Horizontal mergers for buyer power

Salant et al. (1983) showed in a Cournot setting that horizontal mergers are unprofitable because outsiders react by increasing their output. We show that this negative effect may be compensated by the positive effect that horizontal mergers have on the buyer power of merging firms in input markets.

Low fermentation pH is a trigger to alcohol production, but a killer to chain elongation

Gasification of organic wastes coupled to syngas fermentation allows the recovery of carbon in the form of commodity chemicals, such as carboxylates and biofuels. Acetogenic bacteria ferment syngas to mainly two-carbon compounds, although a few strains can also synthesize four-, and six-carbon molecules. In general, longer carbon chain products have a higher biotechnological (and commercial) value due to their higher energy content and their lower water solubility. However, de-novo synthesis of medium-chain products from syngas is quite uncommon in acetogenic bacteria. An alternative to de-novo synthesis is bioproduction of short-chain products (C2 and C4), and their subsequent elongation to C4, C6, or C8 through reversed beta-oxidation metabolism. This two-step synergistic approach has been successfully applied for the production of up to C8 compounds, although the accumulation of alcohols in these mixed cultures remained below detection limits. The present work investigates the production of higher alcohols from syngas by open mixed cultures (OMC). A syngas-fermenting community was enriched from sludge of an anaerobic digester for a period of 109 days in a lab-scale reactor. At the end of this period, stable production of ethanol and butanol was obtained. C6 compounds were only transiently produced at the beginning of the enrichment phase, during which Clostridium kluyveri, a bacterium able to carry out carbon chain elongation, was detected in the community. Further experiments showed pH as a critical parameter to maintain chain elongation activity in the co-culture. Production of C6 compounds was recovered by preventing fermentation pH to decrease below pH 4.5-5. Finally, experiments showed maximal production of C6 compounds (0.8 g/L) and alcohols (1.7 g/L of ethanol, 1.1 g/L of butanol, and 0.6 g/L of hexanol) at pH 4.8. In conclusion, low fermentation pH is critical for the production of alcohols, although detrimental to C. kluyveri. Fine control of fermentation pH to final values around 4.8 could allow sustained production of higher alcohols

On the Implementation of a Multiple Output Algorithm for Defeasible Argumentation

In a previous work we defined a recursive warrant semantics for Defeasible Logic Programming based on a general notion of collective conflict among arguments. The main feature of this recursive semantics is that an output of a program is a pair consisting of a set of warranted and a set of blocked formulas. A program may have multiple outputs in case of circular definitions of conflicts among arguments. In this paper we design an algorithm for computing each output and we provide an experimental evaluation of the algorithm based on two SAT encodings defined for the two main combinatorial subproblems that arise when computing warranted and blocked conclusions for each output.The authors acknowledge the Spanish projects ARINF (TIN2009-14704-C03-01), TASSAT (TIN2010-20967-C04-03) and EdeTRI (TIN2012-39348-C02-01).Peer Reviewe

No surviving companion in Kepler's supernova

We have surveyed Kepler's supernova remnant in search of the companion star of the explosion. We have gone as deep as 2.6 solar luminosities in the stars within 20% of the radius of the remnant. We use FLAMES at the VLT-UT2 telescope to obtain high resolution spectra of the stellar candidates selected from HST images. The resulting set of stellar parameters suggests that these stars come from a rather ordinary mixture of field stars (mostly giants). A few of the stars seem to have low [Fe/H] (< -1) and they are consistent with being metal-poor giants. The radial velocities and rotational velocities vrot sin i are very well determined. There are no fast rotating stars as vrot sin i < 20 km/s. The radial velocities from the spectra and the proper motions determined from HST images are compatible with those expected from the Besan\c{c}on model of the Galaxy. The strong limits placed on luminosity suggest that this supernova could have arisen either from the core-degenerate scenario or from the double-degenerate scenario.Comment: ApJ accepted, 7 figures and 7 table

Effects of dimethyl sulfoxide in cholesterol-containing lipid membranes: A comparative study of experiments in silico and with cells

Dimethyl sulfoxide (DMSO) has been known to enhance cell membrane permeability of drugs or DNA. Molecular dynamics (MD) simulations with single-component lipid bilayers predicted the existence of three regimes of action of DMSO: membrane loosening, pore formation and bilayer collapse. We show here that these modes of action are also reproduced in the presence of cholesterol in the bilayer, and we provide a description at the atomic detail of the DMSO-mediated process of pore formation in cholesterol-containing lipid membranes. We also successfully explore the applicability of DMSO to promote plasma membrane permeability to water, calcium ions (Ca2+) and Yo-Pro-1 iodide (Yo-Pro-1) in living cell membranes. The experimental results on cells in culture can be easily explained according to the three expected regimes: in the presence of low doses of DMSO, the membrane of the cells exhibits undulations but no permeability increase can be detected, while at intermediate DMSO concentrations cells are permeabilized to water and calcium but not to larger molecules as Yo-Pro-1. These two behaviors can be associated to the MD-predicted consequences of the effects of the DMSO at low and intermediate DMSO concentrations. At larger DMSO concentrations, permeabilization is larger, as even Yo-Pro-1 can enter the cells as predicted by the DMSO-induced membrane-destructuring effects described in the MD simulations.Fil: de Ménorval, Marie-Amélie. Centre National de la Recherche Scientifique; FranciaFil: Mir, Lluis M.. Centre National de la Recherche Scientifique; FranciaFil: Fernández, María Laura. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Computación. Laboratorio de Sistemas Complejos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Reigada, Ramon. Universidad de Barcelona; Españ

Effects of dimethyl sulfoxide in cholesterol-containing lipid membranes: a comparative study of experiments in silico and with cells

Dimethyl sulfoxide (DMSO) has been known to enhance cell membrane permeability of drugs or DNA. Molecular dynamics (MD) simulations with single-component lipid bilayers predicted the existence of three regimes of action of DMSO: membrane loosening, pore formation and bilayer collapse. We show here that these modes of action are also reproduced in the presence of cholesterol in the bilayer, and we provide a description at the atomic detail of the DMSO-mediated process of pore formation in cholesterol-containing lipid membranes. We also successfully explore the applicability of DMSO to promote plasma membrane permeability to water, calcium ions (Ca2+) and Yo-Pro-1 iodide (Yo-Pro-1) in living cell membranes. The experimental results on cells in culture can be easily explained according to the three expected regimes: in the presence of low doses of DMSO, the membrane of the cells exhibits undulations but no permeability increase can be detected, while at intermediate DMSO concentrations cells are permeabilized to water and calcium but not to larger molecules as Yo-Pro-1. These two behaviors can be associated to the MD-predicted consequences of the effects of the DMSO at low and intermediate DMSO concentrations. At larger DMSO concentrations, permeabilization is larger, as even Yo-Pro-1 can enter the cells as predicted by the DMSO-induced membrane-destructuring effects described in the MD simulations

A possible surviving companion of the SN Ia in the Galactic SNR G272.2-3.2

We use the {\it Gaia} EDR3 to explore the Galactic supernova remnant SNR G272.2-3.2, produced by the explosion of a Type Ia supernova (SNIa), about 7,500 years ago, to search for a surviving companion. From the abundances in the SNR ejecta, G272.2-3.2 is a normal SN Ia. The {\it Gaia} parallaxes allow to select the stars located within the estimated distance range of the SNR, and the {\it Gaia} proper motions to study their kinematics. From the {\it Gaia} EDR3 photometry, we construct the HR diagram of the selected sample, which we compare with the theoretical predictions for the evolution of possible star companions of SNIa. We can discard several proposed types of companions by combining kinematics and photometry. We can also discard hypervelocity stars. We focus our study on the kinematically most peculiar star, {\it Gaia} EDR3 5323900215411075328 (hereafter MV-G272), a 8.9 $\sigma$ outlier in proper motion. It is of M1-M2 stellar type. Its trajectory on the sky locates it at the center of the SNR, 6,000--8,000 years ago, a unique characteristic among the the sample. Spectra allow a stellar parameters determination and a chemical abundance analysis. In conclusion, we have a candidate to be the surviving companion of the SN Ia that resulted in SNR G272.2-3.2. It is supported by its kinematical characteristics and its trajectory within the SNR. This opens the possibility of a single-degenerate scenario for a SN Ia with an M-type dwarf companion.Comment: 35 pages, 19 Figures, 5 Tables, published as ApJ 947, 90

Nanopaper-Based Organic Inkjet-Printed Diodes

AbstractThe rise of internet of things (IoTs) applications has led to the development of a new generation of light‐weight, flexible, and cost‐effective electronics. These devices and sensors have to be simultaneously easily replaceable and disposable while being environmentally sustainable. Thus, the introduction of new functionalized materials with mechanical flexibility that can be processed using large‐area and facile fabrication methods (as, for example, printing technologies) has become a matter of great interest in the scientific community. In this context, cellulose nanofibers (CNFs) are renewable, affordable, robust, and nontoxic materials that are rapidly emerging as components for eco‐friendly electronics. Their combination with conductive polymers (CPs) to obtain conductive nanopapers (CNPs) allows moving their functionality from just substrates to active components of the device. In this work, a route for the inkjet‐printing of organic diodes is outlined. The proposed strategy is based on the use of CNPs as both substrates and bottom electrodes onto which insulator and organic semiconducting layers are deposited to fabricate novel diode structures. Remarkable rectification ratios of up to 1.2 × 103 at |3 V| and a current density up to 5.1 µA cm−2 are achieved. As a proof‐of‐concept of the potentiality of the approach for versatile, low‐temperature, and disposable sensing applications, an NO2 gas sensor is presented