Pseudo Affine Research Articles

Affine invariant descriptors using Fourier series

In this paper we use Fourier series (FS) to produce normalized descriptors for shape. These descriptors are invariant under any affine transformation. A motion estimation algorithm using FS capable of estimating general two-dimensional affine motion is also proposed. In the case of parameterized shape we use a pseudo affine arc length to compute FS coefficients.

Pseudo affine Wigner distributions: definition and kernel formulation

We introduce a new set of tools for time-varying spectral analysis: the pseudo affine Wigner distributions. Based on the affine Wigner distributions of J. and P. Bertrand (1992), these new time-scale distributions support efficient online operation at the same computational cost as the continuous wavelet transform. Moreover, they take advantage of the proportional bandwidth smoothing inherent in the sliding structure of their implementation to suppress cumbersome interference components. To formalize their place within the echelon of the affine class of time-scale distributions (TSDs), we introduce and study an alternative set of generators for this class.

Histidine ligand affinity chromatography.

The sorbents with immobilized histidine as a pseudo affinity ligand with a wide specificity is described. The possibilities and relevant chemistries to use both particulate and flat or hollow fiber membranes as support matrices are discussed. The usefulness of such adsorbents for the purification of a wide variety of proteins, with relevant interaction mechanism are described. Practical protocols of sample quality, capacity and scaled up and scaled down operations are discussed. Possibilities of pyrogen removal from high value blood proteins and their simultaneous recovery in the pure form, using histidine immobilized sorbents are described.

Detection and Purification of a Putative Gα O-protein from Sorghum bicolor

Summary Purification of a 40 kDa polypeptide from etiolated Sorghum bicolor mesocotyl that cross reacted with anti-Gα O . serum, was accomplished by chromatography of material released by freeze-thawing of mesocotyl microsomal fraction membranes on Af f i-gel Blue pseudo affinity resin followed by anion exchange hplc. Partial purification of 75 kDa and 29 kDa proteins that cross reacted with anti-Gao serum, and of a 65 kDa polypeptide that cross reacted with anti-GPα O 1 serum was accomplished by the same procedure. Protein microsequencing of the 40 kDa Gα O homologue and a 40.5 kDa protein yielded limited amino acid sequence that was consistent with their assignment as Gα subunits. Affinity labelling studies showed that the 40 kDa protein was labelled with [α 32 P]GTP but that the radiolabel could only be partially displaced with excess unlabelled GTP.

SANS study of deformation and relaxation of a comb-like liquid crystal polymer in the nematic phase

A comb-like liquid crystal polymer is stretched and quenched after a certain time in the nematic phase. The conformation of the deformed chain is determined using small angle neutron scattering (SANS) as a function of the temperature of stretching, the stretching ratio and the duration of the relaxation. The scattering data are well fitted to junction affine and phantom network models. Some data are even well fitted by a totally affine model that we call «pseudo affine» because the only parameter, the stretching ratio, is found to be well below the macroscopic stretching ratio. The latter result, never encountered with amorphous polymers, is attributed to the cooperative effects of the nematic phase. We also note that the form factors of the chain in the underformed sample remain similar in the isotropic, nematic and glassy state; they correspond to a Gaussian chain. The same samples were studied by wide angle X-ray scattering. On one hand, the orientation of the mesogenic groups is found to be parallel or perpendicular to the stretching direction depending on the stretching temperature. This result is discussed as a function of the presence of smectic fluctuations. On the other hand, longer relaxations at constant elongation ratio do not lead to a disorganization of the mesogenic group orientation whereas the polymer chains are partly relaxed

Application of the composite model for the mechanical properties of high density polyethylene

AbstractThe existing models of high density polyethylene (HDPE) fail to tackle effectively the development of mechanical anisotropy on drawing at different temperatures. This paper is concerned with the theoretical interpretation of the anisotropic elastic properties of HDPE by applying the composite model proposed by the authors. The model takes into account the change in orientation and crystallinity on drawing. As far as the orientational changes on drawing are concerned, it is seen that the pseudo affine deformation law tan θ = ϕ(n) · tan θ′ with ϕ(n) = n−3/2 is applicable at −60°C only. It is further found that the two parameter analytical form of ϕ(n) reproduces the correct orientational changes on drawing for the entire temperature range from −60 to 100°C. The agreement of the calculated values of E0 and E90 over the entire temperature range at all drawing ratios is quite satisfactory.

The determination of molecular orientation in uniaxially compressed PMMA by X-ray scattering

A procedure is presented for obtaining full molecular orientation information from wide angle X-ray scattering patterns of deformed non-crystalline polymers. The method is based on the analysis of experimental and calculated scattering patterns into their spherical harmonics. The results obtained for PMMA are compared with values predicted by the pseudo affine and affine deformation schemes.