Fire and Climax Spruce Forests in Central Yukon

Observations made during recent studies into fire history of forests in central Yukon ... suggest that, in the event of long-continued absence of fire, mixed stands of black and white spruce ... might become mono-specific black spruce stands. It is, however, unlikely that fires will often be absent for the long time periods needed for this change to develop. ..

Addition Spectra of Quantum Dots in Strong Magnetic Fields

We consider the magnetic field dependence of the chemical potential for parabolically confined quantum dots in a strong magnetic field. Approximate expressions based on the notion that the size of a dot is determined by a competition between confinement and interaction energies are shown to be consistent with exact diagonalization studies for small quantum dots. Fine structure is present in the magnetic field dependence which cannot be explained without a full many-body description and is associated with ground-state level crossings as a function of confinement strength or Zeeman interaction strength. Some of this fine structure is associated with precursors of the bulk incompressible states responsible for the fractional quantum Hall effect.Comment: 11 pages, 3 figures (available from [email protected]). Revtex 3.0. (IUCM93-010

Three sides to every story: Gender perspectives in energy transition pathways in Canada, Kenya and Spain

Transitions toward a low-carbon future are not only technical and economical, but also deeply social and gendered. The gendered nature of energy transitions is often implicit and unexplored. As a corrective, this paper explores energy pathways by applying concepts from innovations and gender studies. We examine gender perspectives and niche energy innovations which could disrupt the regime. The regime represents the mainstream pathway that includes the dominant gender perspective and energy system. We explore different gender perspectives of energy transition pathways by applying an Alternative Pathways framework that includes: (1) on-stream pathways that exist within the mainstream pathway to promote equal opportunities for women and men, as well as niches for energy innovations without challenging the high-carbon energy regime; (2) off-stream pathways that depart from the mainstream and promote differences across different genders while creating niches outside the energy regime; and (3) transformative pathways that are fundamentally different from the previous mainstream and includes all gender perspectives in a new energy regime. Applying this framing, in Canada, we explored Indigenous perspectives in the oil sands sector; in Kenya, we studied largescale renewable energy impacting Indigneous communities; in Spain, we evaluate the movement away from fossil fuels and towards renewable technologies. The framework helped to identify that mainstream pathways represented the dominant male perspective while woman's perspective were largely left out. Such absence generate energy pathways that are disconnected from local realities, lack public buy-in and slow-down a sustainable energy transition. © 2020 The Author(s)We would like to acknowledge the feedback of the two anonymous reviews as well as the TRANSrisk consortium members. We would also like to acknowledge the Maria de Maeztu excellence accreditation MDM-2017-0714 of BC3

Direct sums and the Szlenk index

For $\alpha$ an ordinal and $1<p<\infty$, we determine a necessary and sufficient condition for an $\ell_p$-direct sum of operators to have Szlenk index not exceeding $\omega^\alpha$. It follows from our results that the Szlenk index of an $\ell_p$-direct sum of operators is determined in a natural way by the behaviour of the $\epsilon$-Szlenk indices of its summands. Our methods give similar results for $c_0$-direct sums.Comment: The proof of Proposition~2.4 has changed, with some of the arguments transferred to the proof of an added-in lemma, Lemma~2.8. Changes have been made to the Applications sectio

Phase Transitions in Quantum Dots

We perform Hartree-Fock calculations to show that quantum dots (i.e. two dimensional systems of up to twenty interacting electrons in an external parabolic potential) undergo a gradual transition to a spin-polarized Wigner crystal with increasing magnetic field strength. The phase diagram and ground state energies have been determined. We tried to improve the ground state of the Wigner crystal by introducing a Jastrow ansatz for the wavefunction and performing a variational Monte Carlo calculation. The existence of so called magic numbers was also investigated. Finally, we also calculated the heat capacity associated with the rotational degree of freedom of deformed many-body states.Comment: 14 pages, 7 postscript figure

Ensemble density functional theory of the fractional quantum Hall effect

We develop an ensemble density functional theory for the fractional quantum Hall effect using a local density approximation. Model calculations for edge reconstructions of a spin-polarized quantum dot give results in good agreement with semiclassical and Hartree-Fock calculations, and with small system numerical diagonalizations. This establishes the usefulness of density functional theory to study the fractional quantum Hall effect, which opens up the possibility of studying inhomegeneous systems with many more electrons than has heretofore been possible.Comment: Improved discussion of ensemble density functional theory. 4 pages plus 3 postscript figures, uses latex with revtex. Contact [email protected]

Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation

We describe a D--brane inflation model which consists of two fractional D3 branes separated on a transverse $T^2 \times K3$. Inflation arises due to the resolved orbifold singularity of $K3$ which corresponds to an anomalous D--term on the brane. We show that D--brane inflation in the bulk corresponds to D--term inflation on the brane. The inflaton and the trigger field parametrize the interbrane distances on $T^2$ an $K3$ respectively. After inflation the branes reach a supersymmetric configuration in which they are at the origin of $T^2$ but separated along the $K3$ directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of 2\pi; v3: more minor correction

Cronin effect for protons and pions in pA collisions

Pions and protons production cross-sections are analyzed in proton-proton and proton-nucleus collisions at the RHIC energy at midrapidity. We employ the pQCD factorization scheme supplemented with the color-dipole formalism to investigate the Cronin effect. We calculate the broadening in the color-dipole approach for different centralities. Our main goal is to investigate, in a parameter-free manner within a unified framework, how much of the cronin effect for both pions and baryons comes from the transverse momentum broadening due to initial partons multi-scatterings. We conclude that final-state effects in pA collisions are important. Uncertainties in nuclear shadowing of various parton distributions and parton fragmentation functions are also discussed.Comment: 7 pages, 8 figure