Manifestation of superfluidity in an evolving Bose-condensed gas

We study the generation of excitations due to an ''impurity''(static perturbation) placed into an oscillating Bose-condensed gas in the time-dependent trapping field. It is shown that there are two regions for the position of the local perturbation. In the first region the condensate flows around the ''impurity'' without generation of excitations demonstrating superfluid properties. In the second region the creation of excitations occurs, at least within a limited time interval, revealing destruction of superfluidity. The phenomenon can be studied by measuring the damping of condensate oscillations at different positions of the ''impurity''

A priori mixing of mesons and the |Delta I|=1/2 rule in K\to\pi\pi

We consider the hypothesis of a priori mixings in the mass eigenstates of mesons to obtain the |Delta I|=1/2 rule in K\to\pi\pi. The Hamiltonian responsible for the transition is the strong interacting one. The experimental data are described using the isospin symmetry relations between the strong coupling constants

Spatial Correlation Functions of one-dimensional Bose gases at Equilibrium

The dependence of the three lowest order spatial correlation functions of a harmonically confined Bose gas on temperature and interaction strength is presented at equilibrium. Our analysis is based on a stochastic Langevin equation for the order parameter of a weakly-interacting gas. Comparison of the predicted first order correlation functions to those of appropriate mean field theories demonstrates the potentially crucial role of density fluctuations on the equilibrium coherence length. Furthermore,the change in both coherence length and shape of the correlation function, from gaussian to exponential, with increasing temperature is quantified. Moreover, the presented results for higher order correlation functions are shown to be in agreeement with existing predictions. Appropriate consideration of density-density correlations is shown to facilitate a precise determination of quasi-condensate density profiles, providing an alternative approach to the bimodal density fits typically used experimentally

Properties of Foreshocks and Aftershocks of the Non-Conservative SOC Olami-Feder-Christensen Model: Triggered or Critical Earthquakes?

Following Hergarten and Neugebauer [2002] who discovered aftershock and foreshock sequences in the Olami-Feder-Christensen (OFC) discrete block-spring earthquake model, we investigate to what degree the simple toppling mechanism of this model is sufficient to account for the properties of earthquake clustering in time and space. Our main finding is that synthetic catalogs generated by the OFC model share practically all properties of real seismicity at a qualitative level, with however significant quantitative differences. We find that OFC catalogs can be in large part described by the concept of triggered seismicity but the properties of foreshocks depend on the mainshock magnitude, in qualitative agreement with the critical earthquake model and in disagreement with simple models of triggered seismicity such as the Epidemic Type Aftershock Sequence (ETAS) model [Ogata, 1988]. Many other features of OFC catalogs can be reproduced with the ETAS model with a weaker clustering than real seismicity, i.e. for a very small average number of triggered earthquakes of first generation per mother-earthquake.Comment: revtex, 19 pages, 8 eps figure

Intermittent implosion and pattern formation of trapped Bose-Einstein condensates with attractive interaction

The collapsing dynamics of a trapped Bose-Einstein condensate (BEC) with attractive interaction are revealed to exhibit two previously unknown phenomena. During the collapse, BEC undergoes a series of rapid implosions that occur {\it intermittently} within a very small region. When the sign of the interaction is suddenly switched from repulsive to attractive, e.g., by the Feshbach resonance, density fluctuations grow to form various patterns such as a shell structure.Comment: 5 pages, 2 figures, RevTeX, epsf.sty, corrected loss rate

The visibility of environmental rights in the EU legal order: eurolegalism in action?

The current article responds to a key puzzle and a question. First, why, given the potential for ‘rights talk’ that has been seen in other countries and other policy areas, have environmental rights in the EU legal order been relatively invisible until recently? And second, with Daniel Kelemen’s influential work on Eurolegalism arguing that the EU has become much more reliant on US-style adversarial legalism, including a shift towards rights-based litigation, do EU environmental rights fit the picture Kelemen has painted, or are they an exception? The article explores the visibility of EU environmental rights at EU level and then seeks to explain the possible reasons for visibility/invisibility

Evolution and global collapse of trapped Bose condensates under variations of the scattering length

We develop the idea of selectively manipulating the condensate in a trapped Bose-condensed gas, without perturbing the thermal cloud. The idea is based on the possibility to modify the mean field interaction between atoms (scattering length) by nearly resonant incident light or by spatially uniform change of the trapping magnetic field. For the gas in the Thomas-Fermi regime we find analytical scaling solutions for the condensate wavefunction evolving under arbitrary variations of the scattering length $a$. The change of $a$ from positive to negative induces a global collapse of the condensate, and the final stages of the collapse will be governed by intrinsic decay processes.Comment: 4 pages, LaTeX, other comments are at http://WWW.amolf.nl/departments/quantumgassen/TITLE.HTM

Critical temperature and Ginzburg-Landau equation for a trapped Fermi gas

We discuss a superfluid phase transition in a trapped neutral-atom Fermi gas. We consider the case where the critical temperature greatly exceeds the spacing between the trap levels and derive the corresponding Ginzburg-Landau equation. The latter turns out to be analogous to the equation for the condensate wave function in a trapped Bose gas. The analysis of its solution provides us with the value of the critical temperature $T_{c}$ and with the spatial and temperature dependence of the order parameter in the vicinity of the phase transition point.Comment: 6 pages, 1 figure, REVTeX. The figure improved. Misprints corrected. More discussion adde

Feminist composite narratives of Chinese women: the interrelationship of work, family and community in forced labour situations

This contribution builds on the work Lewis has engaged in around women’s decision-making processes on work and care. Gender has been an important consideration across her work and this has been explored in familial and organisational settings. The personal is undoubtedly political and a feminist lens privileges this. Previous research (including Lewis) has marked a shift from work-life balance to work personal life integration. This implies agency and perhaps a particular kind of woman able to make choices. In contrast, this paper focuses on Chinese migrant women working in vulnerable situations. Drawing on data gathered from a forced labour project, we present some composite narratives from women as daughters, mothers and wives. These highlight the role of the core economy in decisions about migration for work. Inevitably work decisions are bound up with and situated in wider care and familial networks. These insights around emotional and practical labour are feminist concerns. We present the complex decisions made by women around precarious work, present and distant ‘families’ and care. We suggest that future work-life research should heed Lewis’ call for more nuanced understandings of the multi-layered context of people’s experiences, workplace practices and relevant national policies, but go beyond this, to pay attention to the globalised forces underpinning ever greater inequity in work, in families and in communities