Texture control in a pseudospin Bose-Einstein condensate

We describe a wavefunction engineering approach to the formation of textures in a two-component nonrotated Bose-Einstein condensate. By controlling the phases of wavepackets that combine in a three-wave interference process, a ballistically-expanding regular lattice-texture is generated, in which the phases determine the component textures. A particular example is presented of a lattice-texture composed of half-quantum vortices and spin-2 textures. We demonstrate the lattice formation with numerical simulations of a viable experiment, identifying the textures and relating their locations to a linear theory of wavepacket interference.Comment: 4 pages, 5 figures, REVTeX4-

Phase vortices from a Young's three-pinhole interferometer

An analysis is presented of the phase vortices generated in the far field, by an arbitrary arrangement of three monochromatic point sources of complex spherical waves. In contrast with the case of three interfering plane waves, in which an infinitely-extended vortex lattice is generated, the spherical sources generate a finite number of phase vortices. Analytical expressions for the vortex core locations are developed and shown to have a convenient representation in a discrete parameter space. Our analysis may be mapped onto the case of a coherently-illuminated Young's interferometer, in which the screen is punctured by three rather than two pinholes.Comment: 10 pages, 8 figures, REVTeX4, Submitted to Phys. Rev.

Tectonics, eustacy and climate: foraminifera and the late Cenozoic evolution of North-Central Chile

Abstrac

International Space Station Active Thermal Control Sub-System On-Orbit Pump Performance and Reliability Using Liquid Ammonia as a Coolant

The International Space Station (ISS) contains two Active Thermal Control Sub-systems (ATCS) that function by using a liquid ammonia cooling system collecting waste heat and rejecting it using radiators. These subsystems consist of a number of heat exchangers, cold plates, radiators, the Pump and Flow Control Subassembly (PFCS), and the Pump Module (PM), all of which are Orbital Replaceable Units (ORU's). The PFCS provides the motive force to circulate the ammonia coolant in the Photovoltaic Thermal Control Subsystem (PVTCS) and has been in operation since December, 2000. The Pump Module (PM) circulates liquid ammonia coolant within the External Active Thermal Control Subsystem (EATCS) cooling the ISS internal coolant (water) loops collecting waste heat and rejecting it through the ISS radiators. These PM loops have been in operation since December, 2006. This paper will discuss the original reliability analysis approach of the PFCS and Pump Module, comparing them against the current operational performance data for the ISS External Thermal Control Loops

Vortex-lattice formation and melting in a nonrotating Bose-Einstein condensate

Numerical simulations of the interference of a three-way segmented nonrotating Bose-Einstein condensate reveal the production of a honeycomb vortex lattice containing significant numbers of vortices and antivortices. If confined within a trap, the lattice subsequently melts, exhibiting a rich assortment of vortex-antivortex interactions. In contrast with nonlinear vortex production mechanisms previously described for Bose-Einstein condensates, the process here is shown to be primarily one of linear superposition, with initial vortex locations approximately described by a linear theory of wave packet interference.Comment: 10 pages, 8 figures, REVTeX4, Added a section following the introduction and clarified the description of the numerical model. Added reference

Relationship between lexical frequency and vocabulary acquisition: how to acquire a language

ABSTRACT Vocabulary acquisition and language learning are very dynamic process in which many factors are in play. One of these is lexical frequency, which refers to how much frequently a word is uttered in a language. As such, it can be said that the more a word is present in a language, the easier it is to be acquired. In this study, we tried to find the relationship between lexical frequency and vocabulary acquisition in the process of learning a first and second language. The results of this study showed that there is indeed a relation between how frequently a word is used in a language and how quickly it is learned. Consequently, focusing on frequently used vocabulary might aid in the process of learning a language. However, it was found that it is difficult to choose a reliable frequency list that would give an accurate picture of a language. Frequency lists might vary depending on the context, although most still resemble each other in content. Additionally, although it has been demonstrated that frequency plays a big role in language learning, foreign language instruction has yet to catch up with lexical frequency in the classroom. KEYWORDS: Lexicon; Lexical competence; vocabulary; foreign language. Relación entre el léxico y la adquisición de vocabulario: cómo adquirir un idioma RESUMEN La adquisición de vocabulario y el aprendizaje de idiomas son procesos muy dinámicos en los que intervienen muchos factores. Uno de ellos es la frecuencia léxica, que se refiere a la frecuencia con que se pronuncia una palabra en un idioma. Así pues, puede decirse que cuanto más presente esté una palabra en un idioma, más fácil será su adquisición. En el presente estudio se ha tratado de encontrar la relación entre la frecuencia léxica y la adquisición de vocabulario en el proceso de aprendizaje de un primer y un segundo idioma. Los resultados de este estudio demostraron que existe efectivamente una relación entre la frecuencia con que se utiliza una palabra en un idioma y la rapidez con que se aprende. Por consiguiente, centrarse en el vocabulario de uso frecuente podría ayudar en el proceso de aprendizaje de un idioma. Sin embargo, se comprobó que es difícil elegir una lista de frecuencias fiable que dé una imagen exacta de un idioma. Las listas de frecuencias pueden variar según el contexto, aunque la mayoría de ellas siguen pareciéndose entre sí en cuanto a su contenido. Además, aunque se ha demostrado que la frecuencia desempeña un papel importante en el aprendizaje de idiomas, la enseñanza de idiomas extranjeros todavía no ha alcanzado la frecuencia léxica en el aula. PALABRAS CLAVE: Léxico; competencia léxica; vocabulario; idioma extranjer

Bayesian Forecasting in Economics and Finance: A Modern Review

The Bayesian statistical paradigm provides a principled and coherent approach to probabilistic forecasting. Uncertainty about all unknowns that characterize any forecasting problem -- model, parameters, latent states -- is able to be quantified explicitly, and factored into the forecast distribution via the process of integration or averaging. Allied with the elegance of the method, Bayesian forecasting is now underpinned by the burgeoning field of Bayesian computation, which enables Bayesian forecasts to be produced for virtually any problem, no matter how large, or complex. The current state of play in Bayesian forecasting in economics and finance is the subject of this review. The aim is to provide the reader with an overview of modern approaches to the field, set in some historical context; and with sufficient computational detail given to assist the reader with implementation.Comment: The paper is now published online at: https://doi.org/10.1016/j.ijforecast.2023.05.00