17,625 research outputs found
Does Institutional Context Affect CSR Disclosure? A Study on Eurostoxx 50
We propose to investigate the relationship between corporate social responsibility disclosure and institutional/environmental factors among a sample of European listed companies. We find that, by using several traditional explicative variables, institutional factors affect the level of CSR disclosure, in a context where the EU Commission has been paying growing attention to social and environmental accountability of listed companies (see the EU Dir. 95/2014). Our findings are further supported by multivariate regression, where ESG score (measure of CSR disclosure) is regressed on nine variables which represent the expression of institutional factors. By looking at the institutional
determinants of CSR disclosure, we are seeking to pose a challenge for future research agenda, in order to understand whether CSR does actually reflect an effective commitment of firms to accounting practices and rules, as a form of social behavior, or whether it is just a tool to manage stakeholders’ perception and to comply with regulation
More on ambiguities in the pole mass
The relation between the pole quark mass and the -renormalized
mass is governed by an infrared renormalon singularity, which leads to an
ambiguity of order in the definition of the pole mass. We use
the renormalization group and heavy quark effective theory to determine the
exact nature of this singularity up to an overall normalization. In the abelian
gauge theory, the normalization is computed partially to next-to-leading order
in the flavour expansion.Comment: LaTeX, 10 pages, Figures appended as uu-encoded file, UM-TH-94-3
The Clustering of AGN in the Sloan Digital Sky Survey
We present the two--point correlation function (2PCF) of narrow-line active
galactic nuclei (AGN) selected within the First Data Release of the Sloan
Digital Sky Survey. Using a sample of 13605 AGN in the redshift range 0.055 < z
< 0.2, we find that the AGN auto--correlation function is consistent with the
observed galaxy auto--correlation function on scales 0.2h^{-1}Mpc to
>100h^{-1}Mpc. The AGN hosts trace an intermediate population of galaxies and
are not detected in either the bluest (youngest) disk--dominated galaxies or
many of the reddest (oldest) galaxies. We show that the AGN 2PCF is dependent
on the luminosity of the narrow [OIII] emission line (L_{[OIII]}), with low
L_{[OIII]} AGN having a higher clustering amplitude than high L_{[OIII]} AGN.
This is consistent with lower activity AGN residing in more massive galaxies
than higher activity AGN, and L_{[OIII]} providing a good indicator of the
fueling rate. Using a model relating halo mass to black hole mass in
cosmological simulations, we show that AGN hosted by ~ 10^{12} M_{odot} dark
matter halos have a 2PCF that matches that of the observed sample. This mass
scale implies a mean black hole mass for the sample of M_{BH} ~ 10^8 M_{odot}.Comment: 5 pages, 4 figures. Accepted for publication in ApJ
A precise determination of the Bc mass from dynamical lattice QCD
We perform a precise calculation of the mass of the B_c meson using
unquenched configurations from the MILC collaboration including 2+1 flavours of
improved staggered quarks. Lattice NRQCD and the Fermilab formalism are used to
describe the b and c quarks respectively. We find the mass of the B_c meson to
be 6.304(16) GeVComment: Talk presented at Lattice2004(heavy), Fermilab, June 21-26. 3 pages,
2 figure
Bayesian approach to SETI
The search for technosignatures from hypothetical galactic civilizations is
going through a new phase of intense activity. For the first time, a
significant fraction of the vast search space is expected to be sampled in the
foreseeable future, potentially bringing informative data about the abundance
of detectable extraterrestrial civilizations, or the lack thereof. Starting
from the current state of ignorance about the galactic population of
non-natural electromagnetic signals, we formulate a Bayesian statistical model
to infer the mean number of radio signals crossing Earth, assuming either
non-detection or the detection of signals in future surveys of the Galaxy.
Under fairly noninformative priors, we find that not detecting signals within
about kly from Earth, while suggesting the lack of galactic emitters or at
best the scarcity thereof, is nonetheless still consistent with a probability
exceeding \% that typically over signals could be crossing
Earth, with radiated power analogous to that of the Arecibo radar, but coming
from farther in the Milky Way. The existence in the Galaxy of potentially
detectable Arecibo-like emitters can be reasonably ruled out only if all-sky
surveys detect no such signals up to a radius of about kly, an endeavor
requiring detector sensitivities thousands times higher than those of current
telescopes. Conversely, finding even one Arecibo-like signal within
light years, a possibility within reach of current detectors, implies almost
certainly that typically more than signals of comparable radiated
power cross the Earth, yet to be discovered.Comment: Published in PNAS ahead of print October 1, 2018. Preprint has 13
pages, 7 figures + 7 pages of Supplementary Information with 5 figure
A High Statistics Lattice Calculation of The B-meson Binding Energy
We present a high statistics lattice calculation of the B--meson binding
energy of the heavy--quark inside the pseudoscalar
B--meson. Our numerical results have been obtained from several independent
numerical simulations at , and , and using, for the meson
correlators, the results obtained by the APE group at the same values of
. Our best estimate, obtained by combining results at different values
of , is MeV. For the
running mass, we obtain
GeV, in reasonable
agreement with previous determinations. The systematic error is the truncation
of the perturbative series in the matching condition of the relevant operator
of the Heavy Quark Effective Theory.Comment: Latex, 13 pages, 1 figure appended in uuencoded gzip.tar.fil
Electron Tunneling in Single Crystals of Pseudomonas aeruginosa Azurins
Rates of reduction of Os(III), Ru(III), and Re(I)^* by Cu(I) in His83-modified Pseudomonas aeruginosa azurins (M−Cu distance ∼17 Å) have been measured in single crystals, where protein conformation and surface solvation are precisely defined by high-resolution X-ray structure determinations: 1.7(8) × 10^6 s^(-1) (298 K), 1.8(8) × 10^6 s^(-1) (140 K), [Ru(bpy)_2(im)^(3+)-]; 3.0(15) × 10^6 s^(-1) (298 K), [Ru(tpy)(bpy)^(3+)-]; 3.0(15) × 10^6 s^(-1) (298 K), [Ru(tpy)(phen)^(3+)-]; 9.0(50) × 10^2 s^(-1) (298 K), [Os(bpy)2(im)^(3+)-]; 4.4(20) × 10^6 s^(-1) (298 K), [Re(CO)_3(phen)^(+*)] (bpy = 2,2‘-bipyridine; im = imidazole; tpy = 2,2‘:6‘,2‘ ‘-terpyridine; phen = 1,10-phenanthroline). The time constants for electron tunneling in crystals are roughly the same as those measured in solution, indicating very similar protein structures in the two states. High-resolution structures of the oxidized (1.5 Å) and reduced (1.4 Å) states of Ru(II)(tpy)(phen)(His83)Az establish that very small changes in copper coordination accompany reduction but reveal a shorter axial interaction between copper and the Gly45 peptide carbonyl oxygen [2.6 Å for Cu(II)] than had been recognized previously. Although Ru(bpy)_2(im)(His83)Az is less solvated in the crystal, the reorganization energy for Cu(I) → Ru(III) electron transfer falls in the range (0.6−0.8 eV) determined experimentally for the reaction in solution. Our work suggests that outer-sphere protein reorganization is the dominant activation component required for electron tunneling
The role of the emergency department in the management of acute heart failure: an international perspective on education and research
Emergency departments are a major entry point for the initial management of acute heart failure (AHF) patients throughout the world. The initial diagnosis, management and disposition - the decision to admit or discharge - of AHF patients in the emergency department has significant downstream implications. Misdiagnosis, under or overtreatment, or inappropriate admission may place patients at increased risk for adverse events, and add costs to the healthcare system. Despite the critical importance of initial management, data are sparse regarding the impact of early AHF treatment delivered in the emergency department compared to inpatient or chronic heart failure management. Unfortunately, outcomes remain poor, with nearly a third of patients dying or re-hospitalised within 3 months post-discharge. In the absence of robust research evidence, consensus is an important source of guidance for AHF care. Thus, we convened an international group of practising emergency physicians, cardiologists and advanced practice nurses with the following goals to improve outcomes for AHF patients who present to the emergency department or other acute care setting through: (a) a better understanding of the pathophysiology, presentation and management of the initial phase of AHF care; (b) improving initial management by addressing knowledge gaps between best practices and current practice through education and research; and (c) to establish a framework for future emergency department-based international education and research
Recommended from our members
Calibration strategies for use of the nanoDot OSLD in CT applications.
Aluminum oxide based optically stimulated luminescent dosimeters (OSLD) have been recognized as a useful dosimeter for measuring CT dose, particularly for patient dose measurements. Despite the increasing use of this dosimeter, appropriate dosimeter calibration techniques have not been established in the literature; while the manufacturer offers a calibration procedure, it is known to have relatively large uncertainties. The purpose of this work was to evaluate two clinical approaches for calibrating these dosimeters for CT applications, and to determine the uncertainty associated with measurements using these techniques. Three unique calibration procedures were used to calculate dose for a range of CT conditions using a commercially available OSLD and reader. The three calibration procedures included calibration (a) using the vendor-provided method, (b) relative to a 120 kVp CT spectrum in air, and (c) relative to a megavoltage beam (implemented with 60 Co). The dose measured using each of these approaches was compared to dose measured using a calibrated farmer-type ion chamber. Finally, the uncertainty in the dose measured using each approach was determined. For the CT and megavoltage calibration methods, the dose measured using the OSLD nanoDot was within 5% of the dose measured using an ion chamber for a wide range of different CT scan parameters (80-140 kVp, and with measurements at a range of positions). When calibrated using the vendor-recommended protocol, the OSLD measured doses were on average 15.5% lower than ion chamber doses. Two clinical calibration techniques have been evaluated and are presented in this work as alternatives to the vendor-provided calibration approach. These techniques provide high precision for OSLD-based measurements in a CT environment
Relaxation Dynamics of Pseudomonas aeruginosa Re^I(C)O_3(α-diimine)(HisX)^+ (X=83, 107, 109, 124, 126)Cu-^(II) Azurins
Photoinduced relaxation processes of five structurally characterized Pseudomonas aeruginosa Re^I(CO)_3(α-diimine)(HisX) (X = 83, 107, 109, 124, 126)Cu^(II) azurins have been investigated by time-resolved (ps−ns) IR spectroscopy and emission spectroscopy. Crystal structures reveal the presence of Re-azurin dimers and trimers that in two cases (X = 107, 124) involve van der Waals interactions between interdigitated diimine aromatic rings. Time-dependent emission anisotropy measurements confirm that the proteins aggregate in mM solutions (D2O, KPi buffer, pD = 7.1). Excited-state DFT calculations show that extensive charge redistribution in the ReI(CO)_3 → diimine ^3MLCT state occurs: excitation of this ^3MLCT state triggers several relaxation processes in Re-azurins whose kinetics strongly depend on the location of the metallolabel on the protein surface. Relaxation is manifested by dynamic blue shifts of excited-state ν(CO) IR bands that occur with triexponential kinetics: intramolecular vibrational redistribution together with vibrational and solvent relaxation give rise to subps, 2, and 8−20 ps components, while the ~10^2 ps kinetics are attributed to displacement (reorientation) of the Re^I(CO)_3(phen)(im) unit relative to the peptide chain, which optimizes Coulombic interactions of the Re^I excited-state electron density with solvated peptide groups. Evidence also suggests that additional segmental movements of Re-bearing β-strands occur without perturbing the reaction field or interactions with the peptide. Our work demonstrates that time-resolved IR spectroscopy and emission anisotropy of Re^I carbonyl−diimine complexes are powerful probes of molecular dynamics at or around the surfaces of proteins and protein−protein interfacial regions
- …
