Transient interference of transmission and incidence

Due to a transient quantum interference during a wavepacket collision with a potential barrier, a particular momentum, that depends on the potential parameters but is close to the initial average momentum, becomes suppressed. The hole left pushes the momentum distribution outwards leading to a significant constructive enhancement of lower and higher momenta. This is explained in the momentum complex-plane language in terms of a saddle point and two contiguous ``structural'' poles, which are not associated with resonances but with incident and transmitted components of the wavefunction.Comment: 4 pages of text, 6 postscript figures, revte

Stereodynamical Control of a Quantum Scattering Resonance in Cold Molecular Collisions

Cold collisions of light molecules are often dominated by a single partial wave resonance. For the rotational quenching of HD (v=1, j=2) by collisions with ground state para-H2, the process is dominated by a single L=2 partial wave resonance centered around 0.1 K. Here, we show that this resonance can be switched on or off simply by appropriate alignment of the HD rotational angular momentum relative to the initial velocity vector, thereby enabling complete control of the collision outcome

L'entrepreneuriat social, mieux connaître Ie concept

Entrepreneurship is a recognized concept both for research and practice. It is possible to find university courses, research published in specialized journals, associations dedicated to entrepreneurship promotion and governmental support. In a regional

Explicit solution for a Gaussian wave packet impinging on a square barrier

The collision of a quantum Gaussian wave packet with a square barrier is solved explicitly in terms of known functions. The obtained formula is suitable for performing fast calculations or asymptotic analysis. It also provides physical insight since the description of different regimes and collision phenomena typically requires only some of the terms.Comment: To be published in J. Phys.

Advice for New Authors about the Submission of Articles / Conseils pour les nouveaux auteurs sur la soumission d’articles

ABSTRACT New authors often see the publication process as a mystery that only gets revealed in bits and pieces over time. This article aims to present some tips and ideas to new authors to facilitate the submission of an article to Canadian Journal of Nonprofit and Social Economy Research / Revue canadienne de recherche sur les OSBL et l’économie sociale (ANSERJ). It describes the review process and highlights some key milestones. As the English Language and French Language editors for ANSERJ, we would like to encourage new contributors, and thus we will highlight specific items as they apply to ANSERJ. These guidelines complement the author guidelines already posted on the ANSERJ website. Our advice may apply to authors interested in other journals with a peer review process. RÉSUMÉ Les nouveaux auteurs considèrent souvent le processus de publication comme un mystère qui se découvre au fil du temps. Cet article vise à présenter certains conseils et réflexions pour faciliter la soumission d’un article à la Revue canadienne de recherche sur les OSBL et l’économie sociale / Canadian Journal of Nonprofit and Social Economy Research (ANSERJ). Il décrit le processus de publication et ses étapes principales. À titre de rédacteurs en chef d’ANSERJ, nous aimerions encourager les nouveaux chercheurs, contribuer au débat par quelques conseils et réflexions et souligner certains éléments spécifiques à notre revue. Les présentes réflexions complètent les directives déjà présentes sur le site web de la revue. Ils peuvent s’appliquer à des auteurs intéressés par d’autres revues avec comité de lecture

Time scale of forerunners in quantum tunneling

The forerunners preceding the main tunneling signal of the wave created by a source with a sharp onset or by a quantum shutter, have been generally associated with over-the-barrier (non-tunneling) components. We demonstrate that, while this association is true for distances which are larger than the penetration lenght, for smaller distances the forerunner is dominated by under-the-barrier components. We find that its characteristic arrival time is inversely proportional to the difference between the barrier energy and the incidence energy, a tunneling time scale different from both the phase time and the B\"uttiker-Landauer (BL) time.Comment: Revtex4, 14 eps figure

Tunneling dynamics in relativistic and nonrelativistic wave equations

We obtain the solution of a relativistic wave equation and compare it with the solution of the Schroedinger equation for a source with a sharp onset and excitation frequencies below cut-off. A scaling of position and time reduces to a single case all the (below cut-off) nonrelativistic solutions, but no such simplification holds for the relativistic equation, so that qualitatively different ``shallow'' and ``deep'' tunneling regimes may be identified relativistically. The nonrelativistic forerunner at a position beyond the penetration length of the asymptotic stationary wave does not tunnel; nevertheless, it arrives at the traversal (semiclassical or B\"uttiker-Landauer) time "tau". The corresponding relativistic forerunner is more complex: it oscillates due to the interference between two saddle point contributions, and may be characterized by two times for the arrival of the maxima of lower and upper envelops. There is in addition an earlier relativistic forerunner, right after the causal front, which does tunnel. Within the penetration length, tunneling is more robust for the precursors of the relativistic equation

Fundraising Methods: Past, Present, Future

The term ‘fundraising methods’ refers to the tactics used by charities to generate current or future monies and gifts in kind to provide services to clients, fund research, and cover administrative costs. Under conditions of reduced financial support from government, fundraising is an important, even critical, source of revenue for charities. Equally important is access to accurate information on fundraising methods used by charities in Canada. This paper traces the evolution of fundraising data collected by Canada Revenue Agency (CRA) over the last ten years, compares definitions employed by CRA with examples drawn from the academic and practitioner literatures, and highlights methods not currently being tracked by the T3010 Registered Charity Information Return

Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems

Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests