Visualizing the transition to chaos in the Lorenz system

The Lorenz system still fascinates many people because of the simplicity of the equations that generate such complicated dynamics on the famous butterfly attractor. This paper addresses the role of the global stable and unstable manifolds in organising the dynamics. More precisely, for the standard system parameters, the origin has a two-dimensional stable manifold and the other two equilibria each have a two-dimensional unstable manifold. The intersections of these manifolds in the three-dimensional phase space form heteroclinic connections from the nontrivial equilibria to the origin. A parameter-dependent visualization of these manifolds clarifies the transition to chaos in the Lorenz syste

Analisis Faktor-faktor yang Mempengaruhi Perilaku Konsumen dalam Mengkonsumsi Daging Ayam Kampung di Kota Medan (Studi Kasus: Pasar Sambas, Medan)

Tujuan dari penelitian ini adalah untuk mengetahui perkembangan permintaan konsumen terhadap daging ayam kampung dan harga ayam kampung; untuk mengetahui perilaku konsumen terhadap konsumsi daging ayam kampung di Kota Medan dan untuk menganalisis faktor-faktor yang mempengaruhi konsumsi daging ayam kampung di Pasar Sambas, Kota Medan. Metode analisis yang digunakan dalam penelitian ini adalah metode analisis regresi linier berganda menggunakan alat bantu SPSS 16. Penentuan daerah penelitian dilakukan secara purposive. Teknik pengambilan sampel dengan metode accidental sampling dengan jumlah sampel 30 konsumen. Penelitian ini dilakukan pada bulan Mei sampai Juli tahun 2013. Hasil penelitian menunjukkan bahwa dari hasil estimasi dapat diperoleh nilai determinasi (R2) sebesar 0,707. Hal ini berarti 70,7% variasi yang terjadi pada variabel umur, tingkat pendidikan, jumlah tanggungan, pendapatan dan harga daging ayam kampung dapat menjelaskan jumlah konsumsi daging ayam kampung, sedangkan 29,3% lagi dipengaruhi oleh variabel lain. Secara serempak menunjukkan bahwa dari keseluruhan variabel bebas memberikan pengaruh yang nyata terhadap jumlah konsumsi daging ayam kampung. Secara parsial variabel jumlah tanggungan dan pendapatan berpengaruh nyata terhadap jumlah konsumsi daging ayam kampung, sedangkan pada umur, tingkat pendidikan dan harga daging ayam kampung tidak berpengaruh nyata terhadap jumlah konsumsi daging ayam kampung

Pour une agriculture intelligente face au changement climatique au Sénégal: Recueil de bonnes pratiques d'adaptation et d'atténuation

Climate change is at the present time a new threat which leads to increased frequency and intensity of floods, droughts and cyclones with rising sea levels; thus placing additional demands on a situation already critical in rural areas. In Senegal, as in many countries of the Sahel, those natural phenomena result in a significant drop in harvests, water shortages and worsening health crisis which leads to consequences such as growing food insecurity of the population; thus threatening the progress achieved in regards with the fight against poverty during the last century. Indeed, many farmers live in rural areas which are characterized as low rainfall, saline soils, fragile or degraded soils and limited market access areas. The poverty in which they live, especially those of women, is often worsened by social exclusion. Such farmers are vulnerable because they depend directly on rainfall and seasons. They have little savings while supports from the government or their local authorities remain inadequate. It is essential to strengthen the adaptive capacity of vulnerable countries and communities to cope with the impacts of climate change on agriculture and food security. This document is the result of a multi-criteria analysis of experiences of tackling climate variability, drought and desertification, and land degradation on one hand, and Adaptation to Climate Change in Senegal on the other. It is carried out on the initiative of the national platform for science-policy dialogue on adaptation of agriculture and food security to climate change (C-CASA) for capacity building and informed decision making for adaptation to climate change. This work has received technical and financial support from CCAFS Program (www.ccafs.cgiar.org). It is intended for the use of field workers in the area of adaptation to climate change. It also serves as technologies and tools guide to adapt to climate change impacts in the area of agriculture and food security. The manual is based primarily on (1) both the institutional and peasant experiences of the actors; (2) the recommendations of the reports of the Inter-governmental Panel on Climate Change (IPCC); (3) the procedures manual for assessing climate change impacts and adaptation strategies; (4) the results of development projects and applied research. This is a collection that comes as a complement to other initiatives in the country and ongoing operations which provide practical examples of using the technological options for successful implementation of projects and programs and for the definition of agricultural policies in the Sahel