Quantitative problems in using nuclear reactions and dielectric detectors for the detection of stable isotopes (6Li and10B) in biological samples

The methodology of the detection of (n, ) nuclear reactions by means of cellulose nitrate detectors is discussed with special reference to the reliability of the quantitative estimates. The discrimination of¹⁰B and⁶Li from the other isotopes is possible by using thin coloured detectors. The ratio of the number of tracks found at the level of a¹⁰B or⁵Li-enriched calibrating sample, and the number expected from theoretical calculation, i.e. the detection efficiency, P is generally below 1. P is fairly sensitive to the experimental conditions, and for precise quantitative measurements it must be determined separately for each different experiment. The gelatin, used for solidification of liquid samples is boron contaminated (almost 1 mol natural B per g). It has been observed, especially with¹⁰B-enriched liquid samples, that part of the stable tracer under study is lost during sample preparation.⁶Li extra tracks appear at the rear face of thick, non-plastic-supported detectors. Boron diffuses in the cellulose-nitrate detectors with the diffusion coefficient of the order of 10^–8 cm²·s^–1. Therefore it requires rapid operations for microlocation of boron with high resolving power.     

A study of the self-injected laser for subnanosecond pulse generation

We present a detailed analysis of the self-injected Nd:YAG laser which is capable of generating subnanosecond duration pulses with peak powers as high as 200 MW. The model predicts that pulses with durations much shorter than the electrical rise time of the electrooptical switch driver can be obtained. Application of this technique to a conventionally Q-switched Nd:YAG laser allowed us to obtain 550 ps pulses with 120 mJ in a very stable and reliable way.     

Intercellular communication: the Drosophila innexin multiprotein family of gap junction proteins

Gap junctions belong to the most conserved cellular structures in multicellular organisms, from Hydra to man. They contain tightly packed clusters of hydrophilic membrane channels connecting the cytoplasms of adjacent cells, thus allowing direct communication of cells and tissues through the diffusion of ions, metabolites, and cyclic nucleotides. Recent evidence suggests that gap junctions are constructed by three different families of four transmembrane proteins: the Connexins and the Innexins found in vertebrates and in invertebrates, respectively, and the Innexin-like Pannexins, which were recently discovered in humans. This article focuses on the Drosophila Innexin multiprotein family, which is comprised of eight members. We highlight common structural features and discuss recent findings that suggest close similarities in cellular distribution, function, and regulation of Drosophila Innexins and vertebrate gap junction proteins.     

Enhancing the violation of the einstein-podolsky-rosen local realism by quantum hyperentanglement

Mermin's observation [Phys. Rev. Lett. 65, 1838 (1990)] that the magnitude of the violation of local realism, defined as the ratio between the quantum prediction and the classical bound, can grow exponentially with the size of the system is demonstrated using two-photon hyperentangled states entangled in polarization and path degrees of freedom, and local measurements of polarization and path simultaneously.     

Uniqueness of completions and related topics

A bounded subset of a normed linear space is said to be (diametrically) complete if it cannot be enlarged without increasing the diameter. A complete super set of a bounded set K having the same diameter as K is called a completion of K. In general, a bounded set may have different completions. We study normed linear spaces having the property that there exists a nontrivial segment with a unique completion. It turns out that this property is strictly weaker than the property that each complete set is a ball, and it is strictly stronger than the property that each set of constant width is a ball. Extensions of this property are also discussed.