Search results for "ASYM"

ChemInform Abstract: N1-Functionalized Indole-Phosphane Oxazoline (IndPHOX) Ligands in Asymmetric Allylic Substitution Reactions.

2012

N-Functionalized IndPHOX ligands bearing various groups have been synthesized and the effects of the N1-substituent on the reaction rate, yield, and asymmetric induction in a palladium-catalyzed allylic substitution reaction are reported. The presence of an oxygen atom in the ligands, namely an N-MOM or N-THP group, led to enhancement of the enantioselectivity in the allylic amination reaction. In addition, a ligand with a chiral oxazoline ring at C-1 and a phosphane substituent at C-2 provided high enantioselectivity in good yield in an asymmetric allylic alkylation reaction.

N‐Heterocyclic Carbene Catalyzed Asymmetric Synthesis of Pentacyclic Spirooxindoles via [3+3] Annulations of Isatin‐Derived Enals and Cyclic N‐Sulfon…

2019

Impact of non-idealities on the conductance characteristics of superconductor-insulator-normal metal-insulator-superconductor tunnel junctions

2012

We have investigated the effect of asymmetry in tunnelling resistance of individual normal metal-insulator-superconductor (NIS) tunnel junctions that constitute a SINIS pair, both experimentally and theoretically. Ours results clearly demonstrate that any finite asymmetry in the tunnelling resistance gives rise to an excess current, as compared to its symmetric counterpart, both below and around the gap edge. The signature of this excess current is visible almost up to the critical temperature. We find that this apparent broadening of the density of states is purely electrical in origin. Our calculations also show that any finite resistance that is in series with the tunnelling resistance, …

Inflection points and topology of surfaces in 4-space

2000

We consider asymptotic line fields on generic surfaces in 4-space and show that they are globally defined on locally convex surfaces, and their singularities are the inflection points of the surface. As a consequence of the generalized Poincare-Hopf formula, we obtain some relations between the number of inflection points in a generic surface and its Euler number. In particular, it follows that any 2-sphere, generically embedded as a locally convex surface in 4-space, has at least 4 inflection points.

ASYMPTOTIC CURVES ON SURFACES IN ℝ5

2008

We study asymptotic curves on generically immersed surfaces in ℝ5. We characterize asymptotic directions via the contact of the surface with flat objects (k-planes, k = 1 - 4), give the equation of the asymptotic curves in terms of the coefficients of the second fundamental form and study their generic local configurations.

MUSIC-characterization of small scatterers for normal measurement data

2009

We investigate the reconstruction of the positions of a collection of small metallic objects buried beneath the ground from measurements of the vertical component of scattered fields corresponding to vertically polarized dipole excitations on a horizontal two-dimensional measurement device above the surface of the ground. A MUSIC reconstruction method for this problem has recently been proposed by Iakovleva et al (2007 IEEE Trans. Antennas Propag. 55 2598). In this paper, we give a rigorous theoretical justification of this method. To that end we prove a characterization of the positions of the scatterers in terms of the measurement data, applying an asymptotic analysis of the scattered fie…

Tumor fibroso localizado de la pleura: hallazgos radiológicos

2007

Localized fibrous tumors of the pleura are rare tumors that represent less than 5% of the pleural tumors, although they have also been described in extrathoracic locations such as the abdomen, head and neck or central nervous system. A total of 80% begin in the visceral pleura and are not related with environmental risk factors. They generally occur in patients over 50 with a mild predominance in the woman. Up to 50% of the patients are asymptomatic, so that it appears as an incidental finding on the chest X-ray. These are slow growing tumors. They are seen on the X-ray as well-defined rounded lesions dependent on the pleura and 50% are pediculated. It is important to know its radiological …

Assessment of autonomic function as marker of training status: the role of heart rate recovery after exercise

2014

Heart rate recovery (HRR) is the rate at which the heart rate returns to baseline after a period of exercise. HRR is a marker of autonomic function and a predictor of cardiovascular fitness in healthy subjects and in those with cardiovascular diseases. Moreover, HRR has been proposed as a marker of training status in athletes. Our aim was to perform a review of studies that evaluated HRR after exercise in trained and untrained healthy subjects and assessed its relationship with training status. Several studies suggest that the assessing of HRR after exercise may be useful to distinguish trained from untrained individuals and to establish an athlete’s state of training. However, standardizat…

A muscarinic mechanism inhibiting the release of noradrenaline from peripheral adrenergic nerve fibres by nicotinic agents.

1968

A measurement of the antineutrino asymmetry B in free neutron decay

2005

Abstract We have measured the antineutrino asymmetry B in neutron beta decay, i.e., the correlation of the neutron spin and the antineutrino momentum, with a new method. Our result is B = 0.967 ± 0.006 stat ± 0.010 syst = 0.967 ± 0.012 . Statistical and systematic uncertainty can be considerably reduced in future experiments.