Attention Correctness in Neural Image Captioning

Attention mechanisms have recently been introduced in deep learning for various tasks in natural language processing and computer vision. But despite their popularity, the "correctness" of the implicitly-learned attention maps has only been assessed qualitatively by visualization of several examples. In this paper we focus on evaluating and improving the correctness of attention in neural image captioning models. Specifically, we propose a quantitative evaluation metric for the consistency between the generated attention maps and human annotations, using recently released datasets with alignment between regions in images and entities in captions. We then propose novel models with different levels of explicit supervision for learning attention maps during training. The supervision can be strong when alignment between regions and caption entities are available, or weak when only object segments and categories are provided. We show on the popular Flickr30k and COCO datasets that introducing supervision of attention maps during training solidly improves both attention correctness and caption quality, showing the promise of making machine perception more human-like.Comment: To appear in AAAI-17. See http://www.cs.jhu.edu/~cxliu/ for supplementary materia

Negative feedback effects on star formation history and cosmic reionization

After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_vir<10000 K$) that are thought to breed the first stars at early time, the radiative feedback gets stronger when the redshift decreases. And the star formation rate in these small halos depends very weakly on the star-formation efficiency. Our results show that the radiative feedback is important for the early generation stars. It can suppress the star formation rate considerably. But the mechanical feedback from the SNe explosions is not able to affect the early star formation significantly. The early star formation in small-halo objects is likely to be self-regulated. The radiative and mechanical feedback dominates the star formation rate of the PopII/I stars all along. The feedback from first generation stars is very strong and should not be neglected. However, their effects on the cosmic reionization are not significant, which results in a small contribution to the optical depth of Thomson scattering.Comment: 12 pages,6 figure

Analysis of the Herbicides Chlorsulfuron, Sulfometuron Methyl and Metsulfuron Methyl in Soil and Water

Chlorsulfuron, sulfometuron methyl and metsulfuron methyl are new herbicides. They are effective in controlling weeds in different areas. Generally, they are applied at very low levels. Their decomposition rates vary with soil moisture, pH, etc. Since they may be used year after year and their decomposition rates are not very rapid in this climate, the persistence can be a problem with herbicide carryover harming crops in the following years. Therefore, there is a need for a method to measure very low levels of these herbicides in soil and water to ensure that the quantities which might be present are not sufficiently large to be injurious to agricultural crops. The objective of my thesis research was to develop a method to determine herbicides chlorsulfuron, sulfometuron methyl and metsulfuron methyl in soil and water and estimate the detection limits with the instruments available in this school. Much of my work involved efforts to improve detection levels, and this involved a study of a number of extractions, cleanup and chromatography methods

Will Decline in Foreign Trade Reshape Internal Economic Geography? Simulations in an Estimated Model of the Chinese Space-economy

This study evaluates the role of decline in foreign trade in shaping China’s internal economic Geography. In a first step, we develop a multi-region multi-industry economic geography model under Cournot competition, of which we estimate the parameter values from real regional and industry data to obtain a predictable model. Next, we set some scenarios reflecting a decline in export to simulate the evolution of industrial spatial pattern. The simulations indicate the evident impact of decreasing export on the spatial distribution of industries; besides, the degree of influence varies across different industries. Moreover, the decline in export of one industry not only influences its own location, but also the location of the forward or backward-linked industries. However, the general spatial pattern, observed after policy reforms and trade liberalization, will not be reversed due to export recession in China