Short-term drought responses by seedlings of three maizes from contrasting environments in Michoacán, Mexico

Alterations in precipitation regimes resulting from climate change threaten countries like Mexico, where rainfed ag- riculture for subsistence is widespread. However, numerous local maizes are cultivated throughout the country’s territory originated from a substantial environmental diversity. To investigate whether an environmental specializa- tion exists, responses to drought by maizes from three sites (elevations of 689, 2379, and 3638 m) in the state of Michoacán, Mexico, were studied in a greenhouse experiment. Plants were watered every other day for 21 days since sowing. Watering was withheld during 26 d and followed by a 10 d recovery period during which watering was resumed. Environmental conditions were contrasting among the sites of origin, e.g., annual precipitation defi- cit (from an ombrotherm diagram) was 33% at the lowest site and 9% and 0.3% for the sites at higher elevations. At the greenhouse, substrate water content for the control was ca. 34% (w/w) over the course of the experiment, it decreased to 1.9% at 26 d of water withholding and recovered after resuming irrigation. Tissue water content was ca. 92% for the control and decreased by 22-33% (depending on its origin) for the droughted individuals at the peak of the drought. Dry mass was lower for droughted individuals than for the control at the end of the experi- ment. Leaf chlorophyll content tended to decrease with plant age, but did not respond to water withholding. In contrast, proline tended to increase for droughted individuals. The the content of polyphenols, free-radical scav- enging compounds, tended to decrease during the recovery period, but not during drought. Neither did the anti- oxidant activity of leaf tissue respond to water withholding. Germplasm that is able cope with novel environmental conditions seems to exist in Mexico. Future studies should survey yield responses to different drought intensities for various maizes from dry environments to help identify traits useful in future breeding programs

Statistically-Constrained High-Dimensional Warping Using Wavelet-Based Priors

In this paper, a Statistical Model of Deformation (SMD) that captures the statistical prior distribution of high-dimensional deformations more accurately and effectively than conventional PCA-based statistical shape models is used to regularize deformable registration. SMD utilizes a wavelet-based representation of statistical variation of a deformation field and its Jacobian, and it is able to capture both global and fine shape detail without overconstraining the deformation process. This approach is shown to produce more accurate and robust registration results in MR brain images, relative to the registration methods that use Laplacian-based smoothness constraints of deformation fields. In experiments, we evaluate the SMD-constrained registration by comparing the performance of registration with and without SMD in a specific deformable registration framework. The proposed method can potentially incorporate various registration algorithms to improve their robustness and stability using statistically-based regularization

Dialogue-Oriented Review Summary Generation for Spoken Dialogue Recommendation Systems

In this paper we present an opinion summarization technique in spoken dialogue systems. Opinion mining has been well studied for years, but very few have considered its application in spoken dialogue systems. Review summarization, when applied to real dialogue systems, is much more complicated than pure text-based summarization. We conduct a systematic study on dialogue-system-oriented review analysis and propose a three-level framework for a recommendation dialogue system. In previous work we have explored a linguistic parsing approach to phrase extraction from reviews. In this paper we will describe an approach using statistical models such as decision trees and SVMs to select the most representative phrases from the extracted phrase set. We will also explain how to generate informative yet concise review summaries for dialogue purposes. Experimental results in the restaurant domain show that the proposed approach using decision tree algorithms achieves an outperformance of 13% compared to SVM models and an improvement of 36% over a heuristic rule baseline. Experiments also show that the decision-tree-based phrase selection model can achieve rather reliable predictions on the phrase label, comparable to human judgment. The proposed statistical approach is based on domain-independent learning features and can be extended to other domains effectively

Utilizing Review Summarization in a Spoken Recommendation System

In this paper we present a framework for spoken recommendation systems. To provide reliable recommendations to users, we incorporate a review summarization technique which extracts informative opinion summaries from grass-roots users‘ reviews. The dialogue system then utilizes these review summaries to support both quality-based opinion inquiry and feature- specific entity search. We propose a probabilistic language generation approach to automatically creating recommendations in spoken natural language from the text-based opinion summaries. A user study in the restaurant domain shows that the proposed approaches can effectively generate reliable and helpful recommendations in human-computer conversations.T-Party ProjectQuanta Computer (Firm

Speech Communication

Contains reports on three research projects.U.S. Air Force Cambridge Research Laboratories under Contract F19628-72-C-0181National Institutes of Health (Grant 5 RO1 NS04332-09)Joint Services Electronics Programs (U.S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300M. I. T. Lincoln Laboratory Purchase Order CC-57

Eighty Challenges Facing Speech Input/Output Technologies

ABSTRACT During the past three decades, we have witnessed remarkable progress in the development of speech input/output technologies. Despite these successes, we are far from reaching human capabilities of recognizing nearly perfectly the speech spoken by many speakers, under varying acoustic environments, with essentially unrestricted vocabulary. Synthetic speech still sounds stilted and robot-like, lacking in real personality and emotion. There are many challenges that will remain unmet unless we can advance our fundamental understanding of human communication -how speech is produced and perceived, utilizing our innate linguistic competence. This paper outlines some of these challenges, ranging from signal presentation and lexical access to language understanding and multimodal integration, and speculates on how these challenges could be met

The MIT Summit Speech Recognition System: A Progress Report

Recently, we initiated a project to develop a phonetically-based spoken language understanding system called SUMMIT. In contrast to many of the past efforts that make use of heuristic rules whose development requires intense knowledge engineering, our approach attempts to express the speech knowledge within a formal framework using well-defined mathematical tools. In our system, features and decision strategies are discovered and trained automatically, using a large body of speech data. This paper describes the system, and documents its current performance

Fillings And Late Holocene Palaeoenvironments Of The Palustrine Depressions Of The Lopé National Park, Middle Ogooué Valley In Gabon

This work is devoted to the study of fillings and late Holocene palaeoenvironments of two marshes located in the savannas of the northern part of Lopé National Park in Gabon. Sedimentological and geochemical analyzes associated with 14C dating were performed on the sedimentary deposits of Yao and Vitex marshes. The results obtained were compared with these of the sedimentary core of the Lopé 2 marsh, previously analysed. All of these data show that the active filling of these marshes was carried out synchronously. The small variation observed are linked to specific physical characters to each of the marshes. This filling began between 2300 and 2000 cal years BP in all of the marshes. It started at the beginning of the humid climatic phase which followed the climatic pejoration recognized throughout the area of Atlantic Central Africa between 2500 and 2000 years BP. During this humid climatic phase, the rains were abundant and regular and the depressions were filled with sediments which are very rich coarse detrital elements from the erosion of slopes. The marshes and its banks were covered with sparse vegetation. Subsequently the sediments gradually become depleted in coarse detrital materials and enriched with organic constituents. This evolution would indicate a gradual reduction in erosion linked to the densification of the vegetation cover on the slopes. It is mostly related to the development of vegetation in the marshy basins. This development of the vegetation and the conservation of the organic matter of the marshes are due to the perennial flooding of the palustrine depressions