Results 1 - 10 of 4,936

1 Generating Plausible Crop Distribution Maps for Sub-Sahara Africa Using Spatial Allocation Model

by Liangzhi You, Stanley Wood
"... Readers may make verbatim copies of this document for non-commercial purposes by any means, provided that this copyright notice appears on all such copies. 2 Spatial data, which are data that include the coordinates (either by latitude/longitude or by other addressing methods) on the surface of the ..."
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we proposed a spatial allocation model. Using a classic cross-entropy approach, our spatial allocation model makes plausible allocations of crop production in geopolitical units (country, or state) into individual pixels, through judicious interpretation of all accessible

Generating plausible crop distribution and performance maps for Sub-Saharan Africa using a spatially disaggregated data fusion and optimization approach. Liangzhi

by Liangzhi You, Liangzhi You, Stanley Wood, Stanley Wood, Ulrike Wood-sichra, Ulrike Wood-sichra - FOOD POLICY RESEARCH INSTITUTE www.ifpri.org IFPRI HEADQUARTERS 2033 K Street, NW Washington, DC 20006-1002 USA Tel.: +1-202-862-5600 Fax: +1-202-467-4439 Email: ifpri@cgiar.org IFPRI ADDIS ABABA P. O. Box 5689 Addis Ababa, Ethiopia Tel.: +251 11 6463215 , 2007
"... of 15 agricultural research centers that receive principal funding from governments, private foundations, and international and regional organizations, most of which are members of the ..."
Abstract - Cited by 16 (3 self) - Add to MetaCart
of 15 agricultural research centers that receive principal funding from governments, private foundations, and international and regional organizations, most of which are members of the

Modeling and Forecasting Realized Volatility

by Torben G. Andersen, Tim Bollerslev, Francis X. Diebold, Paul Labys , 2002
"... this paper is built. First, although raw returns are clearly leptokurtic, returns standardized by realized volatilities are approximately Gaussian. Second, although the distributions of realized volatilities are clearly right-skewed, the distributions of the logarithms of realized volatilities are a ..."
Abstract - Cited by 549 (50 self) - Add to MetaCart
-frequency models, we find that our simple Gaussian VAR forecasts generally produce superior forecasts. Furthermore, we show that, given the theoretically motivated and empirically plausible assumption of normally distributed returns conditional on the realized volatilities, the resulting lognormal-normal mixture

Secure spread spectrum watermarking for multimedia

by Ingemar J. Cox, Joe Kilian, F. Thomson Leighton, Talal Shamoon - IEEE TRANSACTIONS ON IMAGE PROCESSING , 1997
"... This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i.i.d.) Gauss ..."
Abstract - Cited by 1100 (10 self) - Add to MetaCart
This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i

PCA versus LDA

by Aleix M. Martinez, Avinash C. Kak - IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE , 2001
"... In the context of the appearance-based paradigm for object recognition, it is generally believed that algorithms based on LDA (Linear Discriminant Analysis) are superior to those based on PCA (Principal Components Analysis) . In this communication we show that this is not always the case. We present ..."
Abstract - Cited by 472 (16 self) - Add to MetaCart
present our case first by using intuitively plausible arguments and then by showing actual results on a face database. Our overall conclusion is that when the training dataset is small, PCA can outperform LDA, and also that PCA is less sensitive to different training datasets. Keywords: face recognition

Randomized Experiments from Non-random Selection in the U.S. House Elections

by David S. Lee - Journal of Econometrics , 2008
"... This paper establishes the relatively weak conditions under which causal inferences from a regression-discontinuity (RD) analysis can be as credible as those from a randomized experiment, and hence under which the validity of the RD design can be tested by examining whether or not there is a discont ..."
Abstract - Cited by 377 (17 self) - Add to MetaCart
characteristics and choices, but there is also a random chance element: for each individual, there exists a well-defined probability distribution for V. The density function – allowed to differ arbitrarily across the population – is assumed to be continuous. It is formally established that treatment status here

The Political Economy of Government Responsiveness: Theory and Evidence from India

by Timothy Besley, Robin Burgess - CEPR DP
"... The determinants of government responsiveness to its citizens is a key issue in political economy. Here, we develop a model based on the solution of political agency problems. Having a more informed and politically active electorate strengthens incentives for governments to be responsive. This sugge ..."
Abstract - Cited by 347 (12 self) - Add to MetaCart
. This suggests that there is a role for both democratic institutions and mass media in ensuring that the preferences of citizens are reflected in policy. The ideas behind the model are tested on panel data from India. We show that state governments are more responsive to falls in food production and crop flood

Noun Classification From Predicate.argument Structures

by Donald Hindle , 1990
"... A method of determining the similarity of nouns on the basis of a metric derived from the distribution of subject, verb and object in a large text corpus is described. The resulting quasi-semantic classification of nouns demonstrates the plausibility of the distributional hypothesis, and has potent ..."
Abstract - Cited by 291 (0 self) - Add to MetaCart
A method of determining the similarity of nouns on the basis of a metric derived from the distribution of subject, verb and object in a large text corpus is described. The resulting quasi-semantic classification of nouns demonstrates the plausibility of the distributional hypothesis, and has

Local Feature Analysis: A general statistical theory for object representation

by Penio S. Penev, Joseph J. Atick , 1996
"... . Low-dimensional representations of sensory signals are key to solving many of the computational problems encountered in high-level vision. Principal Component Analysis has been used in the past to derive practically useful compact representations for different classes of objects. One major object ..."
Abstract - Cited by 285 (8 self) - Add to MetaCart
objection to the applicability of PCA is that it invariably leads to global, nontopographic representations that are not amenable to further processing and are not biologically plausible. In this paper we present a new mathematical construction---Local Feature Analysis (LFA)---for deriving local topographic

Distributional Information: A Powerful Cue for Acquiring Syntactic Categories

by Martin Redington, Nick Chater, Steven Finch - COGNITIVE SCIENCE , 1998
"... Many theorists have dismissed a priori the idea that distributional information could play a significant role in syntactic category acquisition. We demonstrate empirically that such information provides a powerful cue to syntactic category membership, which can be exploited by a variety of simple, p ..."
Abstract - Cited by 201 (9 self) - Add to MetaCart
, psychologically plausible mechanisms. We present a range of results using a large corpus of child-directed speech and explore their psychological implications. While our results show that a considerable amount of information concerning the syntac-tic categories can be obtained from distributional information
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