2,962 research outputs found
Family ownership and control as drivers for environmental, social, and governance in family firms
Sluggish market demand can deteriorate the financial situation of a company and affect a shareholder's decision to adopt environmental, social, and governance criteria (ESG). According to the socioemotional wealth theory, family firms place significant emphasis on sustainable development and long-term orientation, but this emphasis can be either internally or externally driven according to the type of involvement chosen by the owning family. Therefore, this study uses listed family firms to explore the relationship between different types of family involvement (i.e., family ownership and control, the influence of market competition, and the institutionalisation level of the environment in which a firm decides to pursue ESG criteria). We performed a multivariate regression analysis on a sample of 1,151 Chinese companies to test these relationships and found that both family ownership and control are positively related to ESG scores. Market competition negatively moderates the influence of both family ownership and control on the adoption of ESG criteria. Moreover, the influence of family control is negatively moderated by the institutional environment. Thus, types of family involvement seem to be relevant for the firm's engagement with ESG criteria
Multi-wavelength and black hole mass properties of Low Luminosity Active Nuclei
We investigate the relation between the X-ray nuclear emission, optical
emission line, radio luminosity and black hole mass for a sample of nearby
Seyfert galaxies. Strong linear correlations between the 2-10 keV and [OIII],
radio luminosities have been found, showing the same slopes found in quasars
and luminous Seyfert galaxies, thus implying independence from the level of
nuclear activity displayed by the sources. Moreover, despite the wide range of
Eddington ratios (L/L(Edd)) tested here (six orders of magnitude, from 0.1 down
to 10^(-7), no correlation is found between the X-ray, optical emission lines,
radio luminosities and the black hole mass. These results suggest that low
luminosity Seyfert galaxies are a scaled down version of luminous AGN and
probably are powered by the same physical processes.Comment: 6 pages, 3 figures, contributed talk presented at the Workshop "The
multicoloured landscape of compact objects and their explosive origin",
Cefalu' (Sicily), 11-24 June 2006, to be published by AI
Probing the spin states of three interacting electrons in quantum dots
We observe a low-lying sharp spin mode of three interacting electrons in an
array of nanofabricated AlGaAs/GaAs quantum dots by means of resonant inelastic
light scattering. The finding is enabled by a suppression of the inhomogeneous
contribution to the excitation spectra obtained by reducing the number of
optically-probed quantum dots. Supported by configuration-interaction
calculations we argue that the observed spin mode offers a direct probe of
Stoner ferromagnetism in the simplest case of three interacting spin one-half
fermions
Dust emission at 8-mic and 24-mic as Diagnostics of HII Region Radiative Transfer
We use the Spitzer SAGE survey of the Magellanic Clouds to evaluate the
relationship between the 8-mic PAH emission, 24-mic hot dust emission, and HII
region radiative transfer. We confirm that in the higher-metallicity Large
Magellanic Cloud, PAH destruction is sensitive to optically thin conditions in
the nebular Lyman continuum: objects identified as optically thin candidates
based on nebular ionization structure show 6 times lower median 8-mic surface
brightness (0.18 mJy arcsec^-2) than their optically thick counterparts (1.2
mJy arcsec^-2). The 24-mic surface brightness also shows a factor of 3 offset
between the two classes of objects (0.13 vs 0.44 mJy arcsec^-2, respectively),
which is driven by the association between the very small dust grains and
higher density gas found at higher nebular optical depths. In contrast, PAH and
dust formation in the low-metallicity Small Magellanic Cloud is strongly
inhibited such that we find no variation in either 8-mic or 24-mic emission
between our optically thick and thin samples. This is attributable to extremely
low PAH and dust production together with high, corrosive UV photon fluxes in
this low-metallicity environment. The dust mass surface densities and
gas-to-dust ratios determined from dust maps using Herschel HERITAGE survey
data support this interpretation.Comment: Accepted to ApJ, May 15, 2017. 10 pages, 9 figure
Feedback from massive stars at low metallicities : MUSE observations of N44 and N180 in the Large Magellanic Cloud
Accepted for publication in MNRAS, 27 pages, 21 figuresWe present MUSE integral field data of two HII region complexes in the Large Magellanic Cloud (LMC), N44 and N180. Both regions consist of a main superbubble and a number of smaller, more compact HII regions that formed on the edge of the superbubble. For a total of 11 HII regions, we systematically analyse the radiative and mechanical feedback from the massive O-type stars on the surrounding gas. We exploit the integral field property of the data and the coverage of the HeII5412 line to identify and classify the feedback-driving massive stars, and from the estimated spectral types and luminosity classes we determine the stellar radiative output in terms of the ionising photon flux . We characterise the HII regions in terms of their sizes, morphologies, ionisation structure, luminosity and kinematics, and derive oxygen abundances via emission line ratios. We analyse the role of different stellar feedback mechanisms for each region by measuring the direct radiation pressure, the pressure of the ionised gas, and the pressure of the shock-heated winds. We find that stellar winds and ionised gas are the main drivers of HII region expansion in our sample, while the direct radiation pressure is up to three orders of magnitude lower than the other terms. We relate the total pressure to the star formation rate per unit area, , for each region and find that stellar feedback has a negative effect on star formation, and sets an upper limit to as a function of increasing pressure.Peer reviewe
G\"odel-type universes in f(T) gravity
The issue of causality in gravity is investigated by examining the
possibility of existence of the closed timelike curves in the G\"{o}del-type
metric. By assuming a perfect fluid as the matter source, we find that the
fluid must have an equation of state parameter greater than minus one in order
to allow the G\"{o}del solutions to exist, and furthermore the critical radius
, beyond which the causality is broken down, is finite and it depends on
both matter and gravity. Remarkably, for certain models, the perfect
fluid that allows the G\"{o}del-type solutions can even be normal matter, such
as pressureless matter or radiation. However, if the matter source is a special
scalar field rather than a perfect fluid, then and the
causality violation is thus avoided.Comment: 18 pages, introduction revised, reference adde
X-ray Properties of LINERs and Low-luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results
This paper presents a comprehensive study of the X-ray properties of
low-ionization nuclear emission-line regions (LINERs) and low-luminosity
Seyfert galaxies based on observations obtained with ASCA. We analyzed data of
53 observations of 21 LINERs and 17 low-luminosity Seyferts. X-ray emission has
been detected in all but one object. The X-ray luminosities in the 2-10 keV
band range from 4e39 ergs/s to 5e41 ergs/s, which are 1-3 orders of magnitude
smaller than in classical Seyfert galaxies. The X-ray spectra of most objects
are well described by a canonical model which consists of (1) a soft component
from a thermal plasma with kT<1 keV and (2) a hard component represented by a
power law with a photon index~1.8 or thermal bremsstrahlung emission with kT~10
keV. Several objects do not require the soft thermal component, and their
continua are well fitted by a single power-law model. Some objects show heavy
absorption with column densities in excess of 1e23 cm^-2. We detect in several
objects Fe K line emission with equivalent widths ranging from 50 eV to 2 keV.
Variability on timescales less than a day is uncommon in our sample. By
comparing multiple observations made with ASCA or with published observations
from other satellites, we show that at least eight objects are variable on
timescales of a week to several years. We find that the morphologies of many
objects, both in the soft and hard bands, are consistent with being pointlike
relative to the telescope PSF; a few are clearly extended in either or both
energy bands.Comment: 38 pages, To appear in The Astrophysical Journal Supplements., v13
Teleparallel Killing Vectors of Spherically Symmetric Spacetimes
In this paper, Killing vectors of spherically spacetimes have been evaluated
in the context of teleparallel theory of gravitation. Further, we investigate
the Killing vectors of the Friedmann metrics. It is found that for static
spherically spacetimes the number of Killing vectors turn out to be
\emph{seven} while for the Friedmann models, we obtain \emph{six} teleparallel
Killing vectors. The results are then compared with those of General
Relativity. We conclude that both of these descriptions of gravity do not
provide the consistent results in general. However, these results may coincide
under certain conditions for a particular spacetime.Comment: 14 pages, accepted for publication in Communications in Theoretical
Physic
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