Search results for "Absolute"

Crystallography of encapsulated molecules.

2017

The crystallography of supramolecular host–guest complexes is reviewed and discussed as a part of small molecule crystallography. In these complexes, the host binds the guests through weak supramolecular interactions, such as hydrogen and halogen bonding, cation–π, anion–π, C–H–π, π–π, C–H–anion interactions and the hydrophobic effect. As the guest often shows severe disorder, large thermal motion and low occupancies, the reliable crystallographic determination of the guest can be very demanding. The analysis of host–guest interactions using tools such as Hirshfeld and cavity volume surface analysis will help to look closely at the most important host–guest interactions. The jewel in the cr…

Norm estimates for operators from Hp to ℓq

AbstractWe give upper and lower estimates of the norm of a bounded linear operator from the Hardy space Hp to ℓq in terms of the norm of the rows and the columns of its associated matrix in certain vector-valued sequence spaces.

Iodine hyperfine structure and absolute frequency measurements at 565, 576, and 585nm

2006

Abstract The hyperfine structure splittings of the P(10)14-1, R(15)14-1, and R(99)15-1 transitions at 585 nm, P(62)17-1 at 576 nm, and P(80)21-1 at 565 nm in 127 I 2 are measured by heterodyne spectroscopy using two dye lasers. In addition, the absolute frequencies of the hyperfine components P(10)14-1 a 15 and P(80)21-1 a 10 are determined using a self-referenced frequency comb. These frequencies are used in an experiment testing relativistic time dilation by laser spectroscopy on a fast ion beam.

Euclidean geometry and physical space

2006

It takes a good deal of historical imagination to picture the kinds of debates that accompanied the slow process, which ultimately led to the acceptance of non-Euclidean geometries little more than a century ago. The difficulty stems mainly from our tendency to think of geometry as a branch of pure mathematics rather than as a science with deep empirical roots, the oldest natural science so to speak. For many of us, there is a natural tendency to think of geometry in idealized, Platonic terms. So to gain a sense of how late nineteenth-century authorities debated over the true geometry of physical space, it may help to remember the etymological roots of geometry: “geo” plus “metria” literall…

Influence of impurity scattering on Drude response in heavy-fermion UPd2Al3

2010

The frequency-dependent conductivity of heavy-fermion metals can often be described within the picture of the Drude response: the transport relaxation rate is the only relevant frequency scale and, furthermore, reduced by orders of magnitude compared to normal metals. While the relaxation-time enhancement corresponds to the effective-mass enhancement in these materials, i.e. a fundamental material characteristic, the absolute value of the relaxation time depends on the details of the relevant scattering processes. Here we discuss the influence of impurity scattering on the Drude response of the heavy fermions in UPd2Al3 by comparing different thin film samples.

Not Race, but Grace: Presbyterian Missionaries and American Indians, 1837-1893

1980

Race, writes George W. Stocking, Jr., was "a characteristically nineteenthcentury phenomenon." Historians of articulate racial thought in America generally believe that the optimism of the eighteenth century gave way in the nineteenth to pessimism in matters of race. Growing numbers of scientists, and perhaps nonscientists too, came to believe that certain races were innately inferior, retarded by inherited qualities that were unchangeable or changeable only over long periods of time, and that cultural manifestations were the product primarily of biological endowment. By late in the century, according to Stocking, "race and culture were linked in a single evolutionary hierarchy extending fr…

Lealtad y unidad en Miguel de Lastarria y Francisco Magariños. Dos proyectos políticos para el Río de la Plata entre la restauración y el trienio lib…

2021

En este trabajo se pretende un abordaje de lo político desde dos experiencias vitales en las que impactaron las revoluciones de independencia durante los años de la restauración y el trienio liberal. Se trata de dos personajes, Miguel de Lastarria y Francisco Magariños, cuyas vivencias en el marco revolucionario del Río de la Plata impactaron sus horizontes de expectativas y configuraron sus identidades a través de unas posiciones de defensa y lealtad a la monarquía hispánica. En ambos casos, la línea que definió sus posicionamientos políticos ante la crisis monárquica fue la de una postura de absoluta fidelidad a la monarquía, pero que se tradujo en proyectos políticos distintos como soluc…

Size Dependent Breakdown of Superconductivity in Ultranarrow Nanowires

2005

Below a certain temperature Tc (typically cryogenic), some materials lose their electric resistance R entering a superconducting state. Folowing the general trend toward a large scale integration of a greater number of electronic components, it is desirable to use superconducting elements in order to minimize heat dissipation. It is expected that the basic property of a superconductor, i.e. dissipationless electric current, will be preserved at reduced scales required by modern nanoelectronics. Unfortunately, there are indications that for a certain critical size limit of the order of 10 nm, below which a "superconducting" wire is no longer a superconductor in a sense that it acquires a fin…

Resolution of β-aminophosphines with chiral cyclopalladated complexes

2005

Abstract Resolution of the racemic chiral β-aminophosphines Ph 2 PCH 2 CH(Ph)NH(Ar) ( L 1 for Ar = C 6 H 5 and L 2 for Ar = 2,6-C 6 H 3 i Pr 2 ) has been investigated by use of different cyclopalladated complexes as chiral agents. The resulting complexes afford diastereomeric adducts in a 1:1 ratio. After successive crystallizations from ethanol, a d.e. of 98% was achieved for one aminophosphine palladium complex, while no significant d.e. was obtained after crystallizations from chlorinated solvents. The X-ray structure analysis has pointed out intermolecular hydrogen interactions N–H⋯Cl between the P,N ligand and the chloride ion, which are responsible for the formation and stabilization …

Skyrmion-number dependence of spin-transfer torque on magnetic bubbles

2015

We theoretically study the skyrmion-number dependence of spin-transfer torque acting on magnetic bubbles. The skymrion number of magnetic bubbles can take any integer value depending on the magnetic profile on its circumference and the size of the bubble. We find that the transverse motion of a bubble with respect to the charge current is greatly suppressed as the absolute value of the skyrmion number departs from unity, whereas the longitudinal motion is less sensitive.