Harmonic morphisms from the Grassmannians and their non-compact duals

In this paper we give a unified framework for the construction of complex valued harmonic morphisms from the real, complex and quaternionic Grassmannians and their non-compact duals. This gives a positive answer to the corresponding open existence problem in the real and quaternionic cases. Mathematics Subject Classifications (2000): 58E20, 53C43, 53C12The author is a member of EDGE, Research Training Network HPRN-CT-2000-00101     

Temperature dependence of the roton in liquid4He

In new neutron scattering measurements on⁴He at saturated vapour pressure (SVP), we have probed to within 0.0007 K of T_λ from below, revealing a dramatic increase in the damping rate of the momentum fluctuations and a marked softening of the roton frequency, with the changes occurring primarily very close to T_λ and being complete at T_λ. In contrast to 20 bars, the roton at SVP does not, however, go completely soft. Above T_λ, the modes are strongly damped and overlapping whereas at 20 bars they are overdamped (non-propagating).     

SCF and limited CI calculations for assignment of the Auger spectrum and of the satellites in the soft X-ray spectrum of H2O

SCF and limited CI calculations have been performed for a number of excited states of doubly ionized water. The calculations allowed an assignment of both the Auger spectrum and most of the satellites in the soft X-ray spectrum. The assignment for the two highest peaks in the Auger spectrum was ambiguous. SCF calculations of the K emission spectrum of H₂O were also performed. It was found that limited CI calculations were of importance for some states with two open shells in one symmetry. Such effects are caused by large off-diagonal lagrangian multiplies connecting the open shells in the reference configuration.     

Specific cleavage of the glycosidic bond between the carbohydrate and ceramide portions in glycosphingolipids using trifluoroacetolysis

A number of glycosphingolipids have been subjected to trifluoroacetolysis. Heating the glycosphingolipid at 100 degrees C for 48 h in mixtures of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) varying from 1:1 to 1:100 (v/v) resulted in complete cleavage of the glycosidic bond between the carbohydrate and the unsaturated base of the ceramide. The fatty acid(s) linked to the amino group of sphingosine were also released by transamidation. The carbohydrate portion was stable under these conditions due to stabilization of the glycosidic bonds by the electronegative O-trifluoroacetyl groups. The 2-acetamido-2-deoxy-hexose units in the glycosphingolipids were converted into their N-trifluoroacetyl analogues. The N-trifluoroacetyl functions could be removed and the 2-acetamido-2-deoxy-hexoses could be reconstituted by N-acetylation.     

Testing methods for fatigue properties of rubber materials and vibration isolators

The main purpose of this investigation was to find out if laboratory fatigue tests in tension give results which can be useful in predicting the service life of a vibration isolator.Four natural rubber vulcanizates with different curing systems were used in the tests. The fatigue life in cyclic loading was determined in tension on standard tensile specimens (dumb-bells) and in shear on two types of vibration isolators. The results indicate that the information achieved in tension is relevant for estimating the service life of an isolator. Both relaxing and non-relaxing tests in tension were made and the relaxing tests seem to give the best correlation between dumb-bells and isolators. As the relaxing tests are also the least time-consuming they are to be preferred for material testing.     

The first-to-zero-sound transition in non-superfluid liquid 4He

Neutron inelastic scattering from ⁴He at T = 2.3 K shows that for Q ? 2 nm^?1 “sound-wave” excitations propagate with the characteristics of ordinary or first sound while for Q ? 3 nm^?1 they propagate with the characteristics of zero sound.     

Precision branching ratio measurement for the superallowed beta+ emitter 62Ga and isospin-symmetry-breaking corrections in A>or=62 nuclei

A high-precision branching ratio measurement for the superallowed beta+ decay of 62Ga was performed at the Isotope Separator and Accelerator radioactive ion beam facility. Nineteen gamma rays emitted following beta+ decay of 62Ga were identified, establishing the dominant superallowed branching ratio to be (99.861+/-0.011)%. Combined with recent half-life and Q-value measurements, this branching ratio yields a superallowed ft value of 3075.6+/-1.4 s for 62Ga decay. These results demonstrate the feasibility of high-precision superallowed branching ratio measurements in the A>or=62 mass region and provide the first stringent tests of the large isospin-symmetry-breaking effects predicted for these decays.     

On Backward p(x)-Parabolic Equations for Image Enhancement

In this study, we investigate the backward p(x)-parabolic equation as a new methodology to enhance images. We propose a novel iterative regularization procedure for the backward p(x)-parabolic equation based on the nonlinear Landweber method for inverse problems. The proposed scheme can also be extended to the family of iterative regularization methods involving the nonlinear Landweber method. We also investigate the connection between the variable exponent p(x) in the proposed energy functional and the diffusivity function in the corresponding Euler-Lagrange equation. It is well known that the forward problems converges to a constant solution destroying the image. The purpose of the approach of the backward problems is twofold. First, solving the backward problem by a sequence of forward problems, we obtain a smooth image which is denoised. Second, by choosing the initial data properly, we try to reduce the blurriness of the image. The numerical results for denoising appear to give improvement over standard methods as shown by preliminary results.