Quasi-implication algebras,Part I: Elementary theory

Quasi-implication algebras (QIA's) are intended to generalize orthomodular lattices (OML's) in the same way that implication algebras (J. C. Abbott) generalize Boolean lattices. A QIA is defined to be a setQ together with a binary operation → satisfying the following conditions (a→b is denotedab). (Q1) $$\left( {ab} \right)a = a$$ (Q2) $$\left( {ab} \right)\left( {ac} \right) = \left( {ba} \right)\left( {bc} \right)$$ (Q3) $$\left( {\left( {ab} \right)\left( {ba} \right)} \right)a = \left( {\left( {ba} \right)\left( {ab} \right)} \right)b$$ Every OML induces a QIA, wherea → b=a ^⊥?(a?b). On the other hand, every QIA induces a join semi-lattice with a greatest element 1, where 1=aa,a≤b iffab=1, anda?b=((ab)(ba))a. A bounded QIA is defined to be a QIA with a least element 0 (w.r.t.≤). The QIA associated with any OML is bounded, the zero elements being the same. Conversely, every bounded QIA induces an OML, wherea ^⊥=a0, anda?b=((ab)(a0))0. The relationC of compatibility is defined so thataCb iffa≤ba, and it is shown that every compatible sub-QIA of a QIA is an implication algebra.     

Tissue self-affinity and polarized light scattering in the born approximation: a new model for precancer detection

Light scattered from biological tissues can exhibit an inverse power law spectral component. We develop a model based on the Born approximation and von Karman (self-affine) spatial correlation of submicron tissue refractive index to account for this. The model is applied to light scattering spectra obtained from excised esophagi of normal and carcinogen-treated rats. Power law exponents used to fit dysplastic tissue site spectra are significantly smaller than those from normal sites, indicating that changes in tissue self-affinity can serve as a potential biomarker for precancer.     

Conformational Analysis of (S)-4,5,6,7-Tetrahydro-5-Methylimidazo [4,5,1-jk][1,4]-Benzodiazepin-2(1H)-one (R78362)

The solution and solid state conformation of (S)-4,5,6,7-tetrahydro-5-methylimidazo [4,5,1-jk][1,4]-benzodiazepin-2(1H)-one (R78362) have been investigated by low temperature NMR and x-ray diffraction studies. The ¹H NMR spectrum of R78362 shows no evidence of the presence of multiple conformers in the temperature range 340K - 177K. Molecular mechanisms and semiempirical molecular orbital calculations suggest that the nitrogen and ring inversion barriers of R78362 are small and thus a time-averaged ¹H NMR spectrum is probably occurring at 298K. The x-ray diffraction data indicated that there were two independent molecules in the asymmetric unit of the crystal. The two molecules had similar conformations with the benzoimidazole ring being planar and the diazepine ring in a “half-chair” conformation.     

Hyperfine interactions of111In→111Cd probe atoms on GaAs (111)B reconstructed surfaces

Hyperfine Interactions - We have used111In→111Cd perturbed-angular-correlation (PAC) spectroscopy to measure hyperfine interactions at surface sites on two molecular-beam-epitaxy-grown GaAs...     

Nanoprobes for intracellular and single cell surface‐enhanced Raman spectroscopy (SERS)

Surface‐enhanced Raman spectroscopy (SERS) is a promising and powerful label free technique for high resolution analysis of single cells. For intracellular analysis, there is a need for SERS‐active nanoprobes that are minimally invasive to cells, do not affect cell viability, and provide reproducible signals. This work reviews the state‐of‐the‐art tools currently available for intracellular SERS. Various types of SERS probes are considered, including colloidal gold and silver nanoparticles, metallized optical fibers, and tip‐enhanced Raman probes. We also discuss recently developed SERS‐active nanopipettes implemented on the basis of pulled glass microcapillaries. Finally, the critical aspects of selecting an optimal SERS nanoprobe for single‐cell analysis depending on a particular application are summarized. Copyright © 2012 John Wiley & Sons, Ltd.     

Hadamard-encoded sub-slice fMRI for reduced signal dropout

T2?-weighted blood oxygen level-dependent functional magnetic resonance imaging is adversely affected by susceptibility-induced field gradients in brain regions adjoining air interfaces that cause image distortion and signal dropout. Reducing slice thickness diminishes signal dropout but is accompanied by reduced signal-to-noise ratio (SNR). This study proposes simultaneous excitation of subslices with total width equal to the desired slice thickness, employing alternating Hadamard-encoded radiofrequency pulses coupled with incoherent addition of the subslices to achieve reduction of through-plane dephasing with minimal SNR loss but at the expense of a reduction in temporal resolution. Using a sensory task and hypercapnic challenge with breathholding (BH), results with two subslices per slice and a twofold reduction in temporal resolution show improved activation relative to a conventional acquisition. Average (eight subjects) T-scores in the BH task increased by 16% (P<.0003), and activation extent increased by 12% (not significant). In frontal brain regions, significant improvements in BH activation extent (11.4%, P<.05) and T-scores (18%, P<.0002) were demonstrated. Higher temporal resolution can be achieved by tradeoff of SNR.     

细胞内蛋白质磁共振

细胞内的环境异常复杂,其中生物大分子的浓度超过300 mg/mL并占据着大约30%的细胞内空间. 然而,直到目前为止大多数的蛋白质研究仍然在细胞外或是甚至非常稀的缓冲液中进行. 细胞内磁共振（In-cell NMR）提供了一个可以直接非损伤地获取细胞内原子水平信息的方法. 虽然In-cell NMR在近10年里有了较大的发展,但是这一技术尚未成熟. 在该篇综述中,作者首先总结制约这一技术发展的因素以及研究中需要注意的事项,最后讨论了未来的发展方向.     

The semidirect products of finite cyclic groups that areI-E groups

AnI-E group is a group in which the endomorphism near-ring generated by the group's inner automorphisms equals the endomorphism near-ring generated by its endomorphisms. In this paper we shall completely determine the finite groups that are semidirect products of cyclic groups and areI-E groups.     

A Mössbauer spectral study of the Jilin meteorite

The iron57 Mössbauer spectra of three different samples of the Jilin meteorite have been measured at 78 and 295 K. Five iron containing major components are identified, two magnetic components, kamacite and troilite, and three nonmagnetic components, olivine, pyroxene, and an iron(III) component. The relative absorption areas of these five components show that sample A contains a larger fraction of magnetic components, ca. 50 percent, than samples B and C, which contain ca. 30 percent. This difference indicates a significant compositional inhomogeneity in the Jilin meteorite. The fit of the troilite component sextet is extensively discussed in the paper and requires the adjustment of not only the isomer shift and hyperfine field, but also of the quadrupole interaction, the asymmetry parameter of the electric field gradient tensor, and the orientation of the hyperfine field in the principal axes of the electric field gradient tensor. The smaller isomer shift and hyperfine field of the kamacite mineral in sample B indicate that this sample contains less nickel than the kamacite in samples A and C, in which the amount of nickel is estimated to be ca. 9 percent. On the basis of its hyperfine parameters, the iron(III) component is assigned to iron(III) substituted on the M1 site of pyroxene.