A generalization of cyclic difference sets I

This is the first of two papers on addition sets. In this paper, the basic properties of addition sets are given. It also contains examples of addition sets arising from natural central groupoids, (0, 1)-matrices satisfying the equation M² = dI+λJ and Nth power residues. Their relationship with difference sets is also explained.     

Field characterization of therapeutic ultrasound phased arrays through forward and backward planar projection

Spatial planar projection techniques propagate field measurements from a single plane in front of a transmitter to arbitrary new planes closer to or further away from the source. A linear wave vector frequency-domain projection algorithm is applied to the acoustic fields measured from several focused transducer arrays designed for ultrasound therapy. A polyvinylidene difluoride hydrophone is first scanned in a water tank over a plane using a three-dimensional positioning system to measure the complex pressure field as a function of position. The field is then projected to a series of new planes using the algorithm. Results of the projected fields are compared with direct measurements taken at corresponding distances. Excellent correlation is found between the projected and measured data. The method is shown to be accurate for use with phase-controlled field patterns, providing a rapid and accurate method for obtaining field information over a large spatial volume. This method can significantly simplify the characterization procedure required for phased-array application used for therapy. Most significantly, the wavefront propagated back to a phased array can be used to predict the field produced by different phase and amplitude settings of the array elements. A field back-projected to the source could be used as an improved source function in acoustic modeling.     

Observation of the ABC effect and final-state isospin

Despite the number of inclusive measurements of the pionic fusion reactions, the nature of the ABC effect discovered in 1960 was not completely established. Exclusive measurements of the doublepion-production reactions leading to either fused d, ³He and ⁴He nuclear final states or pp pairs are analyzed. A significant ABC effect—enhancement in the region of low ππ mass—is found only in the isoscalar ππ channel while in the isovector channels it is small or absent. For the reaction with isovector pp final state an ABC effect was not observed even at the special kinematic conditions to reproduce a quasi-bound two-proton state. The total cross sections for the d and 4He fusion reactions show similar resonance-like energy dependence.     

Sliding window proper orthogonal decomposition: Application to linear and nonlinear modal identification

The Proper Orthogonal Decomposition (POD) method is a tool well adapted to analyze vector signals whereas Continuous Gabor Transform (CGT) is suitable for scalar signal with multi-frequency components. In this paper, a method named Sliding Window Proper Orthogonal Decomposition (SWPOD) combining POD and CGT to analyze Multi-Degrees-Of-Freedom (MDOF) vibration system responses is presented. SWPOD gives access to the evolution of the coherent spacial structures and their frequency components versus time. The method is of principal interest in the case of swept-sine excitation of linear or nonlinear systems to access the resonance frequencies, mode shapes and modal damping ratios. A procedure is proposed to extract the linear and nonlinear normal modes of weakly damped MDOF mechanical systems and illustrated using numerical examples.     

Synthesis of Benzo[c]thiophene Analogs Containing Benzimidazole,Benzothiazole, and Oxazole

Iodine-mediated cyclization of benzo[c]thiophene aldehyde with 1,2-diphenylamine/2-aminophenylthiol led to the formation of benzimidazole/benzothiazole-incorporated benzo[c]thiophenes. Similarly, reaction of benzo[c]thiophene aldehyde with p-toluenesulfonylmethyl isocyanide (TOSMIC) reagent in the presence of K₂CO₃ as a base furnished oxazole-containing benzo[c]thiophene analogs.     

Age-Related Carbonylation of Fibrocartilage Structural Proteins Drives Tissue Degenerative Modification

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Exclusive measurement of the pp → nnπ+π+ reaction at 1.1 GeV

First exclusive data for the $\ensuremath{pp \to nn\pi^+\pi^+}$ reaction have been obtained at CELSIUS with the WASA detector setup at a beam energy of T_p = 1.1 GeV. Total and differential cross-sections disagree with theoretical calculations, which predict the $ \Delta$ $ \Delta$ excitation to be the dominant process at this beam energy. Instead, the data require the excitation of one of the nucleons to a higher-lying $ \Delta$ state, preferably the $\ensuremath{\Delta(1600)P_{33}}$ , to be the leading process.     

Expanding the Toolbox for Bicelle-Forming Surfactant–Lipid Mixtures

Bicelles are disk-shaped models of cellular membranes used to study lipid–protein interactions, as well as for structural and functional studies on transmembrane proteins. One challenge for the incorporation of transmembrane proteins in bicelles is the limited range of detergent and lipid combinations available for the successful reconstitution of proteins in model membranes. This is important, as the function and stability of transmembrane proteins are very closely linked to the detergents used for their purification and to the lipids that the proteins are embedded in. Here, we expand the toolkit of lipid and detergent combinations that allow the formation of stable bicelles. We use a combination of dynamic light scattering, small-angle X-ray scattering and cryogenic electron microscopy to perform a systematic sample characterization, thus providing a set of conditions under which bicelles can be successfully formed.