7,586 research outputs found
Eco-innovation practices’ adoption in the automotive industry
Eco-innovation is a construct that is gaining increasing interest from academics and researchers since it is commonly considered in the literature as one of the strategies that allow manufacturing companies not only to significantly reduce the negative impacts on the environment but also the generation of pollutants. However, little is known about the adoption of eco-innovation practices in manufacturing companies, particularly in the automotive industry. Therefore, this research has as main objective to fill this gap in the literature and explore the interdependence between eco-innovation of products, processes and management. The study is conducted through a research framework consisting of 3 measurement scales, 14 items and 3 hypotheses and an extensive review of the literature. A self-administered questionnaire was distributed to a sample of 460 companies in the automotive and auto parts industry in Mexico. Data were analyzed through Confirmatory Factor Analysis, Descriptive Statistics and Structural Equation Modelling. The results obtained show that product eco-innovation, process eco-innovation and management eco-innovation are good indicators for the adoption of eco-innovation practices for companies in the automotive and auto parts industry. The paper addresses a research gap in the academic literature in the eco-innovation field by providing evidence on the interdependence between eco-innovation of products, processes and management and the implementation of their practices in the automotive industry.N/
Connecting substellar and stellar formation. The role of the host star's metallicity
Most of our current understanding of the planet formation mechanism is based
on the planet metallicity correlation derived mostly from solar-type stars
harbouring gas-giant planets. To achieve a far more reaching grasp on the
substellar formation process we aim to analyse in terms of their metallicity a
diverse sample of stars (in terms of mass and spectral type) covering the whole
range of possible outcomes of the planet formation process (from planetesimals
to brown dwarfs and low-mass binaries). Our methodology is based on the use of
high-precision stellar parameters derived by our own group in previous works
from high-resolution spectra by using the iron ionisation and equilibrium
conditions. All values are derived in an homogeneous way, except for the M
dwarfs where a methodology based on the use of pseudo equivalent widths of
spectral features was used. Our results show that as the mass of the substellar
companion increases the metallicity of the host star tendency is to lower
values. The same trend is maintained when analysing stars with low-mass stellar
companions and a tendency towards a wide range of host star's metallicity is
found for systems with low mass planets. We also confirm that more massive
planets tend to orbit around more massive stars. The core-accretion formation
mechanism for planet formation achieves its maximum efficiency for planets with
masses in the range 0.2 and 2 M. Substellar objects with higher
masses have higher probabilities of being formed as stars. Low-mass planets and
planetesimals might be formed by core-accretion even around low-metallicity
stars.Comment: Accepted by A&
Tunnel spectroscopy in ac-driven quantum dot nanoresonators
Electronic transport in a triple quantum dot shuttle device in the presence
of an ac field is analyzed within a fully quantum mechanical framework. A
generalized density matrix formalism is used to describe the time evolution for
electronic state occupations in a dissipative phonon bath. In the presence of
an ac gate voltage, the electronic states are dressed by photons and the
interplay between photon and vibrational sidebands produces current
characteristics that obey selection rules. Varying the ac parameters allows to
tune the tunneling current features. In particular, we show that coherent
destruction of tunneling can be achieved in our device
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The timing of the formation and usage of replicase clusters in S-phase nuclei of human diploid fibroblasts
The sites of nascent DNA synthesis were compared
with the distribution of the proliferating cell nuclear antigen (PCNA) in S-phase nuclei of human diploid fibroblasts (HDF) by two in vitro techniques. Firstly, proliferating fibroblasts growing in culture that had been synchronised at S-phase were microinjected with the thymidine analogue biotin-11-dUTP. The sites of incorporation of biotin into injected cells
were compared with the distribution of PCNA by
indirect immunofluorescence microscopy and laser
scanning confocal microscopy (LSCM). In common
with other studies, a progression of patterns for both biotin incorporation and PCNA localisation was observed. However, we did not always observe
coincidence in these patterns, the pattern of biotin incorporation often resembling the expected, preceding distribution of PCNA. In nuclei in which the pattern of biotin incorporation appeared to be identical to the distribution of PCNA, LSCM revealed that not all of the sites of PCNA immunofluorescence were incorporating biotin at the same time. Secondly,
nuclei which had been isolated from quiescent
cultures of HDF were innoculated into cell-free
extracts of Xenopus eggs which support DNA replication in vitro. Following innoculation into these extracts DNA replication was initiated in each nucleus. The sites of DNA synthesis were detected by biotin-11-dUTP incorporation and compared with the distribution of PCNA by indirect immunofluorescence. Only a single pattern of biotin incorporation and PCNA distribution was observed. PCNA accumulated
at multiple discrete spots some 15min before any biotin incorporation was observed. When biotin incorporation did occur, LSCM revealed almost complete coincidence between the sites of DNA synthesis and the sites at which PCNA was localised.Brunel Open Access Publishing Fun
The bias-extension test for the analysis of in-plane shear properties of textile composite reinforcements and prepregs: a review
The bias-extension test is a rather simple experiment aiming to determine in-plane shear properties of textile composite reinforcements. However the mechanics during the test involves fibrous material at large shear strains and large rotations of the fibres. Several aspects are still being studied and are not yet modeled in a consensual manner. The standard analysis of the test is based on two assumptions: inextensibility of the fibers and rotations at the yarn crossovers without slippage. They lead to the development of zones with constant fibre orientations proper to the bias-extension test. Beyond the analysis of the test within these basic assumptions, the paper presents studies that have been carried out on the lack of verification of these hypothesis (slippage, tension in the yarns, effects of fibre bending). The effects of temperature, mesoscopic modeling and tension locking are also considered in the case of the bias-extension test
Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. V.: A Massive Jupiter orbiting the very low metallicity giant star BD+03 2562 and a possible planet around HD~103485
We present two evolved stars from the TAPAS (Tracking Advanced PlAnetary
Systems) with HARPS-N project devoted to RV precision measurements of
identified candidates within the PennState - Torun Centre for Astronomy Planet
Search. Evolved stars with planets are crucial to understand the dependency of
the planet formation mechanism on the mass and metallicity of the parent star
and to study star-planet interactions. The paper is based on precise radial
velocity (RV) measurements, for HD 103485 we collected 57 epochs over 3317 days
with the Hobby-Eberly Telescope and its High Resolution Spectrograph and 18
ultra-precise HARPS-N data over 919 days. For BD+03 2562 we collected 46 epochs
of HET data over 3380 days and 19 epochs of HARPS-N data over 919 days. We
present the analysis of the data and the search for correlations between the RV
signal and stellar activity, stellar rotation and photometric variability.
Based on the available data, we interpret the RV variations measured in both
stars as Keplerian motion. Both stars have masses close to Solar (1.11 and
1.14), very low metallicities ([Fe/H]=-0.50 and -0.71), and, both have Jupiter
planetary mass companions (m sin i=7 and 6.4 Mj), in close to terrestrial
orbits (1.4 and 1.3~au), with moderate eccentricities (e=0.34 and 0.2).
However, we cannot totally exclude that the signal in the case of HD~103485 is
due to rotational modulation of active regions. Based on the current data, we
conclude that BD+03 2562 has a bona fide planetary companion while for HD
103485 we cannot totally exclude that the best explanation for the RV signal
modulations is not the existence of a planet but stellar activity. If, the
interpretation remains that both stars have planetary companions they represent
systems orbiting very evolved stars with very low metallicities, a challenge to
the conditions required for the formation of massive giant gas planets.Comment: Acepted A&A 12 pages, 11 figure
Tunneling spectroscopy of the superconducting state of URu2Si2
We present measurements of the superconducting gap of URuSi made with
scanning tunneling microscopy (STM) using a superconducting tip of Al. We find
tunneling conductance curves with a finite value at the Fermi level. The
density of states is V shaped at low energies, and the quasiparticle peaks are
located at values close to the expected superconducting gap from weak coupling
BCS theory. Our results point to rather opened gap structures and gap nodes on
the Fermi surface
Development of thermodynamically consistent machine-learning equations of state: Application to the Mie fluid
A procedure for deriving thermodynamically consistent data-driven equations of state (EoS) for fluids is presented. The method is based on fitting the Helmholtz free energy using artificial neural networks to obtain a closed-form relationship between the thermophysical properties of fluids (FE-ANN EoS). As a proof-of-concept, an FE-ANN EoS is developed for the Mie fluids, starting from a database obtained by classical molecular dynamics simulations. The FE-ANN EoS is trained using first- (pressure and internal energy) and second-order (e.g., heat capacities, Joule–Thomson coefficients) derivative data. Additional constraints ensure that the data-driven model fulfills thermodynamically consistent limits and behavior. The results for the FE-ANN EoS are shown to be as accurate as the best available analytical model while being developed in a fraction of the time. The robustness of the “digital” equation of state is exemplified by computing physical behavior it has not been trained on, for example, fluid phase equilibria. Furthermore, the model’s internal consistency is successfully assessed using Brown’s characteristic curves
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