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

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

Pengaruh Lama Cuti Bersalin Terhadap Kelangsungan Pemberian ASI

Latar Belakang : Bekerja merupakan halangan terbesar dalam pemberian ASI. Pemerintah telah memberikan kebijakan cuti bersalin selama 2 bulan sebagai solusi, namun kelangsungan pemberian ASI di Indonesia tetap rendah. Perpanjangan cuti bersalin dipandang dapat mengatasi hal ini. Penelitian untuk membuktikan lama cuti bersalin yang lebih panjang dapat meningkatkan kelangsungan pemberian ASI, perlu dilakukan, sehingga dapat dijadikan pertimbangan kebijakan pemerintah selanjutnya.Metode : Observasional analitik dengan desain penelitian kohort-prospektif, dilanjutkan kajian kualitatif pada 32 ibu bekerja yang baru melahirkan < 1 bulan dan mendapat cuti bersalin. Analisis data dengan uji Chi-Square dan uji Fisher.Hasil : Persentase ibu yang masih memberi ASI pada kelompok lama cuti bersalin < 2 bulan dan > 2 bulan adalah 100% dan 93,75% (Uji Fisher, p=1,000) baik pada bulan pertama maupun kedua. Sebanyak 6,25% (1 orang) sudah tidak memberi ASI akibat kelainan anatomis pada payudara ibu, sehingga merupakan pengecualian. Sedangkan berdasar pola pemberian ASI nya, 43,75% dan 56,25% (Uji Chi-Square, p=0,480) memberi ASI eksklusif pada bulan pertama, menjadi 31,25% dan 50% (Uji Chi-Square, p=0,280) pada bulan kedua. Hasil kajian kualitatif didapatkan penyebab utama kegagalan pemberian ASI eksklusif adalah persepsi ibu bahwa produksi ASI nya kurang (63,16%).Simpulan : Pada kedua kelompok, kelangsungan pemberian ASI nya tidak berbeda, semuanya masih memberikan ASI. Namun pada kelompok lama cuti bersalin yang lebih panjang, lebih banyak ibu dengan kelangsungan pemberian ASI eksklusif sekalipun hal ini tidak bermakna secara statistik

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

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,

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,