The Mechanism of Additive Composition

Additive composition (Foltz et al, 1998; Landauer and Dumais, 1997; Mitchell and Lapata, 2010) is a widely used method for computing meanings of phrases, which takes the average of vector representations of the constituent words. In this article, we prove an upper bound for the bias of additive composition, which is the first theoretical analysis on compositional frameworks from a machine learning point of view. The bound is written in terms of collocation strength; we prove that the more exclusively two successive words tend to occur together, the more accurate one can guarantee their additive composition as an approximation to the natural phrase vector. Our proof relies on properties of natural language data that are empirically verified, and can be theoretically derived from an assumption that the data is generated from a Hierarchical Pitman-Yor Process. The theory endorses additive composition as a reasonable operation for calculating meanings of phrases, and suggests ways to improve additive compositionality, including: transforming entries of distributional word vectors by a function that meets a specific condition, constructing a novel type of vector representations to make additive composition sensitive to word order, and utilizing singular value decomposition to train word vectors.Comment: More explanations on theory and additional experiments added. Accepted by Machine Learning Journa

REGULATORY NETWORKS DURING SEED DEVELOPMENT

Seeds make up approximately 70% of the human diet directly so understanding regulatory mechanisms to generate a seed and the embryo it contains is fundamentally important. The LAFL genes encode transcription factors (TF) that are critical for seed development. Three members of LAFL, LEAFY COTYLEDON2 (LEC2), ABSCISIC ACID3 (ABI3) and FUSCA3 (FUS3), are B3 domain factors that bind DNA motifs called RY motifs. While LEC2 is expressed earlier in embryo development, ABI3 and FUS3 are expressed during later development. All three of these TFs can induce embryo-specific programs after completion of germination to different extents up to and including formation of embryos in a process called somatic embryogenesis (SE). ABI3 also contributes to the abscisic acid (ABA) response. Prior work determined direct and indirect targets of FUS3. Here we report on chromatin immunoprecipitation-tiling array experiments to globally map binding sites for ABI3. We also assessed transcriptomes in response to ABI3 by comparing developing abi3-5 and wild type seeds and combine this information to ascertain direct and indirect responsive ABI3 target genes. ABI3 can directly induce and repress its target genes’ transcript accumulation and some intriguing differences exist in cis motifs between these groups of genes. Directly regulated targets reflect ABI3’s roles in seed maturation, desiccation tolerance, entry into a quiescent state and longevity. Interestingly, ABI3 directly represses a gene encoding a microRNA (MIR160B) that targets AUXIN RESPONSE FACTOR (ARF)10 and ARF16 that are involved in establishment of dormancy. In addition, ABI3, like FUS3, regulates genes encoding MIR156 but while FUS3 only induces genes encoding this product, ABI3 induces these genes during early stages of seed development, but represses these genes during late development. The interplay between ABI3, the other LAFL genes, and the VP1/ABI3-LIKE (VAL) genes that are involved in the transition to seedling development are examined and reveal complex interactions controlling development. ABI3 directly regulates all five DUF1264 (Domain of Unknown Function 1264) members in Arabidopsis, while two other seed transcription factors FUS3 and AGL15 directly control subsets of genes in this family. Arabidopsis genes designated as DUF1264s appear to be expressed specifically within seeds and the encoded protein include a domain of unknown function that is highly conserved in various plants. Here, the direct association of the TFs with these genes and effect on transcript accumulation is verified. Also, higher order mutants were generated. Quadruple duf1264 mutant shows a reduction in SE compared to wild type control. Pentuple duf1264 mutant shows a hypersensitive response in seedlings to ABA compared to WT. In an associated project, an Arabidopsis protein called SIN3A associated polypeptide 18 (AtSAP18) was investigated. SAP18 is a transcriptional co-regulator that is a component of histone deacetylase (HDAC) complexes which interacts with a TF of interest in the lab, AGL15 to control embryogenesis. A new phenotype of a loss-of-function mutant sap18 was documented in that the mutant is hypersensitive to ABA treatment compared to Columbia (Col) wild type (WT), suggesting an important role of SAP18 in modulation of ABA response. Finally, the global targets of AGL15 were identified by combining previous RNA microarrays and ChIP microarrays with RNA-seq and ChIP-seq in this study. Also, some of these regulatory networks were investigated in the important crop plant, Glycine max

Exception Management Application

iProcess is a standardized software tool developed by TIBCO that has been used for business process management (BPM) at Barclays. The objective of iProcess is to automate the business processes in which human activities are often involved. The main task of this MQP project is to conduct research into iProcess and to build a framework for the development of exception management applications. Exceptions are referred to cases that deviate from normal situation and need to be handled by human interventions, such as missing static data or incorrect trade date in the trade information database. This framework will be adopted by Barclays to develop programs that can detect and close many types of exceptions across multiple systems

Time domain analysis of superradiant instability for the charged stringy black hole-mirror system

It has been proved that the charged stringy black holes are stable under the perturbations of massive charged scalar fields. However, superradiant instability can be generated by adding the mirror-like boundary condition to the composed system of charged stringy black hole and scalar field. The unstable boxed quasinormal modes have been calculated by using both analytical and numerical method. In this paper, we further provide a time domain analysis by performing a long time evolution of charged scalar field configuration in the background of the charged stringy black hole with the mirror-like boundary condition imposed. We have used the ingoing Eddington-Finkelstein coordinates to derive the evolution equation, and adopted Pseudo-spectral method and the forth-order Runge-Kutta method to evolve the scalar field with the initial Gaussian wave packet. It is shown by our numerical scheme that Fourier transforming the evolution data coincides well with the unstable modes computed from frequency domain analysis. The existence of the rapid growth mode makes the charged stringy black hole a good test ground to study the nonlinear development of superradiant instability.Comment: 7 pages, 6 figures, and 5 tables. References adde