bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ceo Pay and the Rise of Relative Performance Contracts: A Question of Governance?
Authors: Bell Brian , Pedemonte Simone , Van Reenen John 
Published: February 2021

Abstract
We exploit the large rise in relative performance awards in the United Kingdom over the last two decades to investigate whether these contracts improve the alignment between CEO pay and firm performance. We first document that corporate governance appears to be stronger when institutional ownership is greater. Then, using hand-collected data from annual reports on explicit contracts, we show that (1) CEO pay still responds more to increases in the firms’ stock performance than to decreases, and, importantly, this asymmetry is stronger when corporate governance is weak as measured by low institutional ownership; and (2) “pay for luck” persists as remuneration increases with random positive shocks, even when the CEO has equity awards that explicitly condition on firm performance relative to peer firms in the same sector. A major reason why relative performance contracts do not eliminate pay for luck is that CEOs who fail to meet the terms of their past performance awards are able to obtain more generous new equity rewards in the future in weakly governed firms. We show the mechanism operates both through the quantum of shares and the structure of new contracts. These findings suggest that reforms to the formal structure of CEO pay contracts are unlikely to align incentives in the absence of strong corporate governance.
Rapidly involuting congenital hemangioma of the liver in a newborn with incomplete Pentalogy of Cantrell: description of a new association
Authors: Gasparella Paolo , Singer Georg , Arneitz Christoph , Benesch Martin , Sorantin Erich , Kampelmühler Eva , Schemmer Peter , Till Holger 
Published: February 2021

Abstract
The perinatal management of newborns with giant omphaloceles requires careful suspicion concerning ‘unexpected’ associated malformations. We describe a newborn with a combination of incomplete Pentalogy of Cantrell consisting of giant omphalocele, anterior congenital diaphragmatic hernia (CDH) and pericardial absence complicated by a hepatic rapidly involuting congenital hemangioma (RICH). A giant omphalocele was detected prenatally. Postnatally, staged closure of the omphalocele was planned. A mass of the liver was noted and (mis-)taken for a hematoma. In the further course, the baby developed cardiorespiratory insufficiency due to a central CDH which was excised. Subsequently, staged closure of the omphalocele became impossible. Specific workup revealed a mass in the left liver lobe. The mass was resected and the abdominal wall defect repaired. Histology confirmed the diagnosis of an RICH. The surgical treatment of newborns with giant omphaloceles requires a multidisciplinary neonatal support and an elaborate pediatric surgical armamentarium to cope with additional malformations.
Face-on structure of barlenses and boxy bars: an insight from spectral dynamics
Authors: Smirnov Anton A , Tikhonenko Iliya S , Sotnikova Natalia Ya 
Published: February 2021

ABSTRACT
Based on the spectral analysis of individual orbits of stars from different N-body models, we show that the face-on morphology of the so-called ‘face-on peanut’ bars (boxy bars) and barlenses is supported by different types of orbits. For ‘face-on peanut’ bars, the so-called boxy orbits come to the fore, and they are responsible for the unusual morphology of the bar in the central regions. In the models with compact bulges, the bars show a barlens morphology in their central parts. We found that the barlens supporting orbits come in two types, one of which gives a square-like shape and the other have a rosette-like shape in the frame co-rotating with the bar. Such a shape is typical for orbits around stable loop orbits in nearly axisymmetric potentials only slightly distorted by the bar. They were already known from some of the previous studies but their role in barlens shaping was barely investigated. Although quite simple, the rosette-like orbits are found to be the main building block of a barlens in our models. The detailed analysis of all bar orbits also allowed us to distinguish the x2 orbital family and isolate the structure supported by orbits trapped around this family. The x2 family is well-known, but, apparently, for the first time in N-body models we have revealed the structure it supports by means of spectral dynamics and highlight its contribution to the barlens. We found that the x2 family population increases with an increase in central matter concentration.
The VVV open cluster project. Near-infrared sequences of NGC 6067, NGC 6259, NGC 4815, Pismis 18, Trumpler 23, and Trumpler 20
Authors: Peña Ramírez K , González-Fernández C , Chené A-N , Ramírez Alegría S 
Published: February 2021

ABSTRACT
Open clusters are central elements of our understanding of the Galactic disc evolution, as an accurate determination of their parameters leads to an unbiased picture of our Galaxy’s structure. Extending the analysis towards fainter magnitudes in cluster sequences has a significant impact on the derived fundamental parameters, such as extinction and total mass. We perform a homogeneous analysis of six open stellar clusters in the Galactic disc using kinematic and photometric information from the Gaia DR2 and VVV surveys: NGC 6067, NGC 6259, NGC 4815, Pismis 18, Trumpler 23, and Trumpler 20. We implement two coarse-to-fine characterization methods: first, we employ Gaussian mixture models to tag fields around each open cluster in the proper motion space, and then we apply an unsupervised machine learning method to make the membership assignment to each cluster. For the studied clusters, with ages in the ∼120–1900 Myr range, we report an increase of ∼45 per cent new member candidates on average in our sample. The data-driven selection approach of cluster members makes our catalogue a valuable resource for testing stellar evolutionary models and for assessing the cluster low-to-intermediate mass populations. This study is the first of a series intended to homogeneously reveal open cluster near-infrared sequences.
Rapid destruction of planetary debris around white dwarfs through aeolian erosion
Authors: Rozner Mor , Veras Dimitri , Perets Hagai B 
Published: February 2021

ABSTRACTThe discovery of numerous debris discs around white dwarfs (WDs) gave rise to extensive study of such discs and their role in polluting WDs, but the formation and evolution of these discs is not yet well understood. Here, we study the role of aeolian (wind) erosion in the evolution of solids in WD debris discs. Aeolian erosion is a destructive process that plays a key role in shaping the properties and size distribution of planetesimals, boulders, and pebbles in gaseous protoplanetary discs. Our analysis of aeolian erosion in WD debris discs shows that it can also play an important role in these environments. We study the effects of aeolian erosion under different conditions of the disc and its erosive effect on planetesimals and boulders of different sizes. We find that solid bodies smaller than $\sim \! 5 \, \rm {km}$ will be eroded within the short disc lifetime. We compare the role of aeolian erosion in respect to other destructive processes such as collisional fragmentation and thermal ablation. We find that aeolian erosion is the dominant destructive process for objects with radius $\lesssim \! 10^3 \, \rm {cm}$ and at distances $\lesssim \! 0.6 \, \mathrm{R}_\odot$ from the WD. Thereby, aeolian erosion constitutes the main destructive pathway linking fragmentational collisions operating on large objects with sublimation of the smallest objects and Poynting–Robertson drag, which leads to the accretion of the smallest particles on to the photosphere of WDs, and the production of polluted WDs.
τ9 Eri: a bright pulsating magnetic Bp star in a 5.95-d double-lined spectroscopic binary
Authors: Woodcock K , Wade G A , Kochukhov O , Sikora J , Pigulski A 
Published: February 2021

ABSTRACT
τ9 Eri is a Bp star that was previously reported to be a single-lined spectroscopic binary. Using 17 ESPaDOnS spectropolarimetric (Stokes V) observations, we identified the weak spectral lines of the secondary component and detected a strong magnetic field in the primary. We performed orbital analysis of the radial velocities of both components to find a slightly eccentric orbit (e = 0.129) with a period of 5.95382(2) d. The longitudinal magnetic field (Bℓ) of the primary was measured from each of the Stokes V profiles, with typical error bars smaller than 10 G. Equivalent widths (EWs) of least-squares deconvolution profiles corresponding to only the Fe lines were also measured. We performed frequency analysis of both the Bℓ and EW measurements, as well as of the Hipparcos, SMEI, and TESS photometric data. All sets of photometric observations produce two clear, strong candidates for the rotation period of the Bp star: 1.21 and 3.82 d. The Bℓ and EW measurements are consistent with only the 3.82-d period. We conclude that HD 25267 consists of a late-type Bp star (M = $3.6_{-0.2}^{+0.1}~\mathrm{ M}_\odot$, T = $12580_{-120}^{+150}$ K) with a rotation period of 3.82262(4) d orbiting with a period of 5.95382(2) d with a late-A/early-F type secondary companion (M = 1.6 ± 0.1 M⊙, T = $7530_{-510}^{+580}$ K). The Bp star’s magnetic field is approximately dipolar with i = 41 ± 2°, β = 158 ± 5°, and Bd = 1040 ± 50 G. All evidence points to the strong 1.209912(3)-d period detected in photometry, along with several other weaker photometric signals, as arising from g-mode pulsations in the primary.
Impact of magnetic activity on inferred stellar properties of main-sequence Sun-like stars
Authors: Thomas Alexandra E L , Chaplin William J , Basu Sarbani , Rendle Ben , Davies Guy , Miglio Andrea 
Published: February 2021

ABSTRACT
The oscillation frequencies observed in Sun-like stars are susceptible to being shifted by magnetic activity effects. The measured shifts depend on a complex relationship involving the mode type, the field strength, and spatial distribution of activity, as well as the inclination angle of the star. Evidence of these shifts is also present in frequency separation ratios that are often used when inferring global properties of stars in order to avoid surface effects. However, one assumption when using frequency ratios for this purpose is that there are no near-surface perturbations that are non-spherically symmetric. In this work, we studied the impact on inferred stellar properties when using frequency ratios that are influenced by non-homogeneous activity distributions. We generate several sets of artificial oscillation frequencies with various amounts of shift and determine stellar properties using two separate pipelines. We find that for asteroseismic observations of Sun-like targets we can expect magnetic activity to affect mode frequencies that will bias the results from stellar modelling analysis. Although for most stellar properties this offset should be small, typically less than 0.5 per cent in mass, estimates of age and central hydrogen content can have an error of up to 5 per cent and 3 per cent, respectively. We expect a larger frequency shift and therefore larger bias for more active stars. We also warn that for stars with very high or low inclination angles, the response of modes to activity is more easily observable in the separation ratios and hence will incur a larger bias.
The theory of cosmic ray scattering on pre-existing MHD modes meets data
Authors: Fornieri Ottavio , Gaggero Daniele , Cerri Silvio Sergio , De La Torre Luque Pedro , Gabici Stefano 
Published: February 2021

ABSTRACT
We present a comprehensive study about the phenomenological implications of the theory describing Galactic cosmic ray scattering on to magnetosonic and Alfvénic fluctuations in the GeV−PeV domain. We compute a set of diffusion coefficients from first principles, for different values of the Alfvénic Mach number and other relevant parameters associated with both the Galactic halo and the extended disc, taking into account the different damping mechanisms of turbulent fluctuations acting in these environments. We confirm that the scattering rate associated with Alfvénic turbulence is highly suppressed if the anisotropy of the cascade is taken into account. On the other hand, we highlight that magnetosonic modes play a dominant role in Galactic confinement of cosmic rays up to PeV energies. We implement the diffusion coefficients in the numerical framework of the dragon code, and simulate the equilibrium spectrum of different primary and secondary cosmic ray species. We show that, for reasonable choices of the parameters under consideration, all primary and secondary fluxes at high energy (above a rigidity of $\simeq 200 \, \mathrm{GV}$) are correctly reproduced within our framework, in both normalization and slope.
Dust evolution in zoom-in cosmological simulations of galaxy formation
Authors: Granato Gian Luigi , Ragone-Figueroa Cinthia , Taverna Antonela , Silva Laura , Valentini Milena , Borgani Stefano , Monaco Pierluigi , Murante Giuseppe , Tornatore Luca 
Published: February 2021

ABSTRACT
We present cosmological zoom-in hydrodynamical simulations for the formation of disc galaxies, implementing dust evolution and dust promoted cooling of hot gas. We couple an improved version of our previous treatment of dust evolution, which adopts the two-size approximation to estimate the grain-size distribution, with the MUPPI star formation and feedback subresolution model. Our dust evolution model follows carbon and silicate dust separately. To distinguish differences induced by the chaotic behaviour of simulations from those genuinely due to different simulation set-up, we run each model six times, after introducing tiny perturbations in the initial conditions. With this method, we discuss the role of various dust-related physical processes and the effect of a few possible approximations adopted in the literature. Metal depletion and dust cooling affect the evolution of the system, causing substantial variations in its stellar, gas, and dust content. We discuss possible effects on the Spectral Energy Distribution of the significant variations of the size distribution and chemical composition of grains, as predicted by our simulations during the evolution of the galaxy. We compare dust surface density, dust-to-gas ratio, and small-to-large grain mass ratio as a function of galaxy radius and gas metallicity predicted by our fiducial run with recent observational estimates for three disc galaxies of different masses. The general agreement is good, in particular taking into account that we have not adjusted our model for this purpose.
The kinematic richness of star clusters – II. Stability of spherical anisotropic models with rotation
Authors: Breen Philip G , Rozier Simon , Heggie Douglas C , Varri Anna Lisa 
Published: February 2021

ABSTRACT
We study the bar instability in collisionless, rotating, anisotropic, stellar systems, using N-body simulations and also the matrix technique for calculation of modes with the perturbed collisionless Boltzmann equation. These methods are applied to spherical systems with an initial Plummer density distribution, but modified kinematically in two ways: the velocity distribution is tangentially anisotropic, using results of Dejonghe, and the system is set in rotation by reversing the velocities of a fraction of stars in various regions of phase space, à la Lynden-Bell. The aim of the N-body simulations is first to survey the parameter space, and, using those results, to identify regions of phase space (by radius and orbital inclination) that have the most important influence on the bar instability. The matrix method is then used to identify the resonant interactions in the system that have the greatest effect on the growth rate of a bar. Complementary series of N-body simulations examine these processes in relation to the evolving frequency distribution and the pattern speed. Finally, the results are synthesized with an existing theoretical framework, and used to consider the old question of constructing a stability criterion.
Where is the genusElysiain the western Atlantic? Potential distribution, species richness and representation in marine protected areas
Authors: Jiménez Lina Marcela , Simões Nuno , Yáñez-Arenas Carlos 
Published: February 2021

ABSTRACTThe western Atlantic Ocean is one of the areas with the largest species richness of sea slugs in the genus Elysia (30 out of the 101 species described have been reported in this region). Nevertheless, the lack of knowledge on many of these species hinders efforts to estimate regional richness and identify the factors affecting their distribution. We used the maximum entropy algorithm Maxent to develop ecological niche models for 14 species of Elysia in the western Atlantic Ocean. These models were meant to show the potential distribution of the genus and identify locations with the highest richness. Input data used to build niche models were presence records (obtained from several sources) and bioclimatic and geophysical variables from the Bio-ORACLE and MARSPEC platforms. Species with less than seven records were considered for the calculation of richness, but not for modelling. Results show low habitat suitability for the species modelled here at the mouth of rivers and in hypoxic zones and low-temperature areas. The two variables that best explained species distribution patterns were the distance to shore and the maximum monthly temperature. From the total area with adequate environmental conditions for the genus, only 20.3% is located within marine areas under some protection category.
Heterogeneity of Recent Phase 3 Complicated Urinary Tract Infection Clinical Trials
Authors: Portsmouth Simon , Bass Almasa , Echols Roger , Tillotson Glenn 
Published: February 2021

Abstract

Background
For new antibiotics developed to treat antibiotic-resistant Gram-negative infections, the US Food and Drug Administration (FDA) regulatory pathway includes complicated urinary tract infection (cUTI) clinical trials in which the clinical isolates are susceptible to the active control. This allows for inferential testing in a noninferiority study design. Although complying with regulatory guidelines, individual clinical trials may differ substantially in design and patient population. To determine variables that impacted patient selection and outcome parameters, 6 recent cUTI trials that were pivotal to an new drug application (NDA) submission were reviewed.

Methods
This selective descriptive analysis utilized cUTI trial data, obtained from publicly disclosed information including FDA documents and peer-reviewed publications, from 6 new antibiotics developed to treat multidrug-resistant Gram-negative infections: ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, cefiderocol, plazomicin, and fosfomycin. Eravacycline was not approved for cUTI and is not included.

Results
Microbiologic modified intent-to-treat sample size, age, proportions of female patients, acute pyelonephritis (AP), Escherichia coli and other pathogens at baseline, protocol-specified switch to oral antibiotic, and the noninferiority margin were compared. Outcome data included clinical response, microbiologic eradication, and composite outcomes, including a subset of patients with AP.

Conclusions
A study design can follow regulatory guidelines but still have variable populations. The proportion of AP within a study varied greatly and influenced population demographics (age, gender) and baseline microbiology. A smaller proportion of AP resulted in an older patient population, fewer females, less E coli, and lower proportions of patients achieving success. Fluoroquinolones and piperacillin/tazobactam should be reconsidered as active comparators given the high rates of resistance to these antibiotics.
Disentangling the Coronavirus Disease 2019 Health Disparities in African Americans: Biological, Environmental, and Social Factors
Authors: Saini Geetanjali , Swahn Monica H , Aneja Ritu 
Published: February 2021

AbstractThe stark racial disparities related to the coronavirus disease 2019 (COVID-19) pandemic in the United States, wherein minority populations are disproportionately getting infected and succumbing to the disease, is of grave concern. It is critical to understand and address the underlying causes of these disparities that are complex and driven by interacting environmental, social and biological factors. In this article we focus on the African American community and examine how social and environmental determinants of health intersect with biological factors (comorbidities, underlying genetics, host immunity, vitamin D levels, epigenetics) to exacerbate risk for morbidity and mortality.
Relative Frequency and Risk Factors of COVID-19 Related Headache in a Sample of Egyptian Population: A Hospital-Based Study
Authors: Hussein Mona , Fathy Wael , Eid Ragaey A , Abdel-Hamid Hoda M , Yehia Ahmed , Sheemy Mostafa S , Ragaie Christine , Dahshan Ahmed , Rizk Hoda I , laz Nabila , Magdy Rehab 
Published: February 2021

Abstract

Objectives
Headache is considered one of the most frequent neurological manifestations of coronavirus disease 2019 (COVID-19). This work aimed to identify the relative frequency of COVID-19-related headache and to clarify the impact of clinical, laboratory findings of COVID-19 infection on headache occurrence and its response to analgesics.

Design
Cross-sectional study.

Setting
Recovered COVID-19 patients.

Subjects
In total, 782 patients with a confirmed diagnosis of COVID-19 infection.

Methods
Clinical, laboratory, and imaging data were obtained from the hospital medical records. Regarding patients who developed COVID-19 related headache, a trained neurologist performed an analysis of headache and its response to analgesics.

Results
The relative frequency of COVID-19 related headache among our sample was 55.1% with 95% confidence interval (CI) (.516–.586) for the estimated population prevalence. Female gender, malignancy, primary headache, fever, dehydration, lower levels of hemoglobin and platelets and higher levels of neutrophil/lymphocyte ratio (NLR) and CRP were significantly associated with COVID-19 related headache. Multivariate analysis revealed that female gender, fever, dehydration, primary headache, high NLR, and decreased platelet count were independent predictors of headache occurrence. By evaluating headache response to analgesics, old age, diabetes, hypertension, primary headache, severe COVID-19, steroid intake, higher CRP and ferritin and lower hemoglobin levels were associated with poor response to analgesics. Multivariate analysis revealed that primary headache, steroids intake, moderate and severe COVID-19 were independent predictors of non-response to analgesics.

Discussion
Headache occurs in 55.1% of patients with COVID-19. Female gender, fever, dehydration, primary headache, high NLR, and decreased platelet count are considered independent predictors of COVID-19 related headache.