Maize Production and Agricultural Policies in Central America and Mexico

This paper reviews trends in maize production and consumption in Central America and Mexico in the context of the political and economic changes taking place in the region since the 1970s. The authors focus on the effects of the structural adjustment programs in the 1980s and 1990s. The analysis begins by reviewing the economic context in which maize production occurs in the region and the main economic policy instruments affecting the maize economy. Next, trends in maize consumption and production are analyzed, along with the main factors influencing maize production, including trends in the public financing of maize research and extension. The authors find that several factors related to structural adjustment have defined--and are still defining--the course of agriculture, including maize production, in the countries of the region. The impact of these factors on maize production, consumption, and import trends has been different in Central America and in Mexico. In particular, the reduction or complete elimination of production incentives, the reduction of trade barriers, the liberalization of input and product prices, the deregulation of the currency exchange rate, the control of inflation, and the restructuring of agricultural research systems between the public and the private sectors have determined how basic grains are produced in the region and how they will be produced in the future. Furthermore, the visible and increasing deterioration of the natural resource base has raised great concern about the need to promote more sustainable, environmentally friendly uses of production systems and natural resources.Agricultural and Food Policy, Crop Production/Industries,

Instabilities and Spatio-temporal Chaos of Long-wave Hexagon Patterns in Rotating Marangoni Convection

We consider surface-tension driven convection in a rotating fluid layer. For nearly insulating boundary conditions we derive a long-wave equation for the convection planform. Using a Galerkin method and direct numerical simulations we study the stability of the steady hexagonal patterns with respect to general side-band instabilities. In the presence of rotation steady and oscillatory instabilities are identified. One of them leads to stable, homogeneously oscillating hexagons. For sufficiently large rotation rates the stability balloon closes, rendering all steady hexagons unstable and leading to spatio-temporal chaos.Comment: 26 pages, 9 jpeg figures. Postscript file with all figures included available at http://www.esam.northwestern.edu/~riecke/lit/lit.html Movies available at http://www.esam.northwestern.edu/~riecke/research/Marangoni/marangoni.htm

Clovis Blade Technology at the Topper Site (38AL23): Assessing Lithic Attribute Variation and Regional Patterns of Technological Organization

This monograph, by Douglas A. Sain, is based on his master’s thesis research on the organization of Clovis blade technology. This second monograph of the Occasional Papers series of the Southeastern Paleoamerican Survey closely follows the first in terms of the meticulousness of the study, and the new information it provides about the Topper Site. Detailed studies of Clovis material are eagerly sought by Paleoindian archaeologists, enthusiasts, and particularly by lithic analysts. Sain provides a well-rounded literature review for these groups, and an innovative approach to identifying technological blades. The “mixed assemblage” problem resulting when multiple lithic technologies were used at a single site is one with which lithic analysts continue to struggle. With a quarry site such as Topper and the wide variety of core forms and tools recovered, a nuanced and consistent approach to blade identification is a necessity if one wants to consider broader questions of technological organization. Recognizing variability in the end-product of blade manufacture and the relative importance of some characteristics over others, Sain weights six attributes from three to one and through detailed study of individual detached pieces produces a score. With a maximum value of 12, those with a score of seven or higher are considered a blade. This provides a consistent, replicable procedure for separating blades from blade-like flakes, and using these data in the consideration of Clovis lifeways. The small percentage of blades at Topper with modification, when coupled with a consideration of assemblages in the local and broader region, provide evidence that blades were part of a curated technology and toolkit, a transportable and reliable product that could be maintained as people moved across the landscape. This work provides a specific reconstruction of Clovis technological organization in the Savannah River Valley, and should inspire broader considerations of blade technology elsewhere in the Americas.https://scholarcommons.sc.edu/archanth_occasional_paleoam_papers/1001/thumbnail.jp

Alternatives for jet engine control

The development of models of tensor type for a digital simulation of the quiet, clean safe engine (QCSE) gas turbine engine; the extension, to nonlinear multivariate control system design, of the concepts of total synthesis which trace their roots back to certain early investigations under this grant; the role of series descriptions as they relate to questions of scheduling in the control of gas turbine engines; the development of computer-aided design software for tensor modeling calculations; further enhancement of the softwares for linear total synthesis, mentioned above; and calculation of the first known examples using tensors for nonlinear feedback control are discussed

Medium-throughput processing of whole mount in situ hybridisation experiments into gene expression domains

This is the final version of the article. Available from the publisher via the DOI in this record.Understanding the function and evolution of developmental regulatory networks requires the characterisation and quantification of spatio-temporal gene expression patterns across a range of systems and species. However, most high-throughput methods to measure the dynamics of gene expression do not preserve the detailed spatial information needed in this context. For this reason, quantification methods based on image bioinformatics have become increasingly important over the past few years. Most available approaches in this field either focus on the detailed and accurate quantification of a small set of gene expression patterns, or attempt high-throughput analysis of spatial expression through binary pattern extraction and large-scale analysis of the resulting datasets. Here we present a robust, "medium-throughput" pipeline to process in situ hybridisation patterns from embryos of different species of flies. It bridges the gap between high-resolution, and high-throughput image processing methods, enabling us to quantify graded expression patterns along the antero-posterior axis of the embryo in an efficient and straightforward manner. Our method is based on a robust enzymatic (colorimetric) in situ hybridisation protocol and rapid data acquisition through wide-field microscopy. Data processing consists of image segmentation, profile extraction, and determination of expression domain boundary positions using a spline approximation. It results in sets of measured boundaries sorted by gene and developmental time point, which are analysed in terms of expression variability or spatio-temporal dynamics. Our method yields integrated time series of spatial gene expression, which can be used to reverse-engineer developmental gene regulatory networks across species. It is easily adaptable to other processes and species, enabling the in silico reconstitution of gene regulatory networks in a wide range of developmental contexts.The laboratory of Johannes Jaeger and this study in particular was funded by the MEC-EMBL agreement for the EMBL/CRG Research Unit in Systems Biology, by grant 153 (MOPDEV) of the ERANet: ComplexityNET program, by SGR grant 406 from the Catalan funding agency AGAUR, by grant BFU2009-10184 from the Spanish Ministry of Science, and by European Commission grant FP7-KBBE-2011-5/289434 (BioPreDyn)

Pengaruh Alat Permainan Edukatif terhadap Aspek Perkembangan pada Anak PRA Sekolah di Wilayah Puskesmas Ondong Kabupaten Kepulauan Siau Tagulandang Biaro

Educated gane tool is a kind of gane which consists of educational value it is functioned to stimuli children\u27s imagination cognitively. The process is to give stimulus so it can increase the development skill and socializing a independency. The purpose of this research is to know the effect of educated game tool to preschool children development. The method of this research is one pre-post test group which the researcher observed before and after treatment. The sample is purposive sampling, total of the sampling is 17 respondent. Data which was gotten then analyzed by using wilcoxon signed ranks. The result of the research shows (p=0,000 < α=0,05), it means that there is effect from educated game tool to pre school childreen. From these result, it is suggested to parents a school to pay more attention to pre school children\u27s development especially speaking, language, socializing a independence ability

Predicting the coherence resonance curve using a semi-analytical treatment

Emergence of noise induced regularity or Coherence Resonance in nonlinear excitable systems is well known. We explain theoretically why the normalized variance ($V_{N}$) of inter spike time intervals, which is a measure of regularity in such systems, has a unimodal profile. Our semi-analytic treatment of the associated spiking process produces a general yet simple formula for $V_{N}$, which we show is in very good agreement with numerics in two test cases, namely the FitzHugh-Nagumo model and the Chemical Oscillator model.Comment: 5 pages, 5 figure