Aquilegia, Vol. 28 No. 3, May-June-July 2004: Newsletter of the Colorado Native Plant Society

https://epublications.regis.edu/aquilegia/1102/thumbnail.jp

Statistical Theory for Incoherent Light Propagation in Nonlinear Media

A novel statistical approach based on the Wigner transform is proposed for the description of partially incoherent optical wave dynamics in nonlinear media. An evolution equation for the Wigner transform is derived from a nonlinear Schrodinger equation with arbitrary nonlinearity. It is shown that random phase fluctuations of an incoherent plane wave lead to a Landau-like damping effect, which can stabilize the modulational instability. In the limit of the geometrical optics approximation, incoherent, localized, and stationary wave-fields are shown to exist for a wide class of nonlinear media.Comment: 4 pages, REVTeX4. Submitted to Physical Review E. Revised manuscrip

Quantum Multibaker Maps: Extreme Quantum Regime

We introduce a family of models for quantum mechanical, one-dimensional random walks, called quantum multibaker maps (QMB). These are Weyl quantizations of the classical multibaker models previously considered by Gaspard, Tasaki and others. Depending on the properties of the phases parametrizing the quantization, we consider only two classes of the QMB maps: uniform and random. Uniform QMB maps are characterized by phases which are the same in every unit cell of the multibaker chain. Random QMB maps have phases that vary randomly from unit cell to unit cell. The eigenstates in the former case are extended while in the latter they are localized. In the uniform case and for large $\hbar$, analytic solutions can be obtained for the time dependent quantum states for periodic chains and for open chains with absorbing boundary conditions. Steady state solutions and the properties of the relaxation to a steady state for a uniform QMB chain in contact with ``particle'' reservoirs can also be described analytically. The analytical results are consistent with, and confirmed by, results obtained from numerical methods. We report here results for the deep quantum regime (large $\hbar$) of the uniform QMB, as well as some results for the random QMB. We leave the moderate and small $\hbar$ results as well as further consideration of the other versions of the QMB for further publications.Comment: 17 pages, referee's and editor's comments addresse

Localization by disorder in the infrared conductivity of (Y,Pr)Ba2Cu3O7 films

The ab-plane reflectivity of (Y{1-x}Prx)Ba2Cu3O7 thin films was measured in the 30-30000 cm-1 range for samples with x = 0 (Tc = 90 K), x = 0.4 (Tc = 35 K) and x = 0.5 (Tc = 19 K) as a function of temperature in the normal state. The effective charge density obtained from the integrated spectral weight decreases with increasing x. The variation is consistent with the higher dc resistivity for x = 0.4, but is one order of magnitude smaller than what would be expected for x = 0.5. In the latter sample, the conductivity is dominated at all temperatures by a large localization peak. Its magnitude increases as the temperature decreases. We relate this peak to the dc resistivity enhancement. A simple localization-by-disorder model accounts for the optical conductivity of the x = 0.5 sample.Comment: 7 pages with (4) figures include

Anthropogenic alteration of nutrient supply increases the global freshwater carbon sink

Lakes have a disproportionate effect on the global carbon (C) cycle relative to their area, mediating C transfer from land to atmosphere, and burying organic-C in their sediments. The magnitude and temporal variability of C burial is, however, poorly constrained, and the degree to which humans have influenced lake C cycling through landscape alteration has not been systematically assessed. Here, we report global and biome specific trajectories of lake C sequestration based on 516 lakes and show that some lake C burial rates (i.e., those in tropical forest and grassland biomes) have quadrupled over the last 100 years. Global lake C-sequestration (~0.12 Pg year-1) has increased by ~72 Tg year-1 since 1900, offsetting 20% of annual CO2 freshwater emissions rising to ~30% if reservoirs are included and contributing to the residual continental C sink. Nutrient availability explains ~70% of the observed increase, while rising temperatures have a minimal effect

Reflecting back and forwards: The ebb and flow of peer-reviewed reflective practice research in sport

Researchers in sport have claimed that reflective practice is important for competent practice. Evidence supporting this claim is sparse, highly theoretical and located within a variety of domains. The aim of this study was to assimilate and analyse the last 12 years of reflective practice literature within the sport domain in order to identify new areas of inquiry, emerging trends with regard to findings or methodology, and to identify implications for future research and practice. A sample of 68 papers published between 2001 and 2012 was examined, and investigated for the research locations, data collection methods utilised, and the professions and communities involved. The paper concludes with some suggestions for future research

Young and Intermediate-age Distance Indicators

Distance measurements beyond geometrical and semi-geometrical methods, rely mainly on standard candles. As the name suggests, these objects have known luminosities by virtue of their intrinsic proprieties and play a major role in our understanding of modern cosmology. The main caveats associated with standard candles are their absolute calibration, contamination of the sample from other sources and systematic uncertainties. The absolute calibration mainly depends on their chemical composition and age. To understand the impact of these effects on the distance scale, it is essential to develop methods based on different sample of standard candles. Here we review the fundamental properties of young and intermediate-age distance indicators such as Cepheids, Mira variables and Red Clump stars and the recent developments in their application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in Space Science Reviews (Chapter 3 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

The polyanalytic Ginibre ensembles

We consider a polyanalytic generalization of the Ginibre ensemble. This models allowing higher Landau levels (the Ginibre ensemble corresponds to the lowest Landau level). We study the local behavior of this point process under blow-ups.Comment: 31 page

Divided communities and contested landscapes: Mobility, development and shifting identities in migrant destination sites in Papua New Guinea

Internal conflicts at the local and national levels in several South Pacific countries have revealed the fragility of national unity and the difficulties nations face in governing and managing their own economic development. In Papua New Guinea, the focus of this paper, an uncertain economic future for many rural and urban communities, and rising inequalities in income opportunities and access to resources, have coincided with greater intolerance of migrants at sites of high in-migration by customary landowners and provincial and local authorities. This paper draws on fieldwork undertaken in the major oil palm growing regions of Papua New Guinea where migrants from densely populated regions of the country have settled on state land alienated from customary landowners. We examine how struggles over land, resource control and development are polarising migrant and landowner identities resulting in increasing tensions and episodic communal violence. A settler identity is emerging based on a narrative of nation building and national development, while an ethno-regional identity amongst customary landowners is undermining the citizen rights of migrants and challenging the role and authority of the state in land matters