Boundary driven waveguide arrays: Supratransmission and saddle-node bifurcation

In this report, we consider a semi-infinite discrete nonlinear Schr\"odinger equation driven at one edge by a driving force. The equation models the dynamics of coupled waveguide arrays. When the frequency of the forcing is in the allowed-band of the system, there will be a linear transmission of energy through the lattice. Yet, if the frequency is in the upper forbidden band, then there is a critical driving amplitude for a nonlinear tunneling, which is called supratransmission, of energy to occur. Here, we discuss mathematically the mechanism and the source of the supratransmission. By analyzing the existence and the stability of the rapidly decaying static discrete solitons of the system, we show rigorously that two of the static solitons emerge and disappear in a saddle-node bifurcation at a critical driving amplitude. One of the emerging solitons is always stable in its existence region and the other is always unstable. We argue that the critical amplitude for supratransmission is then the same as the critical driving amplitude of the saddle-node bifurcation. We consider as well the case of the forcing frequency in the lower forbidden band. It is discussed briefly that there is no supratransmission because in this case there is only one rapidly decaying static soliton that exists and is stable for any driving amplitude.Comment: Some figures are removed due to file size limi

Communicative Competence in Teaching Speaking

The existence of Communicative Competence in teaching speaking is importantly viewed as the basis as well as the goal that must be achieved. Understanding the aspects and characteristics of Communicative Competence can help the speaking teachers to guide their learners into speaking atmosphere that make them speak naturally. Negotiation of meaning and management of interaction in communicative competence reflect to the focus on the use of language, not on the USAge. Oral communicative tasks given to students are the speaking teachers\u27 consideration to create students\u27 orally natural communication

Trade Creation and Trade Diversion in the North American Free Trade Agreement: The Case of Agricultural Sector

This paper examines the impact of the U.S.-Mexico trade agreement under NAFTA. The results suggest that U.S. agricultural imports from Mexico have been responsive to tariff rate reductions applied to Mexican products. A 1 percent decrease in tariff rates is associated with an increase in U.S. agricultural imports from Mexico by 3.96 percent in the first six years of NAFTA and by 1.07 percent in the last six years of NAFTA. US imports from Mexico have also been attributable to the pre-NAFTA tariff rates. Overall, the results indicate that the U.S.-Mexico trade agreement under NAFTA has been trade creating rather than trade diverting.International Relations/Trade,

Josephson tunneling of dark solitons in a double-well potential

We study the dynamics of matter waves in an effectively one-dimensional Bose-Einstein condensate in a double well potential. We consider in particular the case when one of the double wells confines excited states. Similarly to the known ground state oscillations, the states can tunnel between the wells experiencing the physics known for electrons in a Josephson junction, or be self-trapped. As the existence of dark solitons in a harmonic trap are continuations of such non-ground state excitations, one can view the Josephson-like oscillations as tunnelings of dark solitons. Numerical existence and stability analysis based on the full equation is performed, where it is shown that such tunneling can be stable. Through a numerical path following method, unstable tunneling is also obtained in different parameter regions. A coupled-mode system is derived and compared to the numerical observations. Regions of (in)stability of Josephson tunneling are discussed and highlighted. Finally, we outline an experimental scheme designed to explore such dark soliton dynamics in the laboratory.Comment: submitte

Market Integration in the North American Onion Markets: An Empirical Analysis Using Panel Data

This study investigates the level of market integration in the North American Onion Markets. A two-sample period analysis shows an increase in the speed of price convergence overtime, suggesting deeper market integration as NAFTA was fully implemented. Further analysis showed that U.S.-Canadian markets have experienced deeper market integration compared with U.S.-Mexican markets as well as Canadian-Mexican markets.market integration, onion markets, panel data, price convergence, Marketing,

Pengaruh Logam Dan Konsentrasi Substrat Terhadap Pertumbuhan Dan Aktivitas Bakteri Proteolitik Pada Proses Deproteinasi Cangkang Rajungan

Dalam penelitian ini telah dilakukan penelitian untuk mengetahui pengaruhpenambahan ion-ion logam di dalam media padat terhadap pertumbuhanbakteri protease, serta pengujian pengaruh konsentrasi substrat protein dalam media cair terhadap aktivitas proteolitik bakteri. Penambahan ion logam Mn, Co, Cu dan Zn ke dalam media padat telah mampu meningkatkan pertumbuhan bakteri protease yang ditunjukkan melalui peningkatan jumlah produksi enzim ekstraseluler disekitar tempat tumbuh isolat. Diantara ion-ion logam yang digunakan, ion Mn memberikan hasil yang sangat baik dibanding dengan ion-ion lainnya. Penambahan konsentrasi substrat protein pada media cair sebanyak 24%~40% telah mampu meningkatkan aktivitas protease bakteri, sedangkan penambahan 8%~16% substrat ini justru menghambat aktivitas bakter. Hasil penelitian ini diharapkan dapat menjadi dasar untuk mengoptimalkan proses pembuatan chitin dengan bahan baku limbah cangkang rajungan secara biologis, yang dipandang sebagai proses yang lebih ramah lingkungan dibandingkan dengan proses secara kimiawi

Pengolahan Lindi (Leachate) Dari Tpa Dengan Sistem Koagulasi - Biofilter Anaerobic

Leachate is the pollutant which contains various kinds of both organic such as some harmful photogenic bacteria\u27s and parasitic microbes like Sarcoptes sp and inorganic compounds such as ammonia. The leachate can be caused prurity to human skin. Base on data from Piyungan Community Health Centre, Microbes caused the incidence of dermatitis take number 4 from 10-disease rank within 75%. Piyungan Disposal Site has a possiblity to pollute to Opak River. the leachate need to be processed to decrease the MPN, COD, BOD, TSS and Ammonia parameters before it will be polluted of Opak River. The research had been done to process the leachate to decrease the MPN, COD, BOD, TSS and Ammonia parameters with use coagulation - biofilter anaerobic system. Equipment used was consisted of leachate equalisation (catcher) tank; alum and lime solution container; leachate coagulation tank and biofilter anaerobic tank. The research show that there were influence of leachate processing with coagulation and anaerobic biofilter toward the decreasing of MPN, COD, BOD, TSSand Ammonia parameters with 1, 2, and 3 hours detention time