Search results for "FLEX"
showing 10 items of 1677 documents
Spiroterpenoids from Hypericum reflexum
1993
Abstract Two new spiroterpenoids, hyperireflexolide A and B, were isolated from Hypericum reflexum . Their structures and stereochemistry were established by spectroscopic methods, including 13 C NMR, DEPT and HMQC, and X-ray data.
Molecular Dynamics of CH
2019
We theoretically investigate graphene layers, proposing them as membranes of subnanometer size suitable for CH4/N2 separation and gas uptake. The observed potential energy surfaces, representing the intermolecular interactions within the CH4/N2 gaseous mixtures and between these and the graphene layers, have been formulated by adopting the so-called Improved Lennard-Jones (ILJ) potential, which is far more accurate than the traditional Lennard-Jones potential. Previously derived ILJ force fields are used to perform extensive molecular dynamics simulations on graphene's ability to separate and adsorb the CH4/N2 mixture. Furthermore, the intramolecular interactions within graphene were explic…
Emotion regulation strategies modulate the effect of adverse childhood experiences on perceived chronic stress with implications for cognitive flexib…
2020
Exposure to early life adversity is associated with chronic stress and a range of stress-related health problems in adulthood. Since chronic stress debilitates activity in the prefrontal cortex (pFC), maladaptive regulatory strategies in response to stress have been proposed as one explanation for the impact of early life adversity on health outcomes in adulthood. We conducted a study to examine the impact of adverse childhood experiences (ACEs) on cognitive flexibility, a key executive function implicated in activity in the pFC, in a sample of adults (N = 486). Additionally, we investigated whether perceptions of chronic stress in adulthood would mediate the influence of ACEs on cognitive …
Towards the quantitative and physically-based interpretation of solar-induced vegetation fluorescence retrieved from global imaging
2021
Due to emerging high spectral resolution, remote sensing techniques and ongoing developments to retrieve the spectrally resolved vegetation fluorescence spectrum from several scales, the light reactions of photosynthesis are receiving a boost of attention for the monitoring of the Earth's carbon balance. Sensor-retrieved vegetation fluorescence (from leaf, tower, airborne or satellite scale) originating from the excited antenna chlorophyll a molecule has become a new quantitative biophysical vegetation parameter retrievable from space using global imaging techniques. However, to retrieve the actual quantum efficiencies, and hence a true photosynthetic status of the observed vegetation, all …
Quantum chemical simulation of excited states of chlorophylls, bacteriochlorophylls and their complexes
2006
The present review describes the use of quantum chemical methods in estimation of structures and electronic transition energies of photosynthetic pigments in vacuum, in solution and imbedded in proteins. Monomeric Mg-porphyrins, chlorophylls and bacteriochlorophylls and their solvent 1:1 and 1:2 complexes were studied. Calculations were performed for Mg-porphyrin, Mg-chlorin, Mg-bacteriochlorin, mesochlorophyll a, chlorophylls a, b, c(1), c(2), c(3), d and bacteriochlorophylls a, b, c, d, e, f, g, h, plus several homologues. Geometries were optimised with PM3, PM3/CISD, PM5, ab initio HF (6-31G*/6-311G**) and density functional B3LYP (6-31G*/6-311G**) methods. Spectroscopic transition energ…
Sun-induced fluorescence - a new probe of photosynthesis: First maps from the imaging spectrometer HyPlant.
2015
Variations in photosynthesis still cause substantial uncertainties in predicting photosynthetic CO2 uptake rates and monitoring plant stress. Changes in actual photosynthesis that are not related to greenness of vegetation are difficult to measure by reflectance based optical remote sensing techniques. Several activities are underway to evaluate the sun-induced fluorescence signal on the ground and on a coarse spatial scale using space-borne imaging spectrometers. Intermediate-scale observations using airborne-based imaging spectroscopy, which are critical to bridge the existing gap between small-scale field studies and global observations, are still insufficient. Here we present the first …
Vascular resistance arm of the baroreflex: methodology and comparison with the cardiac chronotropic arm.
2020
Baroreflex response consists of cardiac chronotropic (effect on heart rate), cardiac inotropic (on contractility), venous (on venous return) and vascular (on vascular resistance) arms. Because of its measurement simplicity, cardiac chronotropic arm is most often analysed. The aim was to introduce a method to assess vascular baroreflex arm, and to characterize its changes during stress. We evaluated the effect of orthostasis and mental arithmetics (MA) in 39 (22 female, median age: 18.7 yrs.) and 36 (21 female, 19.2 yrs.) healthy volunteers, respectively. We recorded systolic and mean blood pressure (SBP and MBP) by volume-clamp method and R-R interval (RR) by ECG. Cardiac output (CO) was re…
Selection of blood pressure signal for baroreflex analysis
2020
This study aims to evaluate the strength of the causal coupling among systolic, mean and diastolic blood pressure (SBP, MBP and DBP) with heart period (RR interval) (evaluating cardiac chronotropic baroreflex arm) and peripheral vascular resistance (PVR) (evaluating vascular resistance baroreflex arm) in frequency domain using partial spectral decomposition method. We recorded beat-to-beat RR, SBP, MBP and DBP and PVR values in 39 volunteers during supine rest and head-up tilt. Our results showed that during supine rest the most dominant causal coupling was from DBP to RR in both low and high frequency bands and significantly decreased during orthostasis. The strength of spectral couplings …
El Mediterráneo: modernidad plural
2000
Es la versión española del texto en francés "La Méditerranée : modernité pluriellel. Introduction". [En: Vidal-Beneyto, José&de Puymège, Gérard (Ed.&Coord.) (2000). La Méditerranée: modernité plurielle. Éditions UNESCO - Publisud].Hay, además, una versión española más larga de este texto en: Blanc Altemir, Antonio (Ed.) (1999). El Mediterráneo : un espacio común para la cooperación, el desarrollo y el diálogo intercultural. Madrid: Foca.
Introduction
2000
Existe una versión española en la revista valenciana "Contrastes" [Contrastes: Revista Cultural, Nº 8, pp. 79-85]. Además, hay una versión más larga también en español publicada en libro "El Mediterráneo: un espacio común para la cooperación, el desarrollo y el diálogo intercultural " [En: Blanc Altemir, Antonio (Ed.) (1999). El Mediterráneo : un espacio común para la cooperación, el desarrollo y el diálogo intercultural. Madrid: Foca.]