Search results for " effects"
showing 10 items of 2364 documents
Mast cells promote homeostasis by limiting endothelin-1-induced toxicity
2004
Endothelin-1 (ET-1) is a 21-amino-acid peptide, derived from vascular endothelial cells, with potent vasoconstrictor activity. ET-1 has been implicated in diverse physiological or pathological processes, including the vascular changes associated with sepsis. However, the factors that regulate ET-1-associated toxicity during bacterial infections, or in other settings, are not fully understood. Both the pathology associated with certain allergic and autoimmune disorders, and optimal host defence against bacterial and parasitic infections are mediated by mast cells. In vitro, mast cells can produce ET-1 (ref. 11), undergo ET-1-dependent and endothelin-A receptor (ET(A))-dependent activation, a…
El rol del modelo de las competencias en la reconfiguración meritocrática de las pautas de negociación salarial en empresas argentinas: continuidades…
2020
The development of new models of work organization and the complementary advance of flexible guidelines for the use of the labor force had as a correlate a profound change in techniques for the evaluation of workers. Thus, the typical model of Fordism, based on qualifications, was replaced by a different one based on competencies, whereby the strong relationship of the former was abandoned with the determination of the technical knowledge required for each job to move to a system which the priority is placed in the individual attitude. The consequent individualization of performance evaluations can lead to a possible loss of objectivity. In this article we develop a theoretical comparison b…
R&D subsidies & external collaborative breadth: Differential gains and the role of collaboration experience
2018
The file attached to this record is the author's final peer reviewed version. External collaboration breadth is important for firms to acquire the knowledge needed to innovate. In this paper, we combine cross-sectional and longitudinal data from the Spanish Panel of Technological Innovation Survey (PITEC) to examine the indirect impact of R&D subsidies on firm external collaboration breadth. We contribute to understanding of the indirect impacts of R&D subsidies by first providing strong evidence of an economically significant average positive impact of R&D subsidies on firm external collaboration breadth. Second, our results advance understanding of the differential impacts of R&D subsidie…
The contribution of geographical certification programs to farm income and rural economies: The case of Pecorino Siciliano PDO
2021
This study attempts to measure the capacity of the EU geographical certification scheme to positively influence the price of certified products and the incomes of their producers. A comparison of the economic results of two cheese-producing dairy farm enterprises with different business strategies and locations within the Sicilian hinterlands is performed in order to determine the transformation value of each dairy’s sheep milk into pecorino cheese (with and without the Protected Designation of Origin, or PDO, certification) and the related joint products (ricotta). The economic convenience of the total transformation of sheep milk into Pecorino Siciliano PDO and ricotta is also appraised. …
High-pressure theoretical and experimental study of HgWO4
2011
HgWO 4 at ambient pressure is characterized using a combination of ab initio calculations, X-ray diffraction and Raman scattering measurements. The effect of low pressure and temperature on the structural stability is analysed. Extending our ab initio study to the range of higher pressures, a sequence of stable phases up to 30GPa is proposed. © 2011 Taylor & Francis.
Effect of Substituents on the Molecular Shapes of π-Basic Macrotricyclic Receptors
2010
Molecular recognition between receptor and substrate is optimized when these compounds show complementary shapes, sizes, and interacting moieties. A family of C3v-symmetric macrotricycles 1–4 is presented that incorporate resorcinol- and mesitylene-derived “walls” and “cap”, respectively. These compounds feature, in principle, a tetrahedral π-basic cavity. This paper reports the effect of substituents in the “walls” and the “cap” on the shapes of the macrotricycles in solution (1H NMR), the solid state (X-ray diffraction), and gas phase (calculations). Substitution of the lower position of the “walls” by Br (in 3) or MeS (in 4) has the same effect as ethyl substitution of the “cap” (in 2), …
Analysis of the Diffusion-Induced Stress Effect on the Oxidation in Finely Divided Vanadium Ferrites
1999
L'oxydation isotherme des cations fer(II), vanadium(II) et vanadium(III) pour les ferrites spinelles finement divises, lesquels sont oxydes en phases deficitaires en cations, a ete etudiee par thermogravimetrie. La faible temperature de cinetique d'oxydation de chaque cation oxydable a ete expliquee en considerant que l'oxydation genere des contraintes qui en modifie la cinetique ou les cations a la surface sont plus oxydes que dans le volume. Pour cela, il at ete considere que le coefficient de diffusion chimique est donne par la relation D = D 0 exp [-(E' a + pV a )/RT] ou D 0 represente le facteur pre-exponentiel, E' a l'energie d'activation, V a le volume d'activation et p la pression i…
A remarkable rearrangement during reaction between triazolopyridinium ylides and dimethyl acetylenedicarboxylate
1991
Abstract The ylides from 2-acylmethyltriazolopyridinium salts ( 1 ) react with dimethyl acetylenedicarboxylate in toluene solution to give the 7-pyrroleninylpyrazolo[1,5-a]pyridines ( 5 ).
Toward an Understanding of the Molecular Mechanism of the Reaction between 1-Methylpyrrole and Dimethyl Acetylenedicarboxylate. An ab Initio Study
1998
The molecular mechanism for the reaction between 1-methylpyrrole and dimethyl acetylenedicarboxylate (DMAD) has been studied using ab initio methods. Two alternative reaction pathways have been considered, both of which correspond to stepwise processes with initial, rate-determining formation of a common zwitterionic intermediate. This intermediate is formed by nucleophilic attack of the pyrrole ring to the carbon−carbon triple bond of DMAD. Closure of this intermediate (pathway A) affords a [4 + 2] cycloadduct, whereas intramolecular proton transfer (pathway B) affords a Michael adduct. The much larger potential energy barrier of the second step in pathway B relative to pathway A is respon…
Discrete Derivatives for Atom-Pairs as a Novel Graph-Theoretical Invariant for Generating New Molecular Descriptors: Orthogonality, Interpretation an…
2013
This report presents a new mathematical method based on the concept of the derivative of a molecular graph (G) with respect to a given event (S) to codify chemical structure information. The derivate over each pair of atoms in the molecule is defined as ∂G/∂S(vi , vj )=(fi -2fij +fj )/fij , where fi (or fj ) and fij are the individual frequency of atom i (or j) and the reciprocal frequency of the atoms i and j, respectively. These frequencies characterize the participation intensity of atom pairs in S. Here, the event space is composed of molecular sub-graphs which participate in the formation of the G skeleton that could be complete (representing all possible connected sub-graphs) or comp…