Replacing the Irreplaceable: Fast Algorithms for Team Member Recommendation

In this paper, we study the problem of Team Member Replacement: given a team of people embedded in a social network working on the same task, find a good candidate who can fit in the team after one team member becomes unavailable. We conjecture that a good team member replacement should have good skill matching as well as good structure matching. We formulate this problem using the concept of graph kernel. To tackle the computational challenges, we propose a family of fast algorithms by (a) designing effective pruning strategies, and (b) exploring the smoothness between the existing and the new team structures. We conduct extensive experimental evaluations on real world datasets to demonstrate the effectiveness and efficiency. Our algorithms (a) perform significantly better than the alternative choices in terms of both precision and recall; and (b) scale sub-linearly.Comment: Initially submitted to KDD 201

Degradation of Wood Flour/Poly (Lactic Acid) Composites Reinforced by Coupling Agents and Organo-Montmorillonite in a Compost Test

To investigate the degradation properties of wood flour (WF)/poly (lactic acid) (PLA) composites modified with organo-montmorillonite (OMMT) and two types of coupling agents, namely, maleic anhydride grafted polypropylene (MAPP) and silane (γ-methacryloxypropyltrimethoxysilane, KH-570), pure PLA, OMMT/PLA, and WF/PLA composites were prepared with the hot-press molding method and tested in a compost test for 6 mo. After compost tests, samples were also characterized with scanning electron microscopy, Fourier transform infrared spectrum, and differential scanning calorimeter for further understanding. The results showed that 1) introducing WF and OMMT accelerated the degradability of PLA (after 5 mo, all composites were completely degraded, whereas the pure PLA control still had 4.78% residue); 2) the two types of coupling agents had opposite effects on degradation of WF/PLA composites (MAPP delayed the degradation process, whereas silane accelerated it); 3) silane and OMMT had a synergic effect on degradability, which was supported by the complete degradation of WF/PLA composites modified with both silane and OMMT in 4 mo; 4) after a 3-mo compost, many cracks or voids occurred on the surface of PLA, and this compost test also resulted in separated WF. Tm values of PLA and OMMT/PLA decreased and their crystallinity degrees increased, suggesting faster degradation of PLA with WF and OMMT loading

The MES-2/MES-3/MES-6 Complex and Regulation of Histone H3 Methylation in C. elegans

The C. elegans proteins MES-2 and MES-6, orthologs of the Polycomb group (PcG) chromatin repressors E(Z) and ESC [1, 2], exist in a complex with their novel partner MES-3 [3]. The MES system participates in silencing the X chromosomes in the hermaphrodite germline [4, 5]. Loss of maternal MES function leads to germline degeneration and sterility [6]. We report here that the MES complex is responsible for di- and trimethylation of histone H3 Lys27 (H3-K27) in the adult germline and in early embryos and that MES-dependent H3-K27 marks are concentrated on the X's. Another H3-K27 HMT functions in adult somatic cells, oocytes, and the PGCs of embryos. In PGCs, the MES complex may specifically convert dimethyl to trimethyl H3-K27. The HMT activity of the MES complex appears to be dependent on the SET domain of MES-2. MES-2 thus joins its orthologs Drosophila E(Z) and human EZH2 among SET domain proteins known to function as HMTs (reviewed in [7]). Methylation of histones is important for long-term epigenetic regulation of chromatin and plays a key role in diverse processes such as X inactivation and oncogenesis [8]. Our results contribute to understanding the composition and roles of E(Z)/MES-2 complexes across species

Effects of the α\alpha-cluster structure and the intrinsic momentum component of nuclei on the longitudinal asymmetry in relativistic heavy-ion collisions

The longitudinal asymmetry in relativistic heavy-ion collisions arises from the fluctuation in the number of participating nucleons. This asymmetry causes a rapidity shift in the center of mass of the participant zone. Both the rapidity shift and the longitudinal asymmetry have been found to be significant at the top LHC energy for collisions of identical nuclei. However, much discussion of the longitudinal asymmetry has treated the initial condition as a non-zero momentum only contributed only by the number of participants, i.e., the asymmetry depends only on the number of participating nucleons. In this work, we consider other effects on the longitudinal asymmetry other than fluctuation in the number of participants, e.g. the intrinsic momentum distribution as well as $\alpha$-clustering structure in the target or projectile nuclei for the collisions in the framework of a multiphase transport (AMPT) model. By introducing systems with different $\alpha$-clustering structure and intrinsic momentum distribution, we calculated ratio of different systems' rapidity distribution and extracted expansion coefficient to analyze the difference contributed by these factors. And we investigated the possible effect of non-Gaussian distribution on the rapidity distribution. These results may help us to constrain the initial conditions in ultra-relativistic heavy-ion collisions, and suggest a quantitative correction on final state measurement and a possible correlation between the initial condition and the final-state observable in LHC and RHIC energy.Comment: 10 pages, 5 figure

The MES-2/MES-3/MES-6 Complex and Regulation of Histone H3 Methylation in C. elegans

The C. elegans proteins MES-2 and MES-6, orthologs of the Polycomb group (PcG) chromatin repressors E(Z) and ESC [1, 2], exist in a complex with their novel partner MES-3 [3]. The MES system participates in silencing the X chromosomes in the hermaphrodite germline [4, 5]. Loss of maternal MES function leads to germline degeneration and sterility [6]. We report here that the MES complex is responsible for di- and trimethylation of histone H3 Lys27 (H3-K27) in the adult germline and in early embryos and that MES-dependent H3-K27 marks are concentrated on the X's. Another H3-K27 HMT functions in adult somatic cells, oocytes, and the PGCs of embryos. In PGCs, the MES complex may specifically convert dimethyl to trimethyl H3-K27. The HMT activity of the MES complex appears to be dependent on the SET domain of MES-2. MES-2 thus joins its orthologs Drosophila E(Z) and human EZH2 among SET domain proteins known to function as HMTs (reviewed in [7]). Methylation of histones is important for long-term epigenetic regulation of chromatin and plays a key role in diverse processes such as X inactivation and oncogenesis [8]. Our results contribute to understanding the composition and roles of E(Z)/MES-2 complexes across species