Entry and productivity growth: evidence from microlevel panel data

How does entry affect productivity growth of incumbents? In this paper we exploit policy reforms in the United Kingdom that changed entry conditions by opening up the U.K. economy during the 1980s and panel data on British establishments to shed light on this question. We show that more entry, measured by a higher share of industry employment in foreign firms, has led to faster total factor productivity growth of domestic incumbent firms and thus to faster aggregate productivity growth

Can virtual seminars be used cost‐effectively to enhance student learning?

This paper describes a virtual seminar initiative designed to investigate the extent to which computer‐mediated communication (CMC) can cost‐effectively strengthen staff‐student interaction and enhance student group discussion, and thereby improve collaborative learning. After setting the scene by means of a brief review of the discursive potential of CMC, the establishment of an asynchronous bulletin board system on three modules in the Department of Sociology at the University of Manchester using industry standard software is described. Detailed time diaries kept by all staff involved revealed that organizing and running the virtual seminars were very much less time‐consuming than running face‐to‐face seminars. However, analysis of the students’ access to and mage of the virtual seminars indicates that some of them were disadvantaged by CMC and that they favoured face‐to‐face contact with lecturers over virtual seminars. The latter should therefore be part of a portfolio of teaching techniques rather than the sole form of collaborative learning. The conclusion is that a significant obstacle to benefiting from CMC is the further demand on staff time that results from adding virtual seminars as a supplement to existing teaching practices. Even though these extra demands may be modest, effectively deploying the discursive potential of CMC to enhance student learning increases staff effort rather than reducing it, as many have hoped or promised it would

<i>Spitzer</i> microlens measurement of a massive remnant in a well-separated binary

We report the detection and mass measurement of a binary lens OGLE-2015-BLG-1285La,b, with the more massive component having M1 > 1.35 M⊙ (80% probability). A main-sequence star in this mass range is ruled out by limits on blue light, meaning that a primary in this mass range must be a neutron star (NS) or black hole (BH). The system has a projected separation r⊥ = 6.1 ± 0.4 AU and lies in the Galactic bulge. These measurements are based on the "microlens parallax" effect, i.e., comparing the microlensing light curve as seen from Spitzer, which lay at 1.25 AU projected from Earth, to the light curves from four ground-based surveys, three in the optical and one in the near-infrared. Future adaptive optics imaging of the companion by 30 m class telescopes will yield a much more accurate measurement of the primary mass. This discovery both opens the path and defines the challenges to detecting and characterizing BHs and NSs in wide binaries, with either dark or luminous companions. In particular, we discuss lessons that can be applied to future Spitzer and Kepler K2 microlensing parallax observations

First LOFAR results on galaxy clusters

Deep radio observations of galaxy clusters have revealed the existence of diffuse radio sources related to the presence of relativistic electrons and weak magnetic fields in the intracluster volume. The role played by this non-thermal intracluster component on the thermodynamical evolution of galaxy clusters is debated, with important implications for cosmological and astrophysical studies of the largest gravitationally bound structures of the Universe. The low surface brightness and steep spectra of diffuse cluster radio sources make them more easily detectable at low-frequencies. LOFAR is the first instrument able to detect diffuse radio emission in hundreds of massive galaxy clusters up to their formation epoch. We present the first observations of clusters imaged by LOFAR and the huge perspectives opened by this instrument for non-thermal cluster studies.Comment: Proceedings of the 2012 week of the French Society of Astronomy and Astrophysics (SF2A) held in Nice, June 5th-8t

Controlling <i>In Planta</i> Gold Nanoparticle Synthesis and Size for Catalysis

Gold nanoparticles (Au-NPs) are used as catalysts for a diverse range of industrial applications. Currently, Au-NPs are synthesized chemically, but studies have shown that plants fed Au deposit, this element naturally as NPs within their tissues. The resulting plant material can be used to make biomass-derived catalysts. In vitro studies have shown that the addition of specific, short (∼10 amino acid) peptide/s to solutions can be used to control the NP size and shape, factors that can be used to optimize catalysts for different processes. Introducing these peptides into the model plant species, Arabidopsis thaliana (Arabidopsis), allows us to regulate the diameter of nanoparticles within the plant itself, consequently influencing the catalytic performance in the resulting pyrolyzed biomass. Furthermore, we show that overexpressing the copper and gold COPPER TRANSPORTER 2 (COPT2) in Arabidopsi sincreases the uptake of these metals. Adding value to the Au-rich biomass offers the potential to make plant-based remediation and stabilization of mine wastes financially feasible. Thus, this study represents a significant step toward engineering plants for the sustainable recovery of finite and valuable elements from our environment