Managing the business: potential and pitfalls of water rights and water tariffs in allocating and managing water in water stressed basins: the case of Rufiji Basin in Tanzania

River basinsWater stressWater resource managementWater rightsWater ratesWater allocation

On the Ehrenfest theorem of quantum mechanics

We give a mathematically rigorous derivation of Ehrenfest's equations for the evolution of position and momentum expectation values, under general and natural assumptions which include atomic and molecular Hamiltonians with Coulomb interactions.Comment: To appear in J. Math. Phy

Formal water rights in rural Tanzania: Deepening the dichotomy?

Water rights / Water law / Water scarcity / Water use / Water users’ associations / Irrigation water / Cost recovery

Fraglight:shedding light on broken pointcuts in evolving aspect-oriented software

Pointcut fragility is a well-documented problem in Aspect-Oriented Programming; changes to the base-code can lead to join points incorrectly falling in or out of the scope of pointcuts. Deciding which pointcuts have broken due to base-code changes is a daunting venture, especially in large and complex systems. We demonstrate an automated tool called FRAGLIGHT that recommends a set of pointcuts that are likely to require modification due to a particular base-code change. The underlying approach is rooted in harnessing unique and arbitrarily deep structural commonality between program elements corresponding to join points selected by a pointcut in a particular software version. Patterns describing such commonality are used to recommend pointcuts that have potentially broken with a degree of confidence as the developer is typing. Our tool is implemented as an extension to the Mylyn Eclipse IDE plug-in, which maintains focused contexts of entities relevant to a task

Initial Ionization of Compressible Turbulence

We study the effects of the initial conditions of turbulent molecular clouds on the ionization structure in newly formed H_{ii} regions, using three-dimensional, photon-conserving radiative transfer in a pre-computed density field from three-dimensional compressible turbulence. Our results show that the initial density structure of the gas cloud can play an important role in the resulting structure of the H_{ii} region. The propagation of the ionization fronts, the shape of the resulting H_{ii} region, and the total mass ionized depend on the properties of the turbulent density field. Cuts through the ionized regions generally show ``butterfly'' shapes rather than spherical ones, while emission measure maps are more spherical if the turbulence is driven on scales small compared to the size of the H_{ii} region. The ionization structure can be described by an effective clumping factor $\zeta=< n > \cdot /^2$, where $n$ is number density of the gas. The larger the value of $\zeta$, the less mass is ionized, and the more irregular the H_{ii} region shapes. Because we do not follow dynamics, our results apply only to the early stage of ionization when the speed of the ionization fronts remains much larger than the sound speed of the ionized gas, or Alfv\'en speed in magnetized clouds if it is larger, so that the dynamical effects can be negligible.Comment: 9 pages, 10 figures, version with high quality color images can be found in http://research.amnh.org/~yuexing/astro-ph/0407249.pd

Migraine and vascular disease biomarkers: A population-based case-control study.

Background The underpinnings of the migraine-stroke association remain uncertain, but endothelial activation is a potential mechanism. We evaluated the association of migraine and vascular disease biomarkers in a community-based population. Methods Participants (300 women, 117 men) were recruited as a part of the Dutch CAMERA 1 (Cerebral Abnormalities in Migraine, an Epidemiologic Risk Analysis) study. Participants were aged 30-60 (mean 48) years, 155 migraine had with aura (MA), 128 migraine without aura (MO), and 134 were controls with no severe headaches. Plasma concentrations of fibrinogen, Factor II, D-dimer, high sensitivity C-reactive protein (hs-CRP), and von Willebrand factor antigen were compared between groups, also stratifying by sex. Results Fibrinogen and hs-CRP were elevated in migraineurs compared to controls. In logistic regression analyses, MO and MA had increased likelihood of elevated fibrinogen, and MA had increased likelihood of elevated Factor II and hs-CRP. Fibrinogen and Factor II were associated with MA in women but not men. In the migraine subgroup, the total number of years of aura, but not headache, predicted elevated hs-CRP, and the average number of aura, but not headache, attacks predicted all biomarkers but Factor II. Conclusions Elevated vascular biomarkers were associated with migraine, particularly MA, as well as with years of aura and number of aura attacks

Cross-disciplinary approaches to linguistic variation in Early Modern West Germanic

This thematic issue on Early Modern West Germanic homes in on the processes underlying the extensive amount of morphosyntactic variation and change within and between language users in this era. It demonstrates that language structure and language use often interacted with each other, and illustrates that, to fully understand the triggers and extent of this variation and change, we need to combine perspectives and methodological tools from different (sub)disciplines. That is why this issue brings together scholars working on Early Modern West Germanic in different fields and disciplines – in particular scholars from early modern literary studies, formal (historical) linguistics, computational linguistics and historical sociolinguistics – to present a wide array of possible methodologies to investigate historical language variation, and to explore how the different approaches can complement each other to help further our understanding of the complex setting of variation

Chemical Abundance Gradients in the Star-Forming Ring Galaxies

Ring waves of star formation, propagating outwardly in the galactic disks, leave chemical abundance gradients in their wakes. We show that the relative [Fe/O] abundance gradients in ring galaxies can be used as a tool for determining the role of the SNIa explosions in their chemical enrichment. We consider two mechanisms which can create outwardly propagating star forming rings in a purely gaseous disk -- a self-induced wave and a density wave, and demonstrate that the radial distribution of the relative [Fe/O] abundance gradients does not depend on the particular mechanism of the wave formation or on the parameters of the star-forming process. We show that the [Fe/O] profile is determined by the velocity of the wave, initial mass function, and the initial chemical composition of the star-forming gas. If the role of SNIa explosions is negligible in the chemical enrichment, the ratio [Fe/O] remains constant throughout the galactic disk with a steep gradient at the wave front. If SNIa stars are important in the production of cosmic iron, the [Fe/O] ratio has gradient in the wake of the star-forming wave with the value depending on the frequency of SNIa explosions.Comment: Uses aas2pp4.sty and epsfig.sty, 7 pages including one figure To appear in Astrophysical Journa