Self-bound droplet of Bose and Fermi atoms in one dimension: Collective properties in mean-field and Tonks-Girardeau regimes

We investigate a dilute mixture of bosons and spin-polarized fermions in one dimension. With an attractive Bose-Fermi scattering length the ground state is a self-bound droplet, i.e., a Bose-Fermi bright soliton where the Bose and Fermi clouds are superimposed. We find that the quantum fluctuations stabilize the Bose-Fermi soliton such that the one-dimensional bright soliton exists for any finite attractive Bose-Fermi scattering length. We study density profile and collective excitations of the atomic bright soliton showing that they depend on the bosonic regime involved: mean-field or Tonks-Girardeau.

DIFFERENT MEDIA, DIFFERENT TYPES OF COLLECTIVE WORK IN ONLINE CONTINUING TEACHER EDUCATION: WOULD YOU PASS THE PEN, PLEASE?

This paper presents some findings regarding the interaction between different computer interfaces and different types of collective work. We want to claim that design in online learning environments has a paramount role in the type of collaboration that happens among participants. In this paper, we report on data that illustrate how teachers can collaborate online in order to learn how to use geometry software in teaching activities. A virtual environment which allows that construction to be carried out collectively, even if the participants are not sharing a classroom, is the setting for the research presented in this paper.

Collective scattering of massive stars in higher order gravity

In the weak field approximation of higher order gravity theory a gravitational potential is described by a Newtonian plus a Yukawa-like term. This new term is used to explain some aspects of galactic dynamics, without considering dark matter. Its presence modifies the scattering probability of a massive intruder star and relaxation time of the stellar system.

Stabilizing an attractive Bose-Einstein condensate by driving a surface collective mode

Bose-Einstein condensates with attractive interatomic interactions undergo collective collapse beyond a critical number. We show theoretically that if the low-lying collective modes of the condensate are excited, the radial breathing mode further destabilizes the condensate. Remarkably, excitation of the quadrupolar surface mode causes the condensate to become more stable, imparting quasiangular momentum to it. A significantly larger number of atoms may then occupy the condensate. Efforts are under way for the experimental realization of these effects. ©2001 The American Physical Society.

Social Panorama of Latin America 2006

Includes bibliography

The responsibility of financial actors

Includes bibliography

Fostering economic policy coordination in Latin America: the REDIMA approach to escaping the prisoner's dilemma

Includes bibliography

¿A Chilean wine cluster? governance and upgrading in the phase of internationalization

Includes bibliography

The collective memory and challenges of feminism

Includes bibliography

The social actors and development options

Analiza las ideas de don Jose Medina Echavarria acerca de las clases sociales, tanto de las dominantes como de las dominadas, que representan roles en el desarrollo de America Latina.

The social actors and structural adjustment

Includes bibliography

Three forms of social coordination

Includes bibliography

Indigenous organizations: rising actors in Latin America

Includes bibliography

Building community social capital

Includes bibliography