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Along with a number of other computing technologies, cloud computing services are increasingly being promoted as a way of enabling openness, reproducibility, and the acceleration of scientific work. While there have been a variety of studies of the cloud in terms of computing performance, there has been little empirical attention to the changes going on around cloud computing at the level of work and practice. Through a qualitative, ethnographic study, we follow a cosmology research group’s transition from a shared high performance computing cluster to a cloud computing service, and examine the cloud service as a coordinative artifact being integrated into a larger ecology of existing practices and artifacts. We find that the transition involves both change and continuity in the group’s coordinative work and maintenance work, and point out some of the effects this adoption has on the group’s larger set of practices. Finally, we discuss practical implications this has for the broader adoption of cloud computing in university-based scientific work.

We test Milgromian dynamics (MOND) using wide binary stars (WBs) with separations of 2–30 kAU. Locally, the WB orbital velocity in MOND should exceed the Newtonian prediction by |$\approx 20~{{\ \rm per\ cent}}$| at asymptotically large separations given the Galactic external field effect (EFE). We investigate this with a detailed statistical analysis of Gaia DR3 data on 8611 WBs within 250 pc of the Sun. Orbits are integrated in a rigorously calculated gravitational field that directly includes the EFE. We also allow line-of-sight contamination and undetected close binary companions to the stars in each WB. We interpolate between the Newtonian and Milgromian predictions using the parameter αgrav, with 0 indicating Newtonian gravity and 1 indicating MOND. Directly comparing the best Newtonian and Milgromian models reveals that Newtonian dynamics is preferred at 19σ confidence. Using a complementary Markov Chain Monte Carlo analysis, we find that |$\alpha _{\rm {grav}} = -0.021^{+0.065}_{-0.045}$|⁠ , which is fully consistent with Newtonian gravity but excludes MOND at 16σ confidence. This is in line with the similar result of Pittordis and Sutherland using a somewhat different sample selection and less thoroughly explored population model. We show that although our best-fitting model does not fully reproduce the observations, an overwhelmingly strong preference for Newtonian gravity remains in a considerable range of variations to our analysis. Adapting the MOND interpolating function to explain this result would cause tension with rotation curve constraints. We discuss the broader implications of our results in light of other works, concluding that MOND must be substantially modified on small scales to account for local WBs. [ABSTRACT FROM AUTHOR]

Author(s): John A. Peacock (corresponding author) [1]; Shaun Cole [2]; Peder Norberg [2]; Carlton M. Baugh [2]; Joss Bland-Hawthorn [3]; Terry Bridges [3]; Russell D. Cannon [3]; Matthew Colless [4]; [...]

Along with a number of other computing technologies, cloud computing services are increasingly being promoted as a way of enabling openness, reproducibility, and the acceleration of scientific work. While there have been a variety of studies of the cloud in terms of computing performance, there has been little empirical attention to the changes going on around cloud computing at the level of work and practice. Through a qualitative, ethnographic study, we follow a cosmology research group’s transition from a shared high performance computing cluster to a cloud computing service, and examine the cloud service as a coordinative artifact being integrated into a larger ecology of existing practices and artifacts. We find that the transition involves both change and continuity in the group’s coordinative work and maintenance work, and point out some of the effects this adoption has on the group’s larger set of practices. Finally, we discuss practical implications this has for the broader adoption of cloud computing in university-based scientific work. [ABSTRACT FROM AUTHOR]

The enthusiasm around remote and independent working has rapidly gained momentum in the last few years. The digital nomad phenomenon has frequently been portrayed as an exemplar of this pattern and referred to by the media as a highly location‐independent form of nomadic work. However, findings from this study highlight the centrality of various spaces in digital nomadic work and suggest finding and configuring these spaces allows digital nomads to accomplish productive work. Building on interviews with 23 digital nomads and analyzing pictures of workspaces from Twitter, this study examines the unique relationship among disparate workspaces, work practices, and technologies that shape nomadic work. Our findings refine the common argument that nomadic workers can work from "anywhere, anytime," by attending to the large roles that space may play in shaping work. [ABSTRACT FROM AUTHOR]

Several recent studies have shown that very wide binary stars can potentially provide an interesting test for modified-gravity theories which attempt to emulate dark matter; these systems should be almost Newtonian according to standard dark-matter theories, while the predictions for MOND-like theories are distinctly different, if the various observational issues can be overcome. Here we explore an observational application of the test from the recent Gaia DR2 data release: we select a large sample of ∼24 000 candidate wide binary stars with distance |$\lt 200 \, {\rm pc}$| and magnitudes G < 16 from Gaia DR2, and estimated component masses using a main-sequence mass–luminosity relation. We then compare the frequency distribution of pairwise relative projected velocity (relative to circular-orbit value) as a function of projected separation; these distributions show a clear peak at a value close to Newtonian expectations, along with a long 'tail' which extends to much larger velocity ratios; the 'tail' is considerably more numerous than in control samples constructed from DR2 with randomized positions, so its origin is unclear. Comparing the velocity histograms with simulated data, we conclude that MOND-like theories without an external field effect (ExFE) are strongly inconsistent with the observed data since they predict a peak-shift in clear disagreement with the data; testing MOND-like theories with an ExFE is not decisive at present, but has good prospects to become decisive in future with improved modelling or understanding of the high-velocity tail, and additional spectroscopic data. [ABSTRACT FROM AUTHOR]

We examine the concept of personal knowledge management using data drawn from our study of digital nomads. We make two contributions: an empirical and conceptual development of knowledge management as it relates to independent workers and an advancement of social informatics that builds on Gibson's ecological perspective. Digital nomads provide an empirical basis to better understand how knowledge management is shifting from organization‐centric, with its concomitant emphasis on organizational information systems, to worker‐centric, which relies on personal knowledge ecologies. We advance this concept as a combination of personal knowledge management activities and the digital technologies that support them. Our data make clear that individuals are the locus of personal knowledge ecologies, but these ecologies are embedded in a larger community of collaborators, clients, and peers who are often extensively mediated by digital technologies. This embedding and mediation are at the core of the sociotechnical arrangements that define the personal knowledge ecologies that we document. [ABSTRACT FROM AUTHOR]

The standard Lambda cold dark matter model based on general relativity (GR) including cold dark matter (DM) is very successful at fitting cosmological observations, but recent non-detections of candidate dark matter particles mean that various modified-gravity theories remain of significant interest. The latter generally involve modifications to GR below a critical acceleration scale $${\sim } 10^{-10} \, {\rm m \, s^{-2}}$$. Wide-binary star systems with separations $${\gtrsim } 5 \, {\rm kau}$$ provide an interesting test for modified gravity, due to being in or near the low-acceleration regime and presumably containing negligible DM. Here, we explore the prospects for new observations pending from the GAIA spacecraft to provide tests of GR against modified Newtonian dynamics (MOND)- or tensor-vector-scalar (TeVeS)-like theories in a regime only partially explored to date. In particular, we find that a histogram of (3D) binary relative velocities, relative to equilibrium circular velocity predicted from the (2D) projected separation, predicts a rather sharp feature in this distribution for standard gravity, with an 80th (90th) percentile value close to 1.025 (1.14) with rather weak dependence on the eccentricity distribution. However, MOND/TeVeS theories produce a shifted distribution, with a significant increase in these upper percentiles. In MOND-like theories without an external field effect, there are large shifts of order unity. With the external field effect included, the shifts are considerably reduced to ∼0.04−0.08, but are still potentially detectable statistically given reasonably large samples and good control of contaminants. In principle, follow-up of GAIA -selected wide binaries with ground-based radial velocities accurate to $${\lesssim }\,0.03 {\rm \, km \, s^{-1} }$$ should be able to produce an interesting new constraint on modified-gravity theories. [ABSTRACT FROM AUTHOR]

It is well known that estimating cosmological parameters from cosmic microwave background (CMB) data alone results in a significant degeneracy between the total neutrino mass and several other cosmological parameters, especially the Hubble constant H0 and the matter density parameter Ωm. Adding low-redshift measurements such as baryon acoustic oscillations (BAOs) breaks this degeneracy and greatly improves the constraints on neutrino mass. The sensitivity is surprisingly high, for example, adding the ∼1 percent measurement of the BAO ratio rs/DV from the BOSS survey leads to a limit Σ mν < 0.19 eV, equivalent to Ων < 0.0045 at 95 per cent confidence. For the case of Σ mν < 0.6 eV, the CMB degeneracy with neutrino mass almost follows a track of constant sound horizon angle (Howlett et al. 2012). For a ΛCDM + mν model, we use simple but quite accurate analytic approximations to derive the slope of this track, giving dimensionless multipliers between the neutrino to matter ratio (xν ≡ ων/ωcb) and the shifts in other cosmological parameters. The resulting multipliers are substantially larger than 1: conserving the CMB sound horizon angle requires parameter shifts δln H0 ≈ −2 δxν, δln Ωm ≈ +5 δxν, δln ωΛ ≈ −6.2 δxν, and most notably δωΛ ≈ −14 δων. These multipliers give an intuitive derivation of the degeneracy direction, which agrees well with the numerical likelihood results from the Planck team. [ABSTRACT FROM AUTHOR]

The Visible and Infrared Survey Telescope for Astronomy (VISTA) is the 4-m wide-field survey telescope at ESO's Paranal Observatory, equipped with the world's largest near-infrared imaging camera (VISTA IR Camera, VIRCAM), with 1.65 degree diameter field of view, and 67 Mpixels giving 0.6 deg2 active pixel area, operating at wavelengths 0:8-2:3 μm. We provide a short history of the project, and an overview of the technical details of the full system including the optical design, mirrors, telescope structure, IR camera, active optics, enclosure and software. The system includes several innovative design features such as the f/1 primary mirror, the dichroic cold-baffle camera design and the sophisticated wavefront sensing system delivering closed-loop 5-axis alignment of the secondary mirror. We conclude with a summary of the delivered performance, and a short overview of the six ESO public surveys in progress on VISTA. [ABSTRACT FROM AUTHOR]

Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift zacc ~ 0.7. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known 'turnover' in the SN distance residuals µ relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, not the deceleration predicted by cold dark matter and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model (w = -1/3), and also remapping the z-axis to u = ln(1 + z); we outline a number of useful and intuitive properties of this presentation. We conclude that there are significant complementarities between SNe and baryon acoustic oscillations (BAOs): SNe offer high precision at low redshifts and give good constraints on the net amount of acceleration since z ~ 0.7, but are weak at constraining zacc; while radial BAO measurements are probably superior for placing direct constraints on zacc. [ABSTRACT FROM AUTHOR]

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We present the development and applications of dielectric elastomers. For the last 10 years the significance of this class of polymers has risen as more applications seem possible and first products have been commercialized. [ABSTRACT FROM AUTHOR]

ABSTRACT The baryon acoustic oscillation (BAO) feature in the distribution of galaxies provides a fundamental standard ruler which is widely used to constrain cosmological parameters. In most analyses, the comoving length of the ruler is inferred from a combination of cosmic microwave background (CMB) observations and theory. However, this inferred length may be biased by various non-standard effects in early universe physics; this can lead to biased inferences of cosmological parameters such as H0, Ωm and w, so it would be valuable to measure the absolute BAO length by combining a galaxy redshift survey and a suitable direct low- z distance measurement. One obstacle is that low-redshift BAO surveys mainly constrain the ratio rS/ D V( z), where D V is a dilation scale which is not directly observable by standard candles. Here, we find a new approximation [ABSTRACT FROM AUTHOR]

ABSTRACT We propose a new and highly model-independent test of cosmic acceleration by comparing observations of the baryon acoustic oscillation (BAO) scale at low and intermediate redshifts: we derive a new inequality relating BAO observables at two distinct redshifts, which must be satisfied for any reasonable homogeneous non-accelerating model, but is violated by models similar to Λ cold dark matter, due to acceleration in the recent past. This test is fully independent of the theory of gravity (general relativity or otherwise), the Friedmann equations, cosmic microwave background and supernova observations: the test assumes only the cosmological principle, and that the length-scale of the BAO feature is fixed in comoving coordinates. Given realistic medium-term observations from the Baryon Oscillation Spectroscopic Survey, this test is expected to exclude all homogeneous non-accelerating models at ∼4σ significance, and can reach with next-generation surveys. [ABSTRACT FROM AUTHOR]

We constrain fiat cosmological models with a joint likelihood analysis of a new compilation of data from the cosmic microwave background (CMB) and from the 2dF Galaxy Redshift Survey (2dFGRS). Fitting the CMB alone yields a known degeneracy between the Hubble constant h and the matter density Ωm, which arises mainly from preserving the location of the peaks in the angular power spectrum. This 'horizon-angle degeneracy' is considered in some detail and is shown to follow the simple relation &Omega[sub m] h[sup 3.4] = constant. Adding the 2dF-GRS power spectrum constrains Ω[sub m] h and breaks the degeneracy. If tensor anisotropies are assumed to be negligible, we obtain values for the Hubble constant of h = 0.665 ± 0.047, the matter density Ω[sub m] = 0.313 ± 0.055, and the physical cold dark matter and baryon densities Ω[sub c] h² = 0.115 ± 0.009, Ω[sub b] h² = 0.022 ± 0.002 (standard rms errors). Including a possible tensor component causes very little change to these figures; we set an upper limit to the tensorto-scalar ratio of r < 0.7 at a 95 per cent confidence level. We then show how these data can be used to constrain the equation of state of the vacuum, and find w < -0.52 at 95 per cent confidence. The preferred cosmological model is thus very well specified, and we discuss the precision with which future CMB data can be predicted, given the model assumptions. The 2dFGRS power-spectrum data and covariance matrix, and the CMB data compilation used here, are available from http://www.roe.ac.uk/∼wjp/. [ABSTRACT FROM AUTHOR]

The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250 000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2° diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than . The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning around the SGP, and the other in the northern Galactic hemisphere spanning along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000 deg[sup 2] and has a median depth of . Adaptive tiling is used to give a highly uniform sampling rate of 93 per cent over the whole survey region. Redshifts are measured from spectra covering at a two-pixel resolution of 9.0 Å and a median S/N of 13 pixel[sup -1]. All redshift identifications are visually checked and assigned a quality parameter Q in the range redshifts are 98.4 per cent reliable and have an rms uncertainty of 85 km s[sup -1]. The overall redshift completeness for redshifts is 91.8 per cent, but this varies with magnitude from 99 per cent for the brightest galaxies to 90 per cent for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www.mso.anu.edu.au/2dFGRS. [ABSTRACT FROM AUTHOR]

We present the development and applications of dielectric elastomers. For the last 10 years the significance of this class of polymers has risen as more applications seem possible and first products have been commercialized., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)