Topological superconductors as nonrelativistic limits of Jackiw-Rossi and Jackiw-Rebbi models

We argue that the nonrelativistic Hamiltonian of p_x+ip_y superconductor in two dimensions can be derived from the relativistic Jackiw-Rossi model by taking the limit of large Zeeman magnetic field and chemical potential. In particular, the existence of a fermion zero mode bound to a vortex in the p_x+ip_y superconductor can be understood as a remnant of that in the Jackiw-Rossi model. In three dimensions, the nonrelativistic limit of the Jackiw-Rebbi model leads to a "p+is" superconductor in which spin-triplet p-wave and spin-singlet s-wave pairings coexist. The resulting Hamiltonian supports a fermion zero mode when the pairing gaps form a hedgehoglike structure. Our findings provide a unified view of fermion zero modes in relativistic (Dirac-type) and nonrelativistic (Schr\"odinger-type) superconductors.Comment: 7 pages, no figure; published versio

Isolated Flat Bands and Spin-1 Conical Bands in Two-Dimensional Lattices

Dispersionless bands, such as Landau levels, serve as a good starting point for obtaining interesting correlated states when interactions are added. With this motivation in mind, we study a variety of dispersionless ("flat") band structures that arise in tight-binding Hamiltonians defined on hexagonal and kagome lattices with staggered fluxes. The flat bands and their neighboring dispersing bands have several notable features: (a) Flat bands can be isolated from other bands by breaking time reversal symmetry, allowing for an extensive degeneracy when these bands are partially filled; (b) An isolated flat band corresponds to a critical point between regimes where the band is electron-like or hole-like, with an anomalous Hall conductance that changes sign across the transition; (c) When the gap between a flat band and two neighboring bands closes, the system is described by a single spin-1 conical-like spectrum, extending to higher angular momentum the spin-1/2 Dirac-like spectra in topological insulators and graphene; and (d) some configurations of parameters admit two isolated parallel flat bands, raising the possibility of exotic "heavy excitons"; (e) We find that the Chern number of the flat bands, in all instances that we study here, is zero.Comment: 7 pages. Sec. II slightly expanded. References adde

Algebraic characterization of anomalies in chiral WW_{3} gravity

The anomalies which occur in chiral WW_{3} gravity are characterized by solving the BRS consistency condition.Comment: 25 pages, report CBPF-NF-042/9

Teacher and Student Perspectives on Songwriting Pedagogy in Middle School

A song is a form of musical composition that involves a marriage between words and melody. In music education, songwriting often belongs to the sphere of popular music. Although songs are omnipresent in adolescents’ lives, less than 7% of the secondary schools in the United States offer songwriting. The present study focused on an after-school songwriting course in a middle school in the Southern U.S., a 21st-century learning environment where music and technology walked hand in hand, and adolescents composed, produced, and distributed original songs while finding their voices as songwriters. Five broad interrelated themes emerged from the literature review: songwriting is a place for inclusion, a music technology laboratory, it does not need traditional music notation, the teacher as facilitator, and conceptual teaching. The purpose of this study was to explore middle school songwriting pedagogy, how the teacher designed, implemented, and evaluated the songwriting course, and the students’ perspectives on their experiences. Ethnographic methods of data collection were employed, comprising interviews, field notes and participant observation, documents, and creative writing as research. Thematic and structural narrative analytical approaches suggested that teachers succeeded in forging a 21st-century popular music laboratory where students pursued their interests facilitated by a safe and collaborative environment in which teacher and peer feedback enriched trial-and-error in sound. Teachers’ strategies ranged from modeling to fading and the formulation of scaffolding where students interacted with music technology in a recording studio the size of their hands, resituating play at the center of music-making. Consequently, students learned from eliminating their mistakes and solving real-world musical problems that emerged from and within the processual products of their songwriting. The teacher described her pedagogic approach as focused on constant feedback, modeling, and scaffolding toward small projects that strengthened students’ musicianship. In her view, songwriting was personal. In addition, it offered the opportunity to pull students into large ensembles. Students expressed ease in using Digital Audio Workstations (DAWs) on tablet-based devices to facilitate music participation since most did not play a musical instrument. They believed songwriting enabled them to learn to collaborate, take risks, and improve their musical skills through constructive feedback

Dumping and Anti-Dumping in International Trade Origins, Legal Nature, and Evolution Developments in Brazil and in the United States

Dumping is when an exporting country sells their goods in the foreign market for less than the price of the goods in their own domestic market. Dumping has a negative connotation because it threatens domestic industries in the importing country. In response to harmful dumping situations, mechanisms of defense have been developed to protect nations from unfair trade practices. The General Agreement on Tariffs and Trade (GATT) recognizes in Article VI anti-dumping tariffs as a legitimate defense to protect domestic industries from foreign predatory pricing practices. This paper focuses on anti-dumping developments in international trade since the beginning of the 20th century until the creation of the World Trade Organization (WTO), and pays special attention to those in Brazil and the United States

Specific Measurement Of Tethered Running Kinetics And Its Relationship To Repeated Sprint Ability

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Repeated sprint ability has been widely studied by researchers, however, analysis of the relationship between most kinetic variables and the effect of fatigue is still an ongoing process. To search for the best biomechanical parameter to evaluate repeated sprint ability, several kinetic variables were measured in a tethered field running test and compared regarding their sensitivity to fatigue and correlation with time trials in a free running condition. Nine male sprint runners (best average times: 100 m = 10.45 +/- 0.07 s; 200 m = 21.36 +/- 0.17 s; 400 m = 47.35 +/- 1.09 s) completed two test sessions on a synthetic track. Each session consisted of six 35 m sprints interspersed by 10 s rest under tethered field running or free running conditions. Force, power, work, an impulse and a rate of force development were all directly measured using the sensors of a new tethered running apparatus, and a one-way ANOVA with Scheffe post-hoc test used to verify differences between sprints (p < 0.05). Pearson product-moment correlation measured the relationship between mechanical variables and free running performance. A total impulse, the rate of force development and maximum force did not show significant differences for most sprints. These three variables presented low to moderate correlations with free running performance (r between 0.01 and -0.35). Maximum and mean power presented the strongest correlations with free running performance (r = -0.71 and -0.76, respectively; p < 0.001), followed by mean force (r = -0.61; p < 0.001) and total work (r = -0.50; p < 0.001). It was concluded that under a severe work-to-rest ratio condition, power variables were better suited to evaluating repeated sprint ability than the other studied variables.491245256Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAEPEX [065/2011]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2009/08535-5, 2013/16710-7