Coherent instabilities of intense high-energy "white" charged-particle beams in the presence of nonlocal effects within the context of the Madelung fluid description

A hydrodynamical description of coherent instabilities that take place in the longitudinal dynamics of a charged-particle coasting beam in a high-energy accelerating machine is presented. This is done in the framework of the Madelung fluid picture provided by the Thermal Wave Model. The well known coherent instability charts in the complex plane of the longitudinal coupling impedance for monochromatic beams are recovered. The results are also interpreted in terms of the deterministic approach to modulational instability analysis usually given for monochromatic large amplitude wave train propagation governed by the nonlinear Schr\"odinger equation. The instability analysis is then extended to a non-monochromatic coasting beam with a given thermal equilibrium distribution, thought as a statistical ensemble of monochromatic incoherent coasting beams ("white" beam). In this hydrodynamical framework, the phenomenon of Landau damping is predicted without using any kinetic equation governing the phase space evolution of the system.Comment: 14 pages, 1 figur

„Uparte trwanie baroku” w recepcji wierszy Stanisława Barańczaka

The article focuses on the functioning of the term ‘baroque’ in the reception of Stanisław Barańczak’s poems. The author takes into account the context of fashion for returning to the legacy of the baroque which became visible after 1956 in both poetry itself and in the discourse of both literary criticism and literary studies

Evaluating Ecosystem Investments

This report focuses on what was learned about best practices for evaluating the effects of ecosystem investments along with examples of how others are using these practicesin their work.MethodologyThree research questions guided this engagement:What are the new / best practices in evaluating the effects of ecosystem invest­ments?Which organizations are evaluating these investments well? What can they teach us?What relevant outcomes and indicators could Omidyar Network use to evaluate its ecosystem investments?To answer these questions, FSG conducted the following activities, in addition to drawing on our experience supporting strategic learning and evaluation in complex environments. Appendix A includes a complete list of grants reviewed and interviewees.Grants analysis: FSG analyzed Omidyar Network's Initiative Results Architecture frameworks and 23 grants within its ecosystem investment portfolio. These docu­ments helped ground our research in an understanding of the different types of ecosystem investments Omidyar Network is making, as well as how the organiza­tion currently evaluates the impact of its ecosystem investments.Literature review: FSG reviewed more than 60 publications to identify best practices in evaluating ecosystem investments—these publications included both peer-reviewed journal articles and "grey literature" (conference presentations, blog posts) by organizations employing advocacy-type strategies.Interviews: FSG conducted interviews with nine external experts (listed in Appen­dix A) to more deeply understand effective practices in evaluating the effects of eco­system investments and to identify leading organizations in this area. Interviewees were identified to glean best practices from both within and outside the traditional social sector

New features of modulational instability of partially coherent light; importance of the incoherence spectrum

It is shown that the properties of the modulational instability of partially coherent waves propagating in a nonlinear Kerr medium depend crucially on the profile of the incoherent field spectrum. Under certain conditions, the incoherence may even enhance, rather than suppress, the instability. In particular, it is found that the range of modulationally unstable wave numbers does not necessarily decrease monotonously with increasing degree of incoherence and that the modulational instability may still exist even when long wavelength perturbations are stable.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let

Generalized dressing method for nonlinear evolution equations describing partially coherent wave propagation in noninstantaneous Kerr media

A generalized dressing method is presented for integration of the nonlinear evolution equation of the coherent density function describing partially coherent wave propagation in a noninstantaneous Kerr media. As an example an exact, partially coherent multisource N-soliton solution is derived. It is also demonstrated how this method is applicable for construction of solutions to the equivalent coupled system of nonlinear Schrodinger equations of the self-consistent multimode theory

Landau damping of partially incoherent Langmuir waves

It is shown that partial incoherence, in the form of stochastic phase noise, of a Langmuir wave in an unmagnetized plasma gives rise to a Landau-type damping. Starting from the Zakharov equations, which describe the nonlinear interaction between Langmuir and ion-acoustic waves, a kinetic equation is derived for the plasmons by introducing the Wigner-Moyal transform of the complex Langmuir wave field. This equation is then used to analyze the stability properties of small perturbations on a stationary solution consisting of a constant amplitude wave with stochastic phase noise. The concomitant dispersion relation exhibits the phenomenon of Landau-like damping. However, this damping differs from the classical Landau damping in which a Langmuir wave, interacting with the plasma electrons, loses energy. In the present process, the damping is non-dissipative and is caused by the resonant interaction between an instantaneously-produced disturbance, due to the parametric interactions, and a partially incoherent Langmuir wave, which can be considered as a quasi-particle composed of an ensemble of partially incoherent plasmons.Comment: 12 page

Integrability and Conservation Laws for the Nonlinear Evolution Equations of Partially Coherent Waves in Noninstantaneous Kerr Media

It is shown that the evolution equations describing partially coherent wave propagation in noninstantaneous Kerr media are integrable and have an infinite number of invariants. A recursion relation for generating these invariants is presented, and it is demonstrated how to express them in the coherent density, self-consistent multimode, mutual coherence, and Wigner formalisms

Multi--hump soliton--like structures in interactions of lasers and Bose--Einstein condensates

An investigation is made of multi-hump and periodic solutions of the semi-classical coupled equations describing laser radiation copropagating with a Bose-Einstein condensate. Solutions reminiscent of optical vector solitons have been found and have been used to gain understanding of the dynamics observed in the numerical simulations, in particular to shed light on the phenomenon of jet emission from a condensate interacting with a laser.Comment: 6 pages, 4 figures; submitted to European Physics Letter