Linear Dynamical Identification: An Integral Transform seen as a Complex Wavelet Transform

This paper presents a technique that allows the direct linearidentification of frequency response functions from the computation ofa weighted integral transform. This transform allows toemphasize the influence of the poles and zeros of the frequencyresponse functions its formation is based on the Cauchy--Weierstrass theorem. It isthen shown that this transform is directly linked to a complex wavelettransform. This representation with a wavelet transform provides abetter understanding of the amplification effects of the weightedintegral transform and allows the singularities analysis.     

The vacuum ultraviolet absorption spectrum of diatomic calcium

Calcium granules (99.5%) have been heated to 615°C in a tantalum furnace and the absorption spectrum has been observed on the SA 61 beam line of SUFERACO (Orsay) using a 3-metre Balzers monochromator down to the -LiF cut-off (1015 Å). An intense Rydberg series has been observed between 1900 and 1500 Å. This series extends from n = 5 to n = 12 and gives the ionization potential at 63068 cm^?1 (1585.6 Å) or 7.819eV and the quantum defect δ = 1.73.     

Interfacial Activity of the Diprotonated 222 Cryptand at the Water/"Oil" Interface Revealed by Molecular Dynamics Simulations

Abstract

Orange II (I) is easily soluble in H₂O. It requires several months for the formation of needle-like crystals from a 0.16 M (saturated) aqueous solution. But when 0.03 M γ-cyclodextrin (γ-CD) is added to an equivalent of (I) at RT, the solution exhibits enhancement of the viscosity in an hour, and the microscopic viewing indicates the formation of a pine needle-like aggregate. Enough old millet jelly-like one shows well arranged stripe pattern upon rubbing. In the induced c.d. spectrum, the π→π* band of this complex appears at ～500 nm in the solution state, but in the aggregate state, it changes to the J-band due to the head-to-tail stacking of (I) and the H-band due to parallel stacking. When MeOH is poured onto the aggregate, the latter changes colour from orange to silver-gray, but keeps the same shape. The driving force for the aggregate formation may be 1. van der Walls contact between γ-CD and two molecules of (I),

2. π-π interaction between the two molecules of (I) in γ-CD,

3. H-bonding and stacking effects between γ-CD.

In this chiral aggregate, γ-CD works as an adhesive for the azo dye.     

The TeV-scale cosmic ray proton and helium spectra: Contributions from the local sources

Recent measurements of cosmic ray proton and helium spectra show a hardening above a few hundreds of GeV. This excess is hard to understand in the framework of the conventional models of galactic cosmic ray production and propagation. Here, we propose to explain this anomaly by the presence of local sources. Cosmic ray propagation is described as a diffusion process taking place inside a two-zone magnetic halo. We calculate the proton and helium fluxes at the Earth between 50 GeV and 100 TeV. Improving over a similar analysis, we consistently derive these fluxes by taking into account both local and remote sources for which a unique injection rate is assumed. We find cosmic ray propagation parameters for which the proton and helium spectra remarkably agree with the PAMELA and CREAM measurements over four decades in energy.     

SOME EXPERIMENTS WITH STABILITY ANALYSIS OF DISCRETE INCOMPRESSIBLE FLOWS IN THE LID-DRIVEN CAVITY

We present results of a stability analysis of the lid-driven cavity flow based on classical C⁰ finite element discretizations of the Navier–Stokes system. Using arc length continuation and subspace iteration to compute the eigenvalues of the tangent operator, we study the dependence of the bifurcation diagram and of the spectrum on the chosen discretization. © 1997 by John Wiley & Sons, Ltd.     

SPECTRA OF FLUORESCENCE LIFETIME AND INTENSITY OF Rhodopseudomonas sphaeroides AT ROOM AND LOW TEMPERATURE. COMPARISON BETWEEN THE WILD TYPE, THE C 71 REACTION CENTER-LESS MUTANT AND THE B800–850 PIGMENT-PROTEIN COMPLEX

Abstract— Spectra of the fluorescence lifetime and intensity of chromatophores from the wild type Rhodopseudomonas sphaeroides , from the C 71 reaction center-less mutant and of the B800–850 light harvesting pigment-protein complex have been studied by phase fluorimetry techniques at different light modulation frequencies at room and low temperature.
As already known, closed reaction centers (saturating light) are still quenchers of antenna fluorescence although with a lower efficiency than when they are opened. The fluorescence yields and lifetimes of both the C 71 mutant strain and the B800–850complex are found to increase by about 30% between room and low temperature.
The fluorescence lifetimes obtained for the C 71 strain (0.65 ns at 20C; 0.85 ns at 77 K) and for the B850 complex (1 ns at 20C; 1.3 ns at 77 K) indicate that the non-radiative deactivation pathways, in the antenna, remain important in the absence of the reaction centers even at low temperature. We suggest that these data arise from the presence of special antenna molecules which act as intrinsic quenchers of the B875 antenna fluorescence. Between room and low temperature, the fluorescence yield and lifetime of the wild type are found roughly constant. This result suggests that the energy trapping by the reaction centers is independent of the temperature. The mechanism governing the energy transfer from the antenna to the reaction centers may differ from the mechanism leading to the energy transfer within the antenna. We suggest that a partially irreversible trapping of the excitation energy, on its way to the reaction center, takes place in the vicinity of the reaction center.     

Self-assembly of an Octa-uranate Cage Complex with a Rigid bis-Catechol Ligand

While the terminally protected tripeptide Boc-Phe-Gly-m-ABA-OMe I (m-ABA, meta-amino benzoic acid) is an excellent gelator of aromatic organic solvents, another similar tripeptide Boc-Leu-Gly-m-ABA-OMe II, where the Phe residue of peptide I is replaced by Leu, cannot form gels with the same solvents. The morphology of the gels of peptide I, characterised by the field-emission scanning electron microscopy and high-resolution transmission electron microscopy, reveals the formation of nanofibrous networks which are known to encapsulate solvent molecules to form gels. The wide-angle X-ray scattering studies of the gels suggest the β-sheet-mediated self-assembly of peptide I in the formation of a nanofibrous network, where π-stacking interactions of Phe play an important role in the self-assembly and gel formation. The dried gel of peptide I observed between crossed polarisers after binding with a physiological dye, Congo red, shows a bluish-green birefringence, a characteristic of amyloid fibrils.     

Prioritization of high throughput screening data of compound mixtures using molecular similarity

This work addresses the problem of enriching high throughput screening (HTS) data of mixtures of five compounds/well without any redundancies and where no structural information of the drug target is available. Devising a mathematical model for mixtures of compounds is extremely difficult. Instead, we employed extended-connectivity fingerprints (ECFPs), which are a new class of fingerprints for molecular characterization. We calculated the Tanimoto similarity between all the compounds which appeared in the active mixtures and ranked them in order of decreasing similarity. This methodology enriched the data in three recent in-house HTS campaigns that were conducted in five compounds/well mixtures. The top 10% most similar compounds captured between 29% and 41% of the active compounds. Although this methodology is not particularly sensitive, considering the quality of the data (ca. 80% noise presumed to be inactive) and the simplicity of the method, we find it useful. It offers a true opportunity to quickly prioritize and enrich primary screening data from mixtures of compounds and therefore reduce the time and the high costs of the secondary screening.