University of Portsmouth

About: University of Portsmouth is a education organization based out in Portsmouth, Portsmouth, United Kingdom. It is known for research contribution in the topics: Population & Galaxy. The organization has 5452 authors who have published 14256 publications receiving 424346 citations. The organization is also known as: Portsmouth and Gosport School of Science and Art & Portsmouth and Gosport School of Science and the Arts.

Cosmology in generalized Proca theories

Abstract: We consider a massive vector field with derivative interactions that propagates only the 3 desired polarizations (besides two tensor polarizations from gravity) with second-order equations of motion in curved space-time. The cosmological implications of such generalized Proca theories are investigated for both the background and the linear perturbation by taking into account the Lagrangian up to quintic order. In the presence of a matter fluid with a temporal component of the vector field, we derive the background equations of motion and show the existence of de Sitter solutions relevant to the late-time cosmic acceleration. We also obtain conditions for the absence of ghosts and Laplacian instabilities of tensor, vector, and scalar perturbations in the small-scale limit. Our results are applied to concrete examples of the general functions in the theory, which encompass vector Galileons as a specific case. In such examples, we show that the de Sitter fixed point is always a stable attractor and study viable parameter spaces in which the no-ghost and stability conditions are satisfied during the cosmic expansion history.

The completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: BAO and RSD measurements from anisotropic clustering analysis of the quasar sample in configuration space between redshift 0.8 and 2.2

Abstract: We measure the anisotropic clustering of the quasar sample from Data Release 16 (DR16) of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (eBOSS). A sample of $343,708$ spectroscopically confirmed quasars between redshift $0.8

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

Abstract: Citation: Chuang, C. H., Prada, F., Pellejero-Ibanez, M., Beutler, F., Cuesta, A. J., Eisenstein, D. J., . . . Thomas, D. (2016). The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Single-probe measurements from CMASS anisotropic galaxy clustering. Monthly Notices of the Royal Astronomical Society, 461(4), 3781-3793. doi:10.1093/mnras/stw1535

Towards an Affect Space for robots to display emotional body language

Abstract: In order for robots to be socially accepted and generate empathy it is necessary that they display rich emotions. For robots such as Nao, body language is the best medium available given their inability to convey facial expressions. Displaying emotional body language that can be interpreted whilst interacting with the robot should significantly improve its sociability. This research investigates the creation of an Affect Space for the generation of emotional body language to be displayed by robots. To create an Affect Space for body language, one has to establish the contribution of the different positions of the joints to the emotional expression. The experiment reported in this paper investigated the effect of varying a robot's head position on the interpretation, Valence, Arousal and Stance of emotional key poses. It was found that participants were better than chance level in interpreting the key poses. This finding confirms that body language is an appropriate medium for robot to express emotions. Moreover, the results of this study support the conclusion that Head Position is an important body posture variable. Head Position up increased correct identification for some emotion displays (pride, happiness, and excitement), whereas Head Position down increased correct identification for other displays (anger, sadness). Fear, however, was identified well regardless of Head Position. Head up was always evaluated as more highly Aroused than Head straight or down. Evaluations of Valence (degree of negativity to positivity) and Stance (degree to which the robot was aversive to approaching), however, depended on both Head Position and the emotion displayed. The effects of varying this single body posture variable were complex.

Chemical and structural characterization of exopolymers produced by Pseudomonas sp. NCIMB 2021 in continuous culture.

Abstract: The growth of marine Pseudomonas sp. NCIMB 2021 as continuous cultures in the presence of surfaces of AISI 316 stainless steel allowed the isolation and partial chemical characterization of exopolymers released into the culture medium (free exopolymers), as well as capsular and biofilm exopolymers. Fourier-transform infrared (FTIR) spectroscopy demonstrated the presence of O- and N-acetylation within the carbohydrate moieties and a predominant 310-helical structure of the protein component, highly resistant to hydrogen/deuterium exchange. Differences between the exopolymers were apparent. Relatively less uronic acid residues were detected in the capsular exopolymers compared to either the biofilm or free exopolymers. O- and N-acetylation were greatest in the biofilm exopolymer. SDS-PAGE protein profiles confirmed differences between exopolymers. The secondary structures of proteins determined using FTIR spectroscopy indicated that the capsular exopolymer had reduced helical content and an increased aggregated strand content compared to the biofilm exopolymer. However, the free exopolymer had an increased β-sheet component and a reduced unordered component when compared to the biofilm and capsular exopolymers. These data suggest that exopolymer chemistry varies with cellular mode of growth.