Nutrients Export by Rivers to the Coastal Waters of Africa: Past and Future trends

We analyze past and future trends in nitrogen (N), phosphorus (P), and carbon (C) export by rivers to the coastal waters of Africa as calculated by the Global Nutrient Export to WaterShed (NEWS) models for the period 1970–2050. Between 1970 and 2000 the total nutrient export by African rivers increased by 10–80%. For future years (2000–2050) we calculate an increase in the total loads of dissolved forms of N and P, but decreasing trends for dissolved organic C and particulate forms of N and P. There are large regions that deviate from these pan-African trends. We explore the regional patterns and the underlying processes, in particular for the Nile, Zaire, Niger, and Zambezi. In the future, anthropogenic sources may, in large parts of Africa, become larger contributors to riverine nutrient loads than natural source

Electrostatic Structures in Space Plasmas: Stability of Two-dimensional Magnetic Bernstein-Greene-Kruskal Modes

Electrostatic structures have been observed in many regions of space plasmas, including the solar wind, the magnetosphere, the auroral acceleration region, and in association with shocks, turbulence, and magnetic reconnection. Due to potentially large amplitude of electric fields within these structures, their effects on particle heating, scattering, or acceleration can be important. One possible theoretical description of some of these structures is the concept of Bernstein-Greene-Kruskal (BGK) modes, which are exact nonlinear solutions of the Vlasov-Poisson system of equations in collisionless kinetic theory. BGK modes have been studied extensively for many decades, predominately in one dimension (1D), although there have been observations showing that some of these structures have clear 3D features. While there have been approximate solutions of higher dimensional BGK modes, an exact 3D BGK mode solution in a finite magnetic field has not been found yet. Recently we have constructed exact solutions of 2D BGK modes in a magnetized plasma with finite magnetic field strength in order to gain insights of the ultimate 3D theory [Ng, Bhattacharjee, and Skiff, Phys. Plasmas 13, 055903 (2006)]. Based on the analytic form of these solutions, as well as Particle-in-Cell (PIC) simulations, we will present numerical studies of their stability for different levels of background magnetic field strength.Comment: Submitted to AIP Journal Proceedings for "Tenth Annual International Astrophysics Conference

Soil Particle Size by Time-weight Accumulation of Sedimentation

The principal reason for measuring particle size distribution is for the utilization of the relationships that exist between particle size and soil performance characteristics. The most interesting property of finely divided substance is the tremendous surface-to-weight ratio which they possess. The surface-to-weight ratio varies inversely with the square of the particle diameter. Thus, properties of particles which depend upon the amount of exposed surface are generally influenced by the size of the particles. Also, grain size distribution is very useful in the field of soils engineering. Particles size are measured by several methods and every method is not suitable for all purposes. The most promising and the most widely used methods for determining particle size distributions in the subseive range are based on sedimentation because they are simple to preform, give accurate results, and require inexpensive equipment. The sedimentation methods are of two types. The first type is known as the incremental method. Pipette, hydrometer, and photoextinction are examples of this method. The measurements are made to determine changes in the concentration in a setting suspension. The second type, called cumulative, involves the measurement if the overall accumulation of the settled suspension, usually by a balance introduced into the sedimentation. In all conventional sedimentation methods, which employ a uniform suspension, it is necessary to differentiate the sedimentation curve in order to evaluate the size distribution. The method described in this thesis has an advantage over the others because it does not necessitate such differentiation, which is very tedious and time consuming. A further advantage is that it is unnecessary to make an accurate distribution of the initial weight. Particle size distribution curves for three different samples were plotted from weight accumulation test data as well as hydrometer test data. Comparative tests with the hydrometer analysis confirm the reliability of this testing procedure

Mobility-Dependence of the Critical Density in Two-Dimensional Systems: An Empirical Relation

For five different electron and hole systems in two dimensions (Si MOSFET's, p-GaAs, p-SiGe, n-GaAs and n-AlAs), the critical density, $n_c$ that marks the onset of strong localization is shown to be a single power-law function of the scattering rate $1/\tau$ deduced from the maximum mobility. The resulting curve defines the boundary separating a localized phase from a phase that exhibits metallic behavior. The critical density $n_c \to 0$ in the limit of infinite mobility.Comment: 2 pages, 1 figur

Pemodelan General Regression Neural Network (Grnn) Pada Data Return Indeks Harga Saham Euro 50

General Regression Neural Network (GRNN) merupakan salah satu model jaringan radial basis yang digunakan untuk pendekatan suatu fungsi. Model GRNN termasuk model jaringan syaraf tiruan dengan solusi yang cepat, karena tidak diperlukan iterasi yang besar pada estimasi bobot-bobotnya. Model ini memiliki arsitektur jaringan yang baku, dimana jumlah unit pada pattern layer sesuai dengan jumlah data input. Salah satu aplikasi GRNN adalah untuk memprediksi nilai return saham dari indeks Euro 50 CFD (Contract For Difference). Indeks Euro 50 CFD (Contract For Difference) digunakan sebagai patokan harga saham dari 50 Perusahaan terbesar di zona Eropa. Para investor melakukan investasi di saham indeks Euro 50 CFD (Contract For Difference) dengan harapan mendapatkan kembali keuntungan yang sesuai dengan apa yang telah di investasikannya. Dengan menggunakan model GRNN diperoleh bahwa nilai RMSE dan R2 untuk data training sebesar 0,00095 dan 99,19%. Untuk data testing diperoleh nilai RMSE dan R2 sebesar 0,00725 dan 98,46%. Berdasarkan nilai prediksi return saham dua belas hari ke depan diperoleh kerugian tertinggi atau capital loss pada 15 Desember 2014 sebesar 5,583188% dan profit tertinggi atau capital gain pada tanggal 10 Desember 2014 sebesar 2,267641% Kata Kunci: GRNN, Jaringan Syaraf Tiruan, Return Saham, Indeks Euro 50, Kerugian Tertinggi, Profit Tertinggi, Prediks

Analisis Biplot Komponen Utama Pada Bank Umum (Commercial Bank) Yang Beroperasi Di Jawa Tengah

Competition among banks in Indonesia nowadays are getting higher due to the good economic growth and increasing of middle social class in Indonesia. The number of banks cause high competition among banks and internal bank itselves. This high competition makes the management of the bank should think seriously to maintain its existence. In this case the assessment of the bank become very important in the banking business to survive in today\u27s banking industry. This study was conducted to determine how competitive the Commercial Bank are operating in Central Java by a method of Principal Component Biplots. This analysis can be applied to find out information about the relative position, the similarity between objects and characteristic of variables in the three categories of commercial banks operating in Central Java based on their health aspects. The results of this study are the banks from each category have a distinct predominance in every aspect of health assessment variable. In addition, the biplots can give information on the variability more than 70% which means that principal component biplot explains the overall data well