7,718 research outputs found
Elliptic Phases: A Study of the Nonlinear Elasticity of Twist-Grain Boundaries
We develop an explicit and tractable representation of a twist-grain-boundary
phase of a smectic A liquid crystal. This allows us to calculate the
interaction energy between grain boundaries and the relative contributions from
the bending and compression deformations. We discuss the special stability of
the 90 degree grain boundaries and discuss the relation of this structure to
the Schwarz D surface.Comment: 4 pages, 2 figure
Soliton response to transient trap variations
The response of bright and dark solitons to rapid variations in an expulsive
longitudinal trap is investigated. We concentrate on the effect of transient
changes in the trap frequency in the form of temporal delta kicks and the
hyperbolic cotangent functions. Exact expressions are obtained for the soliton
profiles. This is accomplished using the fact that a suitable linear
Schrodinger stationary state solution in time can be effectively combined with
the solutions of non-linear Schrodinger equation, for obtaining solutions of
the Gross-Pitaevskii equation with time dependent scattering length in a
harmonic trap. Interestingly, there is rapid pulse amplification in certain
scenarios
Origin of Middle-Infrared Peaks in Cerium Compounds
We have demonstrated that the middle-infrared (mid-IR) peaks in the optical
conductivity spectra of Ce ( = Pd, Sn, In) can be explained by
first-principle band structure calculation with the spin-orbit interaction. The
mid-IR peak shapes in these materials are not identical to one another:
CePd, CeSn, and CeIn have a triple-peak structure, double-peak
structure and broad single-peak structure, respectively. These peaks can be
theoretically explained by the optical transition from the occupied state to
the spin-orbit splitted Ce state. This result indicates that the mid-IR
peaks originate from the simple band picture with the Ce state near the
Fermi level, not from the conventional cf hybridization gap based on the
periodic Anderson model.Comment: 5 pages, 6 figures. To be published in J. Phys. Soc. Jpn. 78(1)
(2009
Pressure-tuning of the c-f hybridization in Yb metal detected by infrared spectroscopy up to 18 GPa
It has been known that the elemental Yb, a divalent metal at mbient pressure,
becomes a mixed-valent metal under external pressure, with its valence reaching
~2.6 at 30 GPa. In this work, infrared spectroscopy has been used to probe the
evolution of microscopic electronic states associated with the valence
crossover in Yb at external pressures up to 18 GPa. The measured infrared
reflectivity spectrum R(w) of Yb has shown large variations with pressure. In
particular, R(w) develops a deep minimum in the mid-infrared, which shifts to
lower energy with increasing pressure. The dip is attributed to optical
absorption due to a conduction c-f electron hybridization state, similarly to
those previously observed for heavy fermion compounds. The red shift of the dip
indicates that the - hybridization decreases with pressure, which is
consistent with the increase of valence.Comment: 2 pages, to appear in J. Phys. Soc. Jpn. Supp
The Tenerife Cosmic Microwave Background Maps: Observations and First Analysis
The results of the Tenerife Cosmic Microwave Background (CMB) experiments are
presented. These observations cover 5000 and 6500 square degrees on the sky at
10 and 15 GHz respectively centred around Dec.~ +35 degrees. The experiments
are sensitive to multipoles l=10-30 which corresponds to the Sachs-Wolfe
plateau of the CMB power spectra. The sensitivity of the results are ~31 and
\~12 microK at 10 and 15 GHz respectively in a beam-size region (5 degrees
FWHM). The data at 15 GHz show clear detection of structure at high Galactic
latitude; the results at 10 GHz are compatible with these, but at lower
significance. A likelihood analysis of the 10 and 15 GHz data at high Galactic
latitude, assuming a flat CMB band power spectra gives a signal Delta
T_l=30+10-8 microK (68 % C.L.). Including the possible contaminating effect due
to the diffuse Galactic component, the CMB signal is Delta T_l=30+15-11 microK.
These values are highly stable against the Galactic cut chosen. Assuming a
Harrison-Zeldovich spectrum for the primordial fluctuations, the above values
imply an expected quadrupole Q_RMS-PS=20+10-7 microK which confirms previous
results from these experiments, and which are compatible with the COBE DMR.Comment: 17 pages, 7 figures. Submitted to Ap
Effects of mill type (hammer vs roller) and particle size uniformity on growth performance, nutrient digestibility, and stomach morphology in finishing pigs
Two experiments were conducted to determine the effects of mill type and particle size uniformity on finishing pigs. In Exp. 1, 120 pigs, with an average initial weight of 105 lb, were fed corn-soybean meal-based diets for 57 d. The corn was milled so that all diets had an average mean particle size of 800 11m (± 20), yet differed in particle size uniformity (Sgw). To obtain the most uniform treatment (1.9 Sgw), corn was milled through a roller mill. The intermediate treatment (2.3 Sgw) was obtained by milling corn through a hammermill. The least uniform treatment (2.7 Sgw) was obtained by blending coarsely and finely ground corn. Growth performance of pigs was not affected by Sgw of the diet. However, digestibilities of DM, N, and GE increased as Sgw was reduced. In Exp. 2, 128 pigs, widl an average initial weight of 150 lb, were fed diets with corn milled to 450 JLm (± 7) in a hammermill or a roller mill. The hammermilled corn had an Sgw of 1.8 and the rollermilled corn had an Sgw of 2.0. The diets were fed in meal or pelleted form. There were no interactions among mill type and diet form. Digestibilities of DM and N were greater for the hammermilled treatments, but no growth performance differences were due to mill type. Pelleting increased ADG 9% and improved efficiency of gain by 5 %. Pelleting also increased the severity of stomach lesions. In conclusion, at 800 and 450 p.m, mill type did not affect growth performance. However, nutrient digestibilities were improved by decreasing variability in particle size, a response that merits further investigation.; Swine Day, Manhattan, KS, November 19, 199
Application of Hansch’s Model to Capsaicinoids and Capsinoids: A Study Using the Quantitative Structure−Activity Relationship. A Novel Method for the Synthesis of Capsinoids
We describe a synthetic approach for two families of compounds, the capsaicinoids and capsinoids,
as part of a study of the quantitative relationship between structure and activity
Physical Aspects of Axonemal Beating and Swimming
We discuss a two-dimensional model for the dynamics of axonemal deformations
driven by internally generated forces of molecular motors. Our model consists
of an elastic filament pair connected by active elements. We derive the dynamic
equations for this system in presence of internal forces. In the limit of small
deformations, a perturbative approach allows us to calculate filament shapes
and the tension profile. We demonstrate that periodic filament motion can be
generated via a self-organization of elastic filaments and molecular motors.
Oscillatory motion and the propagation of bending waves can occur for an
initially non-moving state via an instability termed Hopf bifurcation. Close to
this instability, the behavior of the system is shown to be independent of
microscopic details of the axoneme and the force-generating mechanism. The
oscillation frequency however does depend on properties of the molecular
motors. We calculate the oscillation frequency at the bifurcation point and
show that a large frequency range is accessible by varying the axonemal length
between 1 and 50m. We calculate the velocity of swimming of a flagellum
and discuss the effects of boundary conditions and externally applied forces on
the axonemal oscillations.Comment: 14 pages, 8 figures, REVTE
Observations of the Cosmic Microwave Background and Implications for Cosmology and Large Scale Structure
Observations of the Cosmic Microwave Background (CMB) are discussed, with
particular emphasis on current ground-based experiments and on future
satellite, balloon and interferometer experiments. Observational techniques and
the effects of contaminating foregrounds are highlighted. Recent CMB data is
used with large scale structure (LSS) data to constrain cosmological parameters
and the complementary nature of CMB, LSS and supernova distance data is
emphasized.Comment: 23 pages, 10 figures. Phil. Trans. R. Soc. Lond. A., 1998, in pres
The Politics of Commerce : The Congress of Chambers of Commerce of the Empire, 1886-1914
Peer reviewedPublisher PD
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