Evolution of a fluorinated green fluorescent protein

The fluorescence of bacterial cells expressing a variant (GFPm) of the green fluorescent protein (GFP) was reduced to background levels by global replacement of the leucine residues of GFPm by 5,5,5-trifluoroleucine. Eleven rounds of random mutagenesis and screening via fluorescence-activated cell sorting yielded a GFP mutant containing 20 amino acid substitutions. The mutant protein in fluorinated form showed improved folding efficiency both in vivo and in vitro, and the median fluorescence of cells expressing the fluorinated protein was improved {approx}650-fold in comparison to that of cells expressing fluorinated GFPm. The success of this approach demonstrates the feasibility of engineering functional proteins containing many copies of abiological amino acid constituents

Taxation of Distributions from Accumulation Trusts: The Impact of the Tax Reform Act of 1976

The complex rules governing the taxation of income from trusts and estates have at times been described as incomprehensible. Perhaps the most confusing of these are the accumulation distribution throwback rules. In an effort to alleviate some of this confusion, Congress included accumulation trusts within the purview of the Tax Reform Act of 1976. Though Congress claimed that the rules are now considerably simplified, it is not without some effort that one is able to translate the statutory language into a form useful to the practitioner. Given the complexity of the rules, it is necessary to begin with a caveat. This article is prepared with the assumption that the reader knows something of accumulation trusts and their income taxation. Only so much of the general theory and operation of the throwback rules will be explained as is necessary to introduce the changes made by the 1976 Act and to illustrate their effect. It is hoped that in this way the new rules may be succinctly presented without unnecessary forays into areas essentially unaffected by them

Conflict and cooperation in the water-security nexus: A global comparative analysis of river basins under climate change

Adequate fresh water availability is an important factor for human security in many parts of the world. In transboundary river basins, decreased water supply due to local environmental change and global climate change and increased water demand due to growing populations and continued economic development can aggravate water scarcity. Contrary to the claim that water scarcity may result in an increased risk of armed conflict, there is no simple relationship between freshwater availability and violent conflict. Other crucial factors need to be taken into consideration that also directly influence resource availability and personal human well‐being. In this review, we assess the scientific literature on conflict and cooperation in transboundary river systems. Most international river basins are already jointly managed by the riparians, but successful management in times of climate change necessitates the inclusion of more factors besides mere allocation schemes. On the basis of a substantial body of literature on the management of transboundary watersheds, an analytical framework of the water‐security nexus is developed that integrates the physical and socioeconomic pathways connecting water availability with conflict or cooperation. This framework is subsequently applied to two transboundary river basins—the Nile River and the Syr Darya/Amu Darya—as they represent two world regions that could become future water hot spots. An improved understanding of the developments leading to water conflicts and their interaction can help to successfully reduce the risk of water conflicts in these regions and to move toward increased cooperation among the riparians of transboundary river systems

Measurements of thermodynamic and transport properties of EuC2_2: a low-temperature analogue of EuO

EuC$_2$ is a ferromagnet with a Curie-temperature of $T_C \simeq 15\,$K. It is semiconducting with the particularity that the resistivity drops by about 5 orders of magnitude on cooling through $T_C$, which is therefore called a metal-insulator transition. In this paper we study the magnetization, specific heat, thermal expansion, and the resistivity around this ferromagnetic transition on high-quality EuC$_2$ samples. At $T_C$ we observe well defined anomalies in the specific heat $c_p(T)$ and thermal expansion $\alpha(T)$ data. The magnetic contributions of $c_p(T)$ and $\alpha(T)$ can satisfactorily be described within a mean-field theory, taking into account the magnetization data. In zero magnetic field the magnetic contributions of the specific heat and thermal expansion fulfill a Gr\"uneisen-scaling, which is not preserved in finite fields. From an estimation of the pressure dependence of $T_C$ via Ehrenfest's relation, we expect a considerable increase of $T_C$ under applied pressure due to a strong spin-lattice coupling. Furthermore the influence of weak off stoichiometries $\delta$ in EuC$_{2 \pm \delta}$ was studied. It is found that $\delta$ strongly affects the resistivity, but hardly changes the transition temperature. In all these aspects, the behavior of EuC$_2$ strongly resembles that of EuO.Comment: 7 pages, 6 figure

Antiferroquadrupolar Order in the Magnetic Semiconductor TmTe

The physical properties of the antiferroquadrupolar state occurring in TmTe below TQ=1.8 K have been studied using neutron diffraction in applied magnetic fields. A field-induced antiferromagnetic component k = (1/2,1/2,1/2) is observed and, from its magnitude and direction for different orientations of H, an O(2,2) quadrupole order parameter is inferred. Measurements below TN ~= 0.5 K reveal that the magnetic structure is canted, in agreement with theoretical predictions for in-plane antiferromagnetism. Complex domain repopulation effects occur when the field is increased in the ordered phases, with discontinuities in the superstructure peak intensities above 4 T.Comment: 6 pages, 6 figures, Presented at the International Conference on Strongly Correlated Electrons with Orbital Degrees of Freedom (ORBITAL 2001), September 11-14, 2001 (Sendai, JAPAN). To appear in: Journal of the Physical Society of Japan (2002

On exposure, vulnerability and violence: Spatial distribution of risk factors for climate change and violent conflict across Kenya and Uganda

Recent studies discuss the link between climate change and violent conflict, especially for East Africa. While there is extensive literature on the question whether climate change increases the risk of violent conflict onset, not much is known about where a climate-conflict link is most likely to be found. We address this question by analyzing the spatial distribution of the factors commonly associated with a high exposure and vulnerability to climate change, and a high risk of violent conflict onset in Kenya and Uganda. Drawing on recent literature and quantitative data for the period 1998–2008, we develop various specifications of a composite risk index (CRI) with a spatial resolution of half a degree for Kenya and Uganda in the year 2008. A quantitative comparison with conflict data for the year 2008 provides support for the composite risk index. Finally, the composite risk index is contrasted with the findings of three qualitative case studies, which provide mixed support for the index and help to identify its strengths and weaknesses as well as conceptual needs for further quantitative studies on climate change and violent conflict