This paper uses a configurational perspective to examine high perceived value differentiation strategies of agribusiness in Latin America. Relying on information collected through interviews and a ...survey conducted with 200 firms, we explore the elements of the differentiation strategies adopted by the firms in this empirical context. We apply fsQCA to uncover asymmetric, complex causality. The findings provide interesting insights for scholars and practitioners alike, illustrating the strategic initiatives that the surveyed firms pursue to obtain higher perceived value than their competitors.
Neuropsychological profile of entrepreneurs Brenes, Esteban R.; Rodríguez, Gabriel; Acuña, Joseph ...
Academia (Consejo Latinoamericano de Escuelas de Administración),
10/2021, Volume:
34, Issue:
4
Journal Article
Peer reviewed
Purpose
By analyzing variables from the fields of business and neuropsychology, this document examines alternative combinations of behavioral economics and neuropsychological characteristics that ...would explain a successful entrepreneurial profile.
Design/methodology/approach
The research is based on information gathered through a survey of 1,080 entrepreneurs. The findings offer interesting perspectives for academics, professionals and government institutions, which illustrate various neuropsychological characteristics that a person must have to be a successful entrepreneur. The method consists of a novel perspective that integrates qualitative comparative analysis (QCAs), a method based on Boolean algebra that offers a study from a configurational perspective.
Findings
From the mixture of configurations, the paper explores following possible traits of an entrepreneurial mindset: cognitive flexibility, risk-taking, decision-making and teamwork.
Originality/value
This paper contributes to the literature on emerging attempts and approaches to understand the entrepreneurial mindset and the possible skillset that underpins successful entrepreneurship.
Propósito
Mediante el análisis de variables de los campos de los negocios y la neuropsicología, este documento examina combinaciones alternativas de la economía del comportamiento y las características neuropsicológicas que llevan a los emprendedores en perfiles exitosos.
Diseño/metodología/enfoque
La investigación se basa en información recopilada a través de una encuesta a 1.080 emprendedores. Los hallazgos ofrecen perspectivas interesantes para académicos, profesionales e instituciones gubernamentales, que ilustran diversas características neuropsicológicas que una persona debe tener para ser un emprendedor exitoso. El método consiste en una perspectiva novedosa que integra el análisis comparativo cualitativo (QCA), un método basado en el álgebra de Booleana que ofrece un estudio desde una perspectiva configuracional.
Hallazgos
A partir de la mezcla de configuraciones, el artículo explora los siguientes rasgos posibles de una mentalidad emprendedora: flexibilidad cognitiva, toma de riesgos, toma de decisiones y trabajo en equipo.
Originalidad/valor
este documento contribuye a la literatura sobre intentos y enfoques emergentes para comprender la mentalidad emprendedora y el posible conjunto de habilidades que sustenta el emprendimiento exitoso.
The efficient gas-phase photoreduction of Hg(II) has recently been shown to change mercury cycling significantly in the atmosphere and its deposition to the Earth’s surface. However, the photolysis ...of key Hg(I) species within that cycle is currently not considered. Here we present ultraviolet–visible absorption spectra and cross-sections of HgCl, HgBr, HgI, and HgOH radicals, computed by high-level quantum-chemical methods, and show for the first time that gas-phase Hg(I) photoreduction can occur at time scales that eventually would influence the mercury chemistry in the atmosphere. These results provide new fundamental understanding of the photobehavior of Hg(I) radicals and show that the photolysis of HgBr increases atmospheric mercury lifetime, contributing to its global distribution in a significant way.
Mercury (Hg), a global contaminant, is emitted mainly in its elemental form Hg⁰ to the atmosphere where it is oxidized to reactive HgII compounds, which efficiently deposit to surface ecosystems. ...Therefore, the chemical cycling between the elemental and oxidized Hg forms in the atmosphere determines the scale and geographical pattern of global Hg deposition. Recent advances in the photochemistry of gas-phase oxidized HgI and HgII species postulate their photodissociation back to Hg⁰ as a crucial step in the atmospheric Hg redox cycle. However, the significance of these photodissociation mechanisms on atmospheric Hg chemistry, lifetime, and surface deposition remains uncertain. Here we implement a comprehensive and quantitative mechanism of the photochemical and thermal atmospheric reactions between Hg⁰, HgI, and HgII species in a global model and evaluate the results against atmospheric Hg observations. We find that the photochemistry of HgI and HgII leads to insufficient Hg oxidation globally. The combined efficient photoreduction of HgI and HgII to Hg⁰ competes with thermal oxidation of Hg⁰, resulting in a large model overestimation of 99% of measured Hg⁰ and underestimation of 51% of oxidized Hg and ∼66% of HgII wet deposition. This in turn leads to a significant increase in the calculated global atmospheric Hg lifetime of 20 mo, which is unrealistically longer than the 3–6-mo range based on observed atmospheric Hg variability. These results show that the HgI and HgII photoreduction processes largely offset the efficiency of bromine-initiated Hg⁰ oxidation and reveal missing Hg oxidation processes in the troposphere.
Mercury is a contaminant of global concern that is transported throughout the atmosphere as elemental mercury Hg0 and its oxidized forms HgI and HgII. The efficient gas‐phase photolysis of HgII and ...HgI has recently been reported. However, whether the photolysis of HgII leads to other stable HgII species, to HgI, or to Hg0 and its competition with thermal reactivity remain unknown. Herein, we show that all oxidized forms of mercury rapidly revert directly and indirectly to Hg0 by photolysis. Results are based on non‐adiabatic dynamics simulations, in which the photoproduct ratios were determined with maximum errors of 3%. We construct for the first time a complete quantitative mechanism of the photochemical and thermal conversion between atmospheric HgII, HgI, and Hg0 compounds. These results reveal new fundamental chemistry that has broad implications for the global atmospheric Hg cycle. Thus, photoreduction clearly competes with thermal oxidation, with Hg0 being the main photoproduct of HgII photolysis in the atmosphere, which significantly increases the lifetime of this metal in the environment.
The ultimate fate of mercury in the atmosphere is elemental Hg. This result is based on non‐adiabatic dynamics simulations, which were used to construct a complete quantitative mechanism of the photochemical and thermal conversion of atmospheric HgII, HgI, and Hg0 compounds.
Small planets (∼1-3.9 ) constitute more than half of the inventory of the 4000-plus exoplanets discovered so far. Smaller planets are sufficiently dense to be rocky, but those with radii larger than ...∼1.6 are thought to display in many cases hydrogen/helium gaseous envelopes up to ∼30% of the planetary mass. These low-mass planets are highly irradiated and the question of their origin, evolution, and possible links remains open. Here we show that close-in ocean planets affected by the greenhouse effect display hydrospheres in supercritical state, which generate inflated atmospheres without invoking the presence of large hydrogen/helium gaseous envelopes. We present a new set of mass-radius relationships for ocean planets with different compositions and different equilibrium temperatures, which are found to be well adapted to low-density sub-Neptune planets. Our model suggests that super-Earths and water-rich sub-Neptunes could belong to the same family of planets, i.e., hydrogen/helium-free planets, with differences between their interiors simply resulting from the variation in the water content.
Graspetides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that exhibit an impressive diversity in patterns of side chain-to-side chain ω-ester or ω-amide ...linkages. Recent studies have uncovered a significant portion of graspetides to contain an additional post-translational modification involving aspartimidylation catalyzed by an O-methyltransferase, predominantly found in the genomes of actinomycetota. Here, we present a comprehensive bioinformatic analysis focused on graspetides harboring aspartimide, for which we propose the name graspimiditides. From protein BLAST results of 5000 methyltransferase sequences, we identified 962 unique putative graspimiditides, which we further classified into eight main clusters based on sequence similarity along with several smaller clusters and singletons. The previously studied graspimiditides, fuscimiditide, and amycolimiditide, are identified in this analysis; fuscimiditide is a singleton, while amycolimiditide is in the fifth largest cluster. Cluster 1, by far the largest cluster, contains 641 members, encoded almost exclusively in the Streptomyces genus. To characterize an example of a graspimiditide in Cluster 1, we conducted experimental studies on the peptide from Streptomyces albus J1074, which we named albusimiditide. By tandem mass spectrometry, hydrazinolysis, and amino acid substitution experiments, we elucidated the structure of albusimiditide to be a large tetracyclic peptide with four ω-ester linkages generating a stem-loop structure with one aspartimide. The ester cross-links form 22-, 46-, 22-, and 44-atom macrocycles, the last of which, the loop, contains the enzymatically installed aspartimide. Further in vitro experiments revealed that the aspartimide hydrolyzes in a 3:1 ratio of isoaspartate to aspartate residues. Overall, this study offers comprehensive insight into the diversity and structural features of graspimiditides, paving the way for future investigations of this unique class of natural products.
The Chemistry of Mercury in the Stratosphere Saiz‐Lopez, Alfonso; Acuña, A. Ulises; Mahajan, Anoop S. ...
Geophysical research letters,
28 June 2022, Volume:
49, Issue:
12
Journal Article
Peer reviewed
Open access
Mercury, a global contaminant, enters the stratosphere through convective uplift, but its chemical cycling in the stratosphere is unknown. We report the first model of stratospheric mercury chemistry ...based on a novel photosensitized oxidation mechanism. We find two very distinct Hg chemical regimes in the stratosphere: in the upper stratosphere, above the ozone maximum concentration, Hg0 oxidation is initiated by photosensitized reactions, followed by second‐step chlorine chemistry. In the lower stratosphere, ground‐state Hg0 is oxidized by thermal reactions at much slower rates. This dichotomy arises due to the coincidence of the mercury absorption at 253.7 nm with the ozone Hartley band maximum at 254 nm. We also find that stratospheric Hg oxidation, controlled by chlorine and hydroxyl radicals, is much faster than previously assumed, but moderated by efficient photo‐reduction of mercury compounds. Mercury lifetime shows a steep increase from hours in the upper‐middle stratosphere to years in the lower stratosphere.
Plain Language Summary
Mercury is a toxic pollutant that is released to the atmosphere as a result of human activities and from natural sources. Due to its long lifetime, mercury can travel around the world and also can be injected to the stratosphere via convective uplift in the tropical regions. Aircraft observations have reported significant concentrations of different forms of mercury in the stratosphere, however, the chemistry of mercury in this region of the atmosphere remains unexplored. This work reports a new chemical framework that sheds light on the chemical cycling of stratospheric mercury. The results reveal the stratosphere as a unique environment for mercury chemistry that has potential implications for the global transport of this metal.
Key Points
A new chemical mechanism for photosensitized mercury oxidation is proposed
Above the UV‐absorbing ozone layer, elemental mercury is quickly oxidized by photosensitized reactions
In the lower stratosphere, the photosensitized oxidation is replaced by much slower thermal oxidation driven by Cl, OH, and Br radicals
Instability remains the leading cause of revision following total hip arthroplasty (THA). The objective of the present investigation was to determine whether an elevated body mass index (BMI) is ...associated with an increased risk of instability after primary THA.
An administrative claims database was queried for patients undergoing elective, primary THA for osteoarthritis between 2010 and 2022. Patients who underwent THA for a femoral neck fracture were excluded. Patients who had an elevated BMI were grouped into the following cohorts: 25 to 29.9 (n = 2,313), 30 to 34.9 (n = 2,230), 35 to 39.9 (n = 1,852), 40 to 44.9 (n = 1,450), 45 to 49.9 (n = 752), and 50 to 59.9 (n = 334). Patients were matched 1:1 based on age, sex, and Elixhauser Comorbidity Index, as well as a history of spinal fusion, neurodegenerative disorders, and alcohol abuse, to controls with a normal BMI (20 to 24.9). A multivariate logistic regression controlling for age, sex, Elixhauser Comorbidity Index, and additional risk factors for dislocation was used to evaluate dislocation rates at 30 days, 90 days, 6 months, 1 year, and 2 years. Rates of revision for instability were similarly compared at 1 year and 2 years postoperatively.
No significant differences in dislocation rate were observed between control patients and each of the evaluated BMI classes at all evaluated postoperative intervals (all P values > .05). Similarly, the risk of revision for instability was comparable between the normal weight cohort and each evaluated BMI class at 1 year and 2 years postoperatively (all P values > .05).
Controlling for comorbidities and known risk factors for instability, the present analysis demonstrated no difference in rates of dislocation or revision for instability between normal-weight patients and those in higher BMI classes.
Abstract
We present a reanalysis of the K2-106 transiting planetary system, with a focus on the composition of K2-106b, an ultra-short-period, super-Mercury candidate. We globally model existing ...photometric and radial velocity data and derive a planetary mass and radius for K2-106b of
M
p
= 8.53 ± 1.02
M
⊕
and
R
p
=
1.71
−
0.057
+
0.069
R
⊕
, which leads to a density of
ρ
p
=
9.4
−
1.5
+
1.6
g cm
−3
, a significantly lower value than previously reported in the literature. We use planet interior models that assume a two-layer planet comprised of a liquid, pure Fe core and an iron-free, MgSiO
3
mantle, and we determine that the range of the core mass fractions are consistent with the observed mass and radius. We use existing high-resolution spectra of the host star to derive the Fe/Mg/Si abundances (Fe/H = −0.03 ± 0.01, Mg/H = 0.04 ± 0.02, Si/H = 0.03 ± 0.06) to infer the composition of K2-106b. We find that K2-106b has a density and core mass fraction (
44
−
15
+
12
%
) consistent with that of Earth (CMF
⊕
= 32%). Furthermore, its composition is consistent with what is expected, assuming that it reflects the relative refractory abundances of its host star. K2-106b is therefore unlikely to be a super-Mercury, as has been suggested in previous literature.
PDF
