Modal theory for the two-frequency mutual coherence function in random media: beam waves

Pulse propagation in a random medium is mainly determined by the two-frequency mutual coherence function which satisfies the parabolic equation. It has recently been shown that this equation can be solved by separation of variables, thereby reducing the solution for any structure function to the solution of ordinary differential equations. In this paper, the method is applied for a beam-wave excitation in a random medium. The exact solution for a quadratic medium is derived. For non-quadratic power-law media an analytical expression at equal positions is presented.     

Synthesis of 1,3-dihydro-2H-benzimidazol-2-one from 2-aminobenzamide

A method for the synthesis of 2-henzimidazolone ( 1 ) has been devised which does not depend on 1,2-diaminobenzene ( 2 ) as a starting material. This method produces 1 in good yield by the reaction of hypohalite with 2′-carbamoylphthalanilic acid ( 7 ), a compound readily prepared by the reaction of 2-aminobenzamide ( 3 ) and phthalic anhydride. Contrary to prior indications 1 can be hydrolyzed in the presence of acid at temperatures greater than 200 giving excellent yields of 2.     

Masses of S and P wave mesons and pseudoscalar decay constants using a confinement scheme

In the framework of relativistic harmonic confinement model for quarks and antiquarks, the masses of S- and P-wave mesons and pseudoscalar decay constants from light flavour to heavy flavour sectors are computed. The residual two-body Coulomb interaction and the spin-dependent interaction of the confined one gluon exchange effects (COGEP) such as spin-spin and spin-orbit interactions are perturbatively incorporated with the confinement energy to get the respective vector-pseudoscalar meson mass differences. Here we employ the same parametrization and model parameters as used in a recent study of low-lying hadron masses and leptonic decay widths. The results are being compared with the values obtained from other theoretical models and the experimental values.     

Few-cycle THz spectroscopy of nanostructures

Optically excited plasma oscillations in n-doped GaAs epilayers emit intense THz pulses. Using a THz-pump and THz-probe technique we observe the response of the intersubband polarization in semiconductor quantum structures. THz Cross-correlation measurements of modulation doped semiconductor quantum structures allow to determine the absorption, the dispersion, and the dephasing times of the quantized electrons.     

Site-Selective Artificial Ribonucleases: Renaissance of Oligonucleotide Conjugates for Irreversible Cleavage of RNA Sequences

RNA-targeting therapeutics require highly efficient sequence-specific devices capable of RNA irreversible degradation in vivo. The most developed methods of sequence-specific RNA cleavage, such as siRNA or antisense oligonucleotides (ASO), are currently based on recruitment of either intracellular multi-protein complexes or enzymes, leaving alternative approaches (e.g., ribozymes and DNAzymes) far behind. Recently, site-selective artificial ribonucleases combining the oligonucleotide recognition motifs (or their structural analogues) and catalytically active groups in a single molecular scaffold have been proven to be a great competitor to siRNA and ASO. Using the most efficient catalytic groups, utilising both metal ion-dependent (Cu(II)-2,9-dimethylphenanthroline) and metal ion-free (Tris(2-aminobenzimidazole)) on the one hand and PNA as an RNA recognising oligonucleotide on the other, allowed site-selective artificial RNases to be created with half-lives of 0.5–1 h. Artificial RNases based on the catalytic peptide [(ArgLeu)₂Gly]₂ were able to take progress a step further by demonstrating an ability to cleave miRNA-21 in tumour cells and provide a significant reduction of tumour growth in mice.     

Leaning towers

Masonry, as a unilateral material, can resist compressive stresses but has feeble tensile strength. A masonry wall or tower, subjected to uneven foundation settlements, will crack, and these cracks may lead to overall structural collapse. Of particular interest is the leaning tower, in which a fissure (of a shape to be determined) develops progressively up to the point of critical stability. A practical rule is developed for the maximum inclination that may be regarded as safe for a masonry tower.

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Sommario La muratura, materiale a comportamento unilaterale, puo' sopportare sforzi di compressione ma ha una modesta resistenza a trazione. Una parete od una torre in muratura, soggette a cedimenti fondali, si fessurano e tali lesioni possono condurre al collasso globale. Un caso di particolare interesse e' quello di una torre inclinata nella quale una lesione (la cui forma e' da determinare) si sviluppa progressivamente fino al punto di stabilita' critica. Nel presente studio si sviluppa un criterio pratico di sicurezza per la massima inclinazione ammissibile per una torre in muratura.