First-order symmetry of weak-field partial thermoremanence in multi-domain ferromagnetic grains. 1. Experimental evidence and physical implications

2006 ◽  
Vol 245 (1-2) ◽  
pp. 438-453 ◽  
Author(s):  
A BIGGIN ◽  
T POIDRAS
Keyword(s):  
Experimental Evidence ◽  
Weak Field ◽  
First Order

The kinetics of isomerization of allylbenzene homogeneously catalysed by palladium(II) in acetic acid

1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Active Catalyst ◽  
Bimolecular Reaction ◽  
Equilibrium System ◽  
Constant Concentration ◽  
First Order ◽  
Rate Determining Step ◽  
Kinetics Of

The changes in the kinetics observed during the isomerization of allylbenzene catalysed by palladium(II) are interpreted in terms of the slow formation of a hydrido complex of palladium(II) which subsequently attains a constant concentration in an equilibrium system. The kinetics during these phases are shown to be consistent with first-order dependence on the concentration of an active catalyst formed in a bimolecular reaction from a mononuclear palladium(II) complex and with a regenerative hydrido-π-alkene-σ-alkyl mechanism of isomerization. The hypothesis that a further stage in the kinetics reflects a change in the rate determining step to one involving alkene displacement from the catalyst is supported by the experimental evidence. The concentration of active catalyst is shown not to fall appreciably until all the allylbenzene has undergone isomerization, but thereafter there is a slow reduction of catalytic activity which is not completely restored by the addition of further allylbenzene. It is suggested that the slow formation of a π-allylic complex is responsible.

Finite nuclear fragmenting systems: An experimental evidence of a first order liquid gas phase transition

2001 ◽  
Author(s):  
M. D'AGOSTINO ◽  
F. GULMINELLI ◽  
PH. CHOMAZ ◽  
M. BRUNO ◽  
F. CANNATA ◽  
...  
Keyword(s):  
Phase Transition ◽  
Experimental Evidence ◽  
Gas Phase ◽  
First Order

Rhodium(I) catalyzed E/Z isomerization of dimethyl butenedioate

1985 ◽  
Vol 50 (6) ◽  
pp. 1274-1282 ◽  
Author(s):  
Jaroslav Podlaha ◽  
Miloš Procházka
Keyword(s):  
Experimental Evidence ◽  
Triphenylphosphine Oxide ◽  
Active Species ◽  
Equimolar Mixture ◽  
Rhodium Complexes ◽  
Hydride Complexes ◽  
High Substrate ◽  
First Order ◽  
Highly Effective ◽  
Catalytically Active

Hydride complexes of Rh(I) represent highly effective homogeneous catalysts of the isomerization of (Z)-dimethyl butenedioate (I) yielding (E)-dimethyl butenedioate (II) in benzene at 25 °C. The reaction catalyzed by RhH(P(C6H5)3)4 is first order both in I and in the catalyst, k = 0.51 l mol-1 s-1, Ea = 48 kJ mol-1, ΔS≠ = -46 J mol-1 K-1. At high substrate-to-catalyst ratios the catalyst is inactivated, which consists mainly in deoxygenation and decarbonylation of the E- and Z-esters with formation of methyl 2-butenoate, triphenylphosphine oxide, and carbonylocomplexes of Rh(I). Statistical redistribution of deuterium during the isomerization of equimolar mixture of I and [2,3-2H2]-I and other experimental evidence are consistent with the addition-elimination hydride mechanism of the isomerization involving σ-alkyl rhodium complexes as the intermediates and RhH(P(C6H5)3)2 as the catalytically active species.

scholarly journals COMMENTS ON HIGHER-SPIN SYMMETRIES

2009 ◽  
Vol 06 (02) ◽  
pp. 285-342 ◽  
Author(s):  
XAVIER BEKAERT
Keyword(s):  
Lie Algebra ◽  
Differential Operators ◽  
Symmetric Tensor ◽  
Weak Field ◽  
Gauge Fields ◽  
Gauge Parameter ◽  
Gauge Transformations ◽  
First Order ◽  
Gauge Symmetries ◽  
Higher Spin

The unconstrained frame-like formulation of an infinite tower of completely symmetric tensor gauge fields is reviewed and examined in the limit where the cosmological constant goes to zero. By partially fixing the gauge and solving the torsion constraints, the form of the gauge transformations in the unconstrained metric-like formulation are obtained till first order in a weak field expansion. The algebra of the corresponding gauge symmetries is shown to be equivalent, at this order and modulo (unphysical) gauge parameter redefinitions, to the Lie algebra of Hermitian differential operators on ℝn, the restriction of which to the spin-two sector is the Lie algebra of infinitesimal diffeomorphisms.

scholarly journals Experimental evidence of structural representation of hands in early infancy

2018 ◽  
Vol 43 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Rachel Jubran ◽  
Hannah White ◽  
Alyson Chroust ◽  
Alison Heck ◽  
Ramesh S. Bhatt
Keyword(s):  
Experimental Evidence ◽  
Social Communication ◽  
Haptic Perception ◽  
Early Infancy ◽  
Order Structure ◽  
Structural Representation ◽  
Novelty Preference ◽  
First Order ◽  
Major Organ ◽  
Preference Task

Hands convey important social information, such as an individual’s emotions, goals, and desires, are used to direct attention through pointing, and are a major organ for haptic perception. However, very little is known about infants’ representation of human hands. In Experiment 1, infants tested in a familiarization/novelty preference task discriminated between images of intact hands and images that contained first-order structure distortions (i.e., with locations of fingers altered to result in an unnatural configuration). In Experiment 2, infants tested in a spontaneous preference task exhibited a preference for scrambled hand images over intact images, indicating that 3.5-month-olds have gained sufficient sensitivity to the configural properties of hands to discriminate between intact versus scrambled images without any training in the laboratory. In both procedures, infants’ performance was disrupted by the inversion of images, suggesting that infants’ performance in upright conditions was not based on low-level features. These results indicate that sensitivity to the structure of hands develops early in life. This may lay the foundation for the development of the functional use of hand information for social communication.

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