•Sharing economy platforms have a set of essential affordances for mediating exchanges.•Sharing economy platforms can be discussed and compared in terms of centralization.•The literature is ...preoccupied with centralized, profit-driven platforms like Uber.•Future research must develop a conceptualization of decentralized sharing contexts.•Future research must engage directly with the nature of sharing economy technologies.
Over the last few years the sharing economy has been changing the way that people share and conduct transactions in digital spaces. This research phenomenon has drawn scholars from a large number of disparate fields and disciplines into an emerging research area. Given the variety of perspectives represented, there is a great need to collect and connect what has been done, and to identify some common themes, which will serve as a basis for future discussions on the crucial roles played by digital platforms in the sharing economy. Drawing on a collection of 435 publications on the sharing economy and related terms, we identify some trends in the literature and underlying research interests. Specifically, we organize the literature around the concept of platform mediation, and draw a set of essential affordances of sharing economy technologies from the reviewed literature. We present the notion of platform centralization/decentralization as an effective organizing principle for the variety of perspectives on the sharing economy, and also evaluate scholars' treatment of technology itself. Finally, we identify important gaps in the existing literature on the relationship between digital platforms and sharing economy, and provide directions for future investigations.
ABSTRACT We present ALMA detections of the C ii 158 m emission line and the underlying far-infrared (FIR) continuum of three quasars at 6.6 < z < 6.9 selected from the VIKING survey. The C ii line ...fluxes range between 1.6 and 3.4 Jy km s−1 (C ii luminosities ∼(1.9-3.9) × 109 L ). We measure continuum flux densities of 0.56-3.29 mJy around 158 m (rest frame), with implied FIR luminosities of (0.6-7.5) × 1012 L and dust masses Md = (0.7-24) × 108 M . In one quasar we derive a dust temperature of K from the continuum slope, below the canonical value of 47 K. Assuming that the C ii and continuum emission are powered by star formation, we find star formation rates from 100 to 1600 M yr−1 based on local scaling relations. The LC ii/LFIR ratios in the quasar hosts span a wide range from (0.3-4.6) × 10−3, including one quasar with a ratio that is consistent with local star-forming galaxies. We find that the strength of the LC ii and 158 m continuum emission in z 6 quasar hosts correlates with the quasar's bolometric luminosity. In one quasar, the C ii line is significantly redshifted by ∼1700 km s−1 with respect to the Mg ii broad emission line. Comparing to values in the literature, we find that, on average, the Mg ii is blueshifted by 480 km s−1 (with a standard deviation of 630 km s−1) with respect to the host galaxy redshift, i.e., one of our quasars is an extreme outlier. Through modeling we can rule out a flat rotation curve for our brightest C ii emitter. Finally, we find that the ratio of black hole mass to host galaxy (dynamical) mass is higher by a factor of 3-4 (with significant scatter) than local relations.
We present ALMA band 3 observations of the CO(6-5), CO(7-6), and C i 369 m emission lines in three of the highest-redshift quasar host galaxies at . These measurements constitute the highest-redshift ...CO detections to date. The target quasars have previously been detected in C ii 158 m emission and the underlying FIR dust continuum. We detect (spatially unresolved, at a resolution of >2″, or 14 kpc) CO emission in all three quasar hosts. In two sources, we detect the continuum emission around 400 m (rest-frame), and in one source we detect C i at low significance. We derive molecular gas reservoirs of (1-3) × 1010 in the quasar hosts, i.e., approximately only 10 times the mass of their central supermassive black holes. The extrapolated C ii-to-CO(1-0) luminosity ratio is 2500-4200, consistent with measurements in galaxies at lower redshift. The detection of the C i line in one quasar host galaxy and the limit on the C i emission in the other two hosts enables a first characterization of the physical properties of the interstellar medium in z ∼ 7 quasar hosts. In the sources, the derived global CO/C ii/C i line ratios are consistent with expectations from photodissociation regions, but not X-ray-dominated regions. This suggest that quantities derived from the molecular gas and dust emission are related to ongoing star-formation activity in the quasar hosts, providing further evidence that the quasar hosts studied here harbor intense starbursts in addition to their active nucleus.
Algorithmic management in a work context Jarrahi, Mohammad Hossein; Newlands, Gemma; Lee, Min Kyung ...
Big data & society,
07/2021, Letnik:
8, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The rapid development of machine-learning algorithms, which underpin contemporary artificial intelligence systems, has created new opportunities for the automation of work processes and management ...functions. While algorithmic management has been observed primarily within the platform-mediated gig economy, its transformative reach and consequences are also spreading to more standard work settings. Exploring algorithmic management as a sociotechnical concept, which reflects both technological infrastructures and organizational choices, we discuss how algorithmic management may influence existing power and social structures within organizations. We identify three key issues. First, we explore how algorithmic management shapes pre-existing power dynamics between workers and managers. Second, we discuss how algorithmic management demands new roles and competencies while also fostering oppositional attitudes toward algorithms. Third, we explain how algorithmic management impacts knowledge and information exchange within an organization, unpacking the concept of opacity on both a technical and organizational level. We conclude by situating this piece in broader discussions on the future of work, accountability, and identifying future research steps.
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.
A stretch of the imagination: Electroactive polymers and especially dielectric elastomers have become more significant over the last 10 years as more applications seem possible and first products have been commercialized. The general principles of dielectric elastomers and recent developments in the field are described. The most promising developments are based on polyurethane and silicone systems. The picture shows one of the first commercial actuators based on electroactive polymers.
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, thedichroic 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
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.
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
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.
![BRIGHT [C ii] AND DUST EMIS...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "BRIGHT [C ii] AND DUST EMISSION IN THREE z > 6.6 QUASAR HOST GALAXIES OBSERVED BY ALMA")
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