A polynomial algorithm for minimal interval representation

The following problem arises in the context of object representation: given two endpoints of an interval in a Gray code table, find a Boolean function in DNF that represents this interval, with as few prime implicants as possible. This paper shows that there is a unique minimal representation and presents a polynomial algorithm that finds it.     

Scan Statistic Tail Probability Assessment Based on Process Covariance and Window Size

A scan statistic is examined for the purpose of testing the existence of a global peak in a random process with dependent variables of any distribution. The scan statistic tail probability is obtained based on the covariance of the moving sums process, thereby accounting for the spatial nature of the data as well as the size of the searching window. Exact formulas linking this covariance to the window size and the correlation coefficient are developed under general, common and auto covariance structures of the variables in the original process. The implementation and applicability of the formulas are demonstrated on multiple processes of t-statistics, treating also the case of unknown covariance. A sensitivity analysis provides further insight into the variant interaction of the tail probability with the influence parameters. An R code for the tail probability computation and the data analysis is offered within the supplementary material.     

Monitoring and Targeting the Initial Dimerization Stage of Amyloid Self‐Assembly

Amyloid deposits are pathological hallmark of a large group of human degenerative disorders of unrelated etiologies. While accumulating evidence suggests that early oligomers may account for tissue degeneration, most detection tools do not allow the monitoring of early association events. Here we exploit bimolecular fluorescence complementation analysis to detect and quantify the dimerization of three major amyloidogenic polypeptides; islet amyloid polypeptide, β‐amyloid and α‐synuclein. The constructed systems provided direct visualization of protein‐protein interactions in which only assembled dimers display strong fluorescent signal. Potential inhibitors that interfere with the initial intermolecular interactions of islet amyloid polypeptide were further identified using this system. Moreover, the identified compounds were able to inhibit the aggregation and cytotoxicity of islet amyloid polypeptide, demonstrating the importance of targeting amyloid dimer formation for future drug development.     

Identification of the sex pheromone of the lesser date moth, Batrachedra amydraula, using sequential SPME auto-sampling

The identification of the sex pheromone of the lesser date moth, Batrachedra amydraula (Meyrick) was based on GC-MS analysis of volatiles released by virgin females using sequential SPME auto-sampling of headspace and by synthesis of the key component, (4Z,7Z)-4,7-decadien-1-yl acetate. Substantial capture of males in a date palm plantation using a bait consisting of the key component and 5Z-decen-1-yl acetate in a ratio of 1:2 indicated that these are the essential components of the sex pheromone. Addition of 4Z-decen-1-yl acetate and decan-1-yl acetate, which were also identified, did not affect trap-capture. The lesser date moth is the first member of the Batrachedridae whose sex pheromone has been identified. (4Z,7Z)-4,7-Decadien-1-yl acetate is a novel compound among moth sex pheromones.     

Dynamic Nuclear Polarization in the solid state: a transition between the cross effect and the solid effect

Proton Dynamic Nuclear Polarization (DNP) experiments were conducted on a 3.4 T homebuilt hybrid pulsed-EPR-NMR spectrometer, on static samples containing 10 mM or 40 mM TEMPOL in frozen glassy solutions of DMSO/water. During DNP experiments proton-NMR signals are enhanced with the help of microwave (MW) irradiation on or close to the Electron Paramagnetic Resonance (EPR) spectrum of the free radicals in the sample, transferring polarization from the free electrons to the nuclei. In the solid state a distinction is made between three DNP enhancement mechanisms: the Solid Effect (SE), the Cross Effect (CE) and Thermal Mixing (TM). In an effort to determine the dominant DNP mechanisms responsible for the enhancement of the nuclear signals, electron and nuclear spin-lattice relaxation rates, enhancement buildup times and microwave (MW) swept DNP spectra were measured as a function of temperature and MW irradiation strength. We observed lineshape variations of the DNP spectra that indicated changes in the relative contributions of SE-DNP and CE-DNP with temperature and MW power. Using a theoretical model describing the SE-DNP and CE-DNP the DNP spectra could be analyzed without involving the TM-DNP mechanism and the relative SE-DNP and CE-DNP contributions to the nuclear enhancement could be determined. From this analysis it follows that lowering the temperature beyond 20 K increases the SE-DNP and decreases the CE-DNP contributions. Possible explanations for this behavior are suggested.     

Tubular conjugated polymer for chemosensory applications

In this paper, we present the concept of a soluble tubular conjugated polymer (TCP). We report on a fluorescent 5,5'-Bicalixarene-based polymer where the calixarene units are seamlessly incorporated in the conjugated polymeric chain that can respond to a small molecule complexation inside the hydrophobic cavity. In particular, our system demonstrated a reversible rapid fluorescence quenching upon interaction of gaseous nitric oxide with the calixarene moiety.     

Current challenges in compound-specific stable isotope analysis of environmental organic contaminants

Compound-specific stable-isotope analysis (CSIA) has greatly facilitated assessment of sources and transformation processes of organic pollutants. Multielement isotope analysis is one of the most promising applications of CSIA because it even enables distinction of different transformation pathways. This review introduces the essential features of continuous-flow isotope-ratio mass spectrometry (IRMS) and highlights current challenges in environmental analysis as exemplified for the isotopes of nitrogen, hydrogen, chlorine, and oxygen. Strategies and recent advances to enable isotopic measurements of polar contaminants, for example pesticides or pharmaceuticals, are discussed with special emphasis on possible solutions for analysis of low concentrations of contaminants in environmental matrices. Finally, we discuss different levels of calibration and referencing and point out the urgent need for compound-specific isotope standards for gas chromatography-isotope-ratio mass spectrometry (GC-IRMS) of organic pollutants.     

Iron chemistry of an asymmetrically substituted,triazole-functionalised calixarene ligand

The synthesis and characterisation of an asymmetrically substituted calix-triazole ligand are reported. The ligand reacts with the Fe(II) precursor Fe₂Mes₄ to yield an iron(II) calixarene complex that is oxidised by dioxygen to provide a dinuclear Fe(III) compound featuring an oxido bridge.     

Shell model calculations: An efficient new algorithm

We describe an efficient new algorithm which extends the range of feasible shell model calculations. This algorithm is applicable to single shell and multiple shell configurations, where two or more quantum numbers (e.g., L and S) are required to label the states within each shell. The algorithm proceeds by factoring the shell model Hilbert space into a product of subspaces, one for each angular momentum. N-particle wave functions are built up recursively from N – 1 particle wave functions. Three kinds of N – 1- to N-particle coefficients are required to carry out the construction of N-particle electron (or fermion) states from N – 1 particle states. These are (1) coefficients of fractional parentage (CFP s) within a single shell, (2) outerproduct isoscalar factors (OISF s) within a single angular momentum subspace, and (3) innerproduct isoscalar factors (IISF s) which describe how multishell states within the complementary angular momentum subspaces are combined to form totally antisymmetric wave functions. All three types of N – 1- to N-particle coefficients are generated recursively using a single powerful and efficient matrix diagonalization algorithm. Matrix elements of single particle creation and annihilation operators are expressed in terms of single particle CFP s, OISF s, and IISF s. We also describe an efficient algorithm for computing matrix elements of products of creation and anihilation operators by inserting and summing over complete sets of intermediate states. This is the Feynman-like sum over path overlaps procedure. Timing benchmarks are presented comparing the new Drexel University shell model (DUSM ) code with a state of the art shell model code.