Image Collage on Arbitrary Shape via Shape-Aware Slicing and Optimization.

Image collage is a very useful tool for visualizing an image collection. Most of the existing methods and commercial applications for generating image collages are designed on simple shapes, such as rectangular and circular layouts. This greatly limits the use of image collages in some artistic and creative settings. Although there are some methods that can generate irregularly-shaped image collages, they often suffer from severe image overlapping and excessive blank space. This prevents such methods from being effective information communication tools. In this paper, we present a shape slicing algorithm and an optimization scheme that can create image collages of arbitrary shapes in an informative and visually pleasing manner given an input shape and an image collection. To overcome the challenge of irregular shapes, we propose a novel algorithm, called Shape-Aware Slicing, which partitions the input shape into cells based on medial axis and binary slicing tree. Shape-Aware Slicing, which is designed specifically for irregular shapes, takes human perception and shape structure into account to generate visually pleasing partitions. Then, the layout is optimized by analyzing input images with the goal of maximizing the total salient regions of the images. To evaluate our method, we conduct extensive experiments and compare our results against previous work. The evaluations show that our proposed algorithm can efficiently arrange image collections on irregular shapes and create visually superior results than prior work and existing commercial tools.

Anti-Acetylcholinesterase Alkaloids from Annona glabra Leaf.

Bioassay guided fractionation and separation of the EtOH extract of Annona glabra leaf against acetylcholinesterse led to the characterization of 15 alkaloids. Among them, (-)-actinodaphnine (2) and (-)-(6aS,7R)-7-hydroxyactinodaphnine (9) are new aporphines, although (+)-2 and (±)-2 have been found in several plants. Their structures were established by spectroscopic analysis. (-)-Anolobine (5) and (-)-roemeroline (8) showed moderate inhibitory activity against eel acetylcholinesterase with IC50 values of 22.4 and 26.3 µM, respectively.

Phase-matching spectral phase measurement and domain period reconstruction of aperiodic quasi-phase matched gratings by nonlinear spectral interferometry.

We experimentally measured the phase-matching spectral phases of aperiodic quasi-phase matched gratings for the first time (to the best of our knowledge) by nonlinear spectral interferometry. The retrieved information is useful in determining the temporal shape of the nonlinearly converted ultrafast signal and reconstructing the slowly-varying domain period distribution. The method is nondestructive, fast, sensitive, accurate, and applicable to different nonlinear materials. Compared to taking microscopic images of the etched crystal surface, our method can directly measure the domain period distribution in the crystal interior and is free of the artificial random duty period error due to image concatenation.

Healing-block-assisted quasi-phase matching.

A quasi-phase matching (QPM) structure based on phase correction by inserting a "healing block" (HB) of length d(HB) into M regular domains of constant length d is proposed to enhance the nonlinear conversion efficiency when the first-order QPM domain length d1 is too short to be reliably fabricated. Second-harmonic conversion efficiency 4.69 times higher than that of a third-order QPM grating has been experimentally demonstrated by using HB-QPM where all the domains are longer than 1.08d1.