Search results for "action"

Water in stereoselective organocatalytic reactions

2009

In this review, recent advances in asymmetric organocatalytic reactions carried out with variable amounts of water, from substoichiometric to a large excess (reaction medium), are discussed. We also summarize several proposed mechanisms for the different possibilities of the action of water both in the increased activity of the catalyst and in the asymmetric induction. Finally, the application of this catalytic methodology to the enantioselective synthesis of valuable compounds through enamine or iminium catalysis is presented.

Chemical weathering of volcanic rocks, Pantelleria Island: information from soil profile and soil solution investigations

2007

Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state of primar…

The mechanically based non-local elasticity: an overview of main results and future challenges

2013

The mechanically based non-local elasticity has been used, recently, in wider and wider engineering applications involving small-size devices and/or materials with marked microstructures. The key feature of the model involves the presence of non-local effects as additional body forces acting on material masses and depending on their relative displacements. An overview of the main results of the theory is reported in this paper.

Atmospheric circulation modulates the spatial variability of temperature in the Atlantic-Arctic region

2019

International audience; The Arctic region has experienced significant warming during the past two decades with major implications on the cryosphere. The causes of Arctic amplification are still an open question within the scientific community, attracting recent interest. The goal of this study is to quantify the contribution of atmospheric circulation on temperature variability in the Atlantic–Arctic region at decadal to intra‐annual timescales from 1951 to 2014. Daily 20th Century reanalyses geopotential height anomalies at 500 hPa were clustered into different weather regimes to assess their contribution to observed temperature variability. The results show that in winter, 25% of the warm…

A Comparative Eye Tracking Study of Usability—Towards Sustainable Web Design

2021

Websites are one of the most frequently used communication environments, and creating sustainable web designs should be an objective for all companies. Ensuring high usability is proving to be one of the main contributors to sustainable web design, reducing usage time, eliminating frustration and increasing satisfaction and retention. The present paper studies the usability of different website landing pages, seeking to identify the elements, structures and designs that increase usability. The study analyzed the behavior of 22 participants during their interaction with five different landing pages while they performed three tasks on the webpage and freely viewed each page for one minute. Th…

A New Phylogenetic Framework for the Animal-Adapted

2018

Tuberculosis (TB) affects humans and other animals and is caused by bacteria from the Mycobacterium tuberculosis complex (MTBC). Previous studies have shown that there are at least nine members of the MTBC infecting animals other than humans; these have also been referred to as ecotypes. However, the ecology and the evolution of these animal-adapted MTBC ecotypes are poorly understood. Here we screened 12,886 publicly available MTBC genomes and newly sequenced 17 animal-adapted MTBC strains, gathering a total of 529 genomes of animal-adapted MTBC strains. Phylogenomic and comparative analyses confirm that the animal-adapted MTBC members are paraphyletic with some members more closely relate…

Evaluation of biocidal potential of some plant species from the Mediterranean wild flora

Fractional calculus approach for the representation of power spectral densities and correlation functions in wind engineering

2010

The paper deals with the digital simulation of wind velocity samples by Fractional Spectral Moment function. It is shown that such a function represents a third useful way to characterize a stationary Gaussian stochastic process, alongside the power spectral density and the correlation function. The method is applied to wind velocity fields whose power spectra is given by the Kaimal’s, the Davenport’s and the Solari’s representation. It is shown that by constructing a digital filter whose coefficients are the fractional spectral moments, it is possible to simulate samples of the target process as superposition of Riesz fractional derivatives of Gaussian white noise processes.

Antecedents and consequences of perceived investment value

2014

To gain a more comprehensive view to non-institutional investment behavior, this study develops and tests a set of hypotheses linking self-congruence, risk profile and investment experience with perceived investment value (PIV). In addition, the study tests direct and indirect effects of PIV on positive word-of-mouth. The hypotheses are tested on data from 440 private investors. The findings reveal that 1) self-congruence and risk profile are positively associated with five out of six of the PIV dimensions, 2) the relationship between PIV and word-of-mouth are more complex than is generally thought, and 3) user experience moderates four out of the twelve hypothesized paths. The study contri…

Assessment of Occupational Health and Job Satisfaction in Workers with Intellectual Disability: A Job Demands–Resources Perspective

2021

In the contexts where people with intellectual disability work, there are factors that determine their job satisfaction. The objective of this study was to test the adequacy of the central assumptions of the Job Demands–Resources (JD-R) theory in workers with intellectual disability employed in different work alternatives. Data from 362 workers in sheltered workshops and 192 workers in supported employment were utilized. The model was contrasted using a structural equation model and a multi-group analysis. The results supported the suitability of the model and confirmed that job demands and job resources evoke two relatively independent processes such as health impairment and motivational p…