performance outcomes. The study also investigates the role that trust plays in moderating the relationship between virtual team members’ perceptions of their leaders’ effective use of communication and team performance. Analysis of 458 responses from 68 teams found a positive relationship between virtual team members’ perceptions of leaders’ effective use of communications and team members’ perception of their team’s performance. The study also found that trust strengthens the relationship between perceived leader communication effectiveness and team performance results. Last, the study also revealed serious organizational alignment issues between what team members perceived to be effective leader communication, their perception of team performance outcomes, and the organizations performance measured by a balanced scorecard

    The Iowa Homemaker vol.26, no.2

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    Alma Mater, J. C. Harris, page 2 Travel With Poise, Mary Ann Hakes, page 3 Report From Athens, Joan Kelleher, page 4 Blanche Pederson Interviews an Aussie Bride, Blanche Pederson, page 5 Coeds are Veterans, Too, Mary Margaret Ryan, page 6 Future Home Economics Classroom, Helen Hochriem, page 7 Vicky Grins at the Sun, Breta Soldat, page 9 What’s New in Home Economics, Marjorie Clampitt, page 10 Wardrobe Worries? Here’s What We Wear, Textiles and Clothing Club, page 12 “I Have a Dozen Bosses”, Genevieve Callahan, page 14 Albino Rats Get in on the Ground Floor, Margaret Waterland, page 17 Alums Prove Chemistry can Pay, June Welch, page 18 Education Begins Egyptian Modernizing, Lois Bronson, page 19 Across Alumnae Desks, Mary Neff, page 21 Keeping Up With Today, Joyce Edgar, page 22 How Does Your Garden Grow?, Irene Meyer, page 23 Alums in the News, Goldie Rouse, page 2

    Self-similarity and universality of void density profiles in simulation and SDSS data

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    The stacked density profile of cosmic voids in the galaxy distribution provides an important tool for the use of voids for precision cosmology. We study the density profiles of voids identified using the ZOBOV watershed transform algorithm in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. We compare different methods for reconstructing density profiles scaled by the void radius and show that the most commonly used method based on counts in shells and simple averaging is statistically flawed as it underestimates the density in void interiors. We provide two alternative methods that do not suffer from this effect; one based on Voronoi tessellations is also easily able to account from artefacts due to finite survey boundaries and so is more suitable when comparing simulation data to observation. Using this method, we show that the most robust voids in simulation are exactly self-similar, meaning that their average rescaled profile does not depend on the void size. Within the range of our simulation, we also find no redshift dependence of the mean profile. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The mean profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids

    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
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