A Scalar Wigner Theory for Polarized Light in Nonlinear Kerr Media

A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr media and an extended phase space evolution equation is derived along with invariant quantities. We further consider modulation instability as well as the extension to partially coherent fields.Comment: 6 page

Soil carbon and nutrient accumulation under forest plantations in southern Rwanda

Tree and soil interactions may result in changes in soil carbon and nutrient contents. Forest plantations made up of monodominant stands of 17 different species, some native and some exotic to Rwanda, as well as a stand with mixed native tree species were investigated. Biosequential sampling was used followed by basic soil chemical analyses. Results revealed that the plantation species composition influenced the soil chemical properties. Total soil C and N, C: N ratio, available P, pH, and cation exchange capacity (CEC) differed significantly between plantation stands of different species (P < 0.001, N = 54). Increases in the levels of soil C, total N, CEC and base saturation (BS) were observed mainly in mixed native species (MNS), Polyscia fulva, Casuarina equisetifolia and Eucalyptus saligna. The pH declined slightly in soil beneath some Eucalyptus species treatments and increased in others. The high nutrient uptake by fast-growing trees and the acidic parent material were involved in the acidification process. The findings suggest that the species used in afforestation maintain soil fertility and protect the environment. It is recommended that afforestation of abandoned and less productive lands in Rwanda should utilize fast growing Eucalyptus species in combination with agroforestry and native species in order to maintain or improve soil chemical properties.Key words: Afforestation, base saturation (BS), cation exchange capacity (CEC), forest plantation, soil carbon, total N, Rwanda

Localized Flux Lines and the Bose Glass

Columnar defects provide effective pinning centers for magnetic flux lines in high--$T_{\rm c}$ superconductors. Utilizing a mapping of the statistical mechanics of directed lines to the quantum mechanics of two--dimensional bosons, one expects an entangled flux liquid phase at high temperatures, separated by a second--order localization transition from a low--temperature ``Bose glass'' phase with infinite tilt modulus. Recent decoration experiments have demonstrated that below the matching field the repulsive forces between the vortices may be sufficiently large to produce strong spatial correlations in the Bose glass. This is confirmed by numerical simulations, and a remarkably wide soft ``Coulomb gap'' at the chemical potential is found in the distribution of pinning energies. At low currents, the dominant transport mechanism in the Bose glass phase proceeds via the formation of double kinks between not necessarily adjacent columnar pins, similar to variable--range hopping in disordered semiconductors. The strong correlation effects originating in the long--range vortex interactions drastically reduce variable--range hopping transport.Comment: 10 pages, latex ("lamuphys.sty" file included), 6 figures can be obtained from the author ([email protected]); to appear in Proc. XIV Sitges conference on "Complex Behaviour of Glassy Systems" (Springer--Verlag

Civil Forfeiture and the Eighth Amendment After \u3cem\u3eAustin\u3c/em\u3e

Imagine owning an expensive piece of property, a piece of real estate perhaps, or maybe a car or boat. Now imagine having your property forcefully taken away from you because someone suspects, or pretends to suspect, that you are using the property in the commission of criminal acts. Then, imagine having to hire a lawyer and start a lawsuit to recover your property. After spending a small fortune in legal fees to recover your own property, imagine you lose your lawsuit, not because you could not prove your rightful ownership before its forceful seizure, but because you could not prove that the person who seized the property lacked a reasonable suspicion that you were using the property in the commission of criminal acts or that you were not in fact using the property in the commission of criminal acts. Finally, imagine that your only recourse is buying your property back from the person who took it. Not likely to happen in America? Think again. It might not be likely to happen in America if a private party forcefully seized your property. But if your own government took it, you are in deep trouble. This is, in fact, what is happening all over America thanks to 21 U.S.C. § 881 (Section 881), the civil forfeiture statute, and other state and federal forfeiture provision

Civil Forfeiture and the Eighth Amendment After \u3cem\u3eAustin\u3c/em\u3e

Imagine owning an expensive piece of property, a piece of real estate perhaps, or maybe a car or boat. Now imagine having your property forcefully taken away from you because someone suspects, or pretends to suspect, that you are using the property in the commission of criminal acts. Then, imagine having to hire a lawyer and start a lawsuit to recover your property. After spending a small fortune in legal fees to recover your own property, imagine you lose your lawsuit, not because you could not prove your rightful ownership before its forceful seizure, but because you could not prove that the person who seized the property lacked a reasonable suspicion that you were using the property in the commission of criminal acts or that you were not in fact using the property in the commission of criminal acts. Finally, imagine that your only recourse is buying your property back from the person who took it. Not likely to happen in America? Think again. It might not be likely to happen in America if a private party forcefully seized your property. But if your own government took it, you are in deep trouble. This is, in fact, what is happening all over America thanks to 21 U.S.C. § 881 (Section 881), the civil forfeiture statute, and other state and federal forfeiture provision

Carrots and Rainbows: Motivation and Social Practice in Open Source Software Development

Open source software (OSS) is a social and economic phenomenon that raises fundamental questions about the motivations of contributors to information systems development. Some developers are unpaid volunteers who seek to solve their own technical problems, while others create OSS as part of their employment contract. For the past 10 years, a substantial amount of academic work has theorized about and empirically examined developer motivations. We review this work and suggest considering motivation in terms of the values of the social practice in which developers participate. Based on the social philosophy of Alasdair MacIntyre, we construct a theoretical framework that expands our assumptions about individual motivation to include the idea of a long-term, value-informed quest beyond short-term rewards. This motivation-practice framework depicts how the social practice and its supporting institutions mediate between individual motivation and outcome. The framework contains three theoretical conjectures that seek to explain how collectively elaborated standards of excellence prompt developers to produce high-quality software, change institutions, and sustain OSS development. From the framework, we derive six concrete propositions and suggest a new research agenda on motivation in OSS

Improving Software Citation and Credit

The past year has seen movement on several fronts for improving software citation, including the Center for Open Science's Transparency and Openness Promotion (TOP) Guidelines, the Software Publishing Special Interest Group that was started at January's AAS meeting in Seattle at the request of that organization's Working Group on Astronomical Software, a Sloan-sponsored meeting at GitHub in San Francisco to begin work on a cohesive research software citation-enabling platform, the work of Force11 to "transform and improve" research communication, and WSSSPE's ongoing efforts that include software publication, citation, credit, and sustainability. Brief reports on these efforts were shared at the BoF, after which participants discussed ideas for improving software citation, generating a list of recommendations to the community of software authors, journal publishers, ADS, and research authors. The discussion, recommendations, and feedback will help form recommendations for software citation to those publishers represented in the Software Publishing Special Interest Group and the broader community.Comment: Birds of a Feather session organized by the Astrophysics Source Code Library (ASCL, http://ascl.net/ ); to be published in Proceedings of ADASS XXV (Sydney, Australia; October, 2015). 4 page

New methods for clustering district heating users based on consumption patterns

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordUnderstanding energy users’ consumption patterns benefits both utility companies and consumers as it can support improving energy management and usage strategies. The rapid deployment of smart metering facilities has enabled the analysis of consumption patterns based on high-precision real usage data. This paper investigates data-driven unsupervised learning techniques to partition district heating users into separate clusters such that users in the same cluster possess similar consumption pattern. Taking into account the characteristics of heat usage, three new approaches of extracting pattern features from consumption data are proposed. Clustering algorithms with these features are executed on a real-world district heating consumption dataset. The results can reveal typical daily consumption patterns when the consumption linearly related to ambient temperature is removed. Users with heat usages that are highly imbalanced within a certain period of time or are highly consistent with the utility heat production load can also be grouped together. Our methods can facilitate gaining better knowledge regarding the behaviors of district heating users and hence can potentially be used to formulate new pricing and energy reduction solutions.European Commissio

Monte Carlo calculation of the current-voltage characteristics of a two dimensional lattice Coulomb gas

We have studied the nonlinear current-voltage characteristic of a two dimensional lattice Coulomb gas by Monte Carlo simulation. We present three different determinations of the power-law exponent $a(T)$ of the nonlinear current-voltage characteristic, $V \sim I^{a(T)+1}$. The determinations rely on both equilibrium and non-equilibrium simulations. We find good agreement between the different determinations, and our results also agree closely with experimental results for Hg-Xe thin film superconductors and for certain single crystal thin-film high temperature superconductors.Comment: late