Adaptive encoding of zoomable video streams based on user access pattern

Zoomable video allows users to selectively zoom and pan into regions of interest within the video for viewing at higher resolutions. Such interaction requires dynamic cropping of RoIs on the source video. We have previously explored two different ways of encoding and transmitting video to support dynamic RoI cropping: (i) Monolithic streaming uses a standard video encoder to encode the video. When an RoI is requested, the bits belonging to the RoI along with other bits required to decode the RoIs (due to encoding dependencies) are transmitted. (ii) Tile streaming divides regions in the standard video into rectangular tiles that are encoded independently. The tiles that intersect with a requested RoI are transmitted. In this paper, we consider how the bandwidth needed to transmit the RoIs can be reduced by carefully encoding the source video for each of the two encoding schemes. The goal is to support bandwidth efficient compressed domain RoI cropping in the context of virtual zoom and pan by tuning encoder parameters. Our key idea is to exploit user access patterns to the RoIs, and encode different regions of the video with different encoding parameters based on the popularity of the region. We show that our encoding method can reduce the expected bandwidth by up to 43% in the test video sequence which we have used.     

Identification of peptide-mediated interactions between human PTTG and SH3 domains in pALL gene expression profile

Human pituitary tumor-transforming gene (PTTG) plays an essential role in the development and progression of pediatric acute lymphoblastic leukemia (pALL). PTTG has two SH3-binding peptide motifs that can be recognized by a variety of SH3-containing proteins in the pALL through peptide-mediated interactions. In this study, the gene expression profile of pALL was examined in detail by integrating computational modeling and experimental assay, aiming to identify those potential partner proteins of human PTTG. The binding potency of domain candidates to peptide motifs was ranked using knowledge-based scoring and fluorescence titration. A number of SH3 domains found in a variety of pALL proteins were identified as potent binders with moderate or high affinity for PTTG. It is revealed that the PTTG peptide motifs show different affinity profiles for various candidate proteins, indicating that the PTTG selectivity is optimized across pALL gene expression space. The PTTG peptides were then mutated rationally to target the SH3 domains of identified partner proteins by competing with the native peptide motifs.     

Real‐Time and High‐Resolution Bioimaging with Bright Aggregation‐Induced Emission Dots in Short‐Wave Infrared Region

Fluorescence imaging in the spectral region beyond the conventional near‐infrared biological window (700–900 nm) can theoretically afford high resolution and deep tissue penetration. Although some efforts have been devoted to developing a short‐wave infrared (SWIR; 900–1700 nm) imaging modality in the past decade, long‐wavelength biomedical imaging is still suboptimal owing to the unsatisfactory materials properties of SWIR fluorophores. Taking advantage of organic dots based on an aggregation‐induced emission luminogen (AIEgen), herein microscopic vasculature imaging of brain and tumor is reported in living mice in the SWIR spectral region. The long‐wavelength emission of AIE dots with certain brightness facilitates resolving brain capillaries with high spatial resolution (≈3 µm) and deep penetration (800 µm). Owning to the deep penetration depth and real‐time imaging capability, in vivo SWIR microscopic angiography exhibits superior resolution in monitoring blood–brain barrier damage in mouse brain, and visualizing enhanced permeability and retention effect in tumor sites. Furthermore, the AIE dots show good biocompatibility, and no noticeable abnormalities, inflammations or lesions are observed in the main organs of the mice. This work will inspire new insights on development of advanced SWIR techniques for biomedical imaging.     

微波辅助合成N-苯基哌嗪盐酸盐

在微波辅助下研究重要中间体N-苯基哌嗪盐酸盐合成的最佳条件。在微波辅助下苯胺与N,N-双(2-氯乙基)胺盐酸盐在溶剂乙二醇中经环合反应合成目标化合物。探讨了微波辐射时间、辐射温度、溶剂量、加入原料的摩尔比(苯胺∶N,N-双(2-氯乙基)胺盐酸盐)等因素对环化产率的影响。以最优化条件得到N-苯基哌嗪盐酸盐,最佳条件为:原料的摩尔比(苯胺∶N,N-双(2-氯乙基)胺盐酸盐)=1.0∶0.9,乙二醇的量与苯胺比为1mL∶5mmol,微波反应时间为15min,微波反应温度为120℃,收率84.34%。其结构经熔点、IR和1 H NMR和质谱与目标化合物的结构一致。该路线工艺流程简单、快速,三废少且易处理。     

Dielectric and ferroelectric properties of phosphoric acid doped triglycine sulfate single crystals

Single crystals of triglycine sulfate (TGS) grown with 25–50 mol% phosphoric acid dopant in solution were investigated for their dielectric, ferroelectric and mechanical hardness properties. A 25 mol% of H₃PO₄ in solution yielded crystals with a large area in the ac plane without any seed crystal. The room temperature (300 K) dielectric constant (ε′) and tan δ in the frequency range 0.1–100 kHz were found to increase with increasing phosphoric acid concentration. A maximum shift of 2.5 K in the phase transition temperature (T_c) is observed for crystals grown with 50 mol% of H₃PO₄. Systematic lowering of Curie–Weiss constant (C_f) in ferroelectric phase and an increase in the paraelectric phase (C_p) indicates domain wall clamping effects in the doped samples. The changes in the spontaneous polarization (2.6–3.2 μC cm⁻²) with phosphoric acid doping are insignificant, but the high coercive fields (E_c=5 kV cm⁻¹), and distorted loops indicate the presence of stresses and inhomogeneities. The activation energy (ΔE) from temperature dependent d.c. conductivity measurements is lower in both the ferroelectric and the paraelectric phase for doped crystals indicating a strong influence of dopants on the conduction process. The microhardness of the doped crystals is lower in comparison to undoped TGS.