New Superconducting and Semiconducting Fe-B Compounds Predicted with an Ab Initio Evolutionary Search

New candidate ground states at 1:4, 1:2, and 1:1 compositions are identified in the well-known Fe-B system via a combination of ab initio high-throughput and evolutionary searches. We show that the proposed oP12-FeB2 stabilizes by a break up of 2D boron layers into 1D chains while oP10-FeB4 stabilizes by a distortion of a 3D boron network. The uniqueness of these configurations gives rise to a set of remarkable properties: oP12-FeB2 is expected to be the first semiconducting metal diboride and oP10-FeB4 is shown to have the potential for phonon-mediated superconductivity with a Tc of 15-20 K.Comment: 7 pages, 6 figure

Inducing resistance: a summary of papers presented at the First International Symposium on Induced Resistance to Plant Diseases, Corfu, May 2000

The First International Symposium on Induced Resistance to Plant Diseases, organized by Eris Tjamos, brought together over 150 participants to discuss the complexities, questions and future direction of research on the mechanisms by which plants can become better able to defend themselves against pathogen attack. Although the term immunization has been used to denote treatments that enhance the defensive capacity of plants, the correspondence to vaccination in vertebrates is far-fetched: the induced state is by no means specific, but rather constitutes a more general increase in plant resistance to various types of pathogens. Moreover, it seldom prevents disease from occurring but generally reduces its extent or severity. These characteristics make induced resistance a powerful mechanism to exploit for enhancing the overall resistance in crop plants. Indeed, the first commercial chemical triggering induced resistance in plants, acibenzolar-Smethyl (BTH) was recently introduced on the market by Novartis under the tradenames Actigard (USA) and BION (Europe)

An intercomparison of procedures for the determination of total mercury in seawater and recommendations regarding mercury speciation during GEOTRACES cruises

Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 10 (2012): 90-100, doi:10.4319/lom.2012.10.90.We conducted a laboratory intercomparison of total mercury (Hg) determination in seawater collected during U.S. GEOTRACES Intercalibration cruises in 2008 and 2009 to the NW Atlantic and NE Pacific Oceans. Results indicated substantial disagreement between the participating laboratories, which appeared to be affected most strongly by bottle cleanliness and preservation procedures. In addition, we examined the effectiveness of various collection and sample preparation procedures that may be used on future GEOTRACES cruises. The type of sampling system and filtration medium appeared to make little difference to results. Finally, and in light of results from experiments that considered sample bottle material effect and the development of new methods for CH3Hg+ extraction from seawater, we propose a recommended procedure for determining all four of the major Hg species in seawater (elemental, dimethyl-, monomethyl-, and total Hg).This work was supported by the National Science Foundation program in Chemical Oceanography under grants OCE–0825157, –0825108, –0825583 and –0825068

Control of fine-structure splitting and excitonic binding energies in selected individual InAs/GaAs quantum dots

A systematic study of the impact of annealing on the electronic properties of single InAs/GaAs quantum dots (QDs) is presented. Single QD cathodoluminescence spectra are recorded to trace the evolution of one and the same QD over several steps of annealing. A substantial reduction of the excitonic fine-structure splitting upon annealing is observed. In addition, the binding energies of different excitonic complexes change dramatically. The results are compared to model calculations within eight-band k.p theory and the configuration interaction method, suggesting a change of electron and hole wave function shape and relative position.Comment: 4 pages, 4 figure

Major host transitions are modulated through transcriptome-wide reprogramming events inSchistocephalus solidus, a threespine stickleback parasite

Parasites with complex life cycles have developed numerous phenotypic strategies, closely associated with developmental events, to enable the exploitation of different ecological niches and facilitate transmission between hosts. How these environmental shifts are regulated from a metabolic and physiological standpoint, however, still remain to be fully elucidated. We examined the transcriptomic response of Schistocephalus solidus, a trophically-transmitted parasite with a complex life cycle, over the course of its development in an intermediate host, the threespine stickleback, and the final avian host. Results from our differential gene expression analysis show major reprogramming events among deve lopmental stages. The final host stage is characterized by a strong activation of reproductive pathways and redox homeostasis. The attainment of infectivity in the fish intermediate host – which precedes sexual maturation in the final host and is associated with host behaviour changes – is marked by transcription of genes involved in neural pathways and sensory perception. Our results suggest that un(annotated and S. solidus (specific genes could play a determinant role in host-parasite molecular interactions required to complete the parasite's life cycle. Our results permit future comparative analyses to help disentangle species-specific patterns of infection from conserved mechanisms, ultimately leading to a better understanding of the molecular control and evolution of complex life cycles

Jung und Alt im Hörsaal:Erfahrungen jüngerer Studierender mit dem „Studium im Alter“ an der Universität Münster

Das „Studium im Alter“ ist ein Weiterbildungsangebot der Universität Münster für Personen im mittleren und höheren Lebensalter, die als Gasthörer gemeinsam mit jüngeren, regulären Studierenden Vorlesungen und Seminare an der Hochschule besuchen. In der Presse erschienen von Zeit zu Zeit Berichte über Konflikte, die das Gaststudium der Älteren in den Hörsälen verursacht. Das nahm eine Gruppe von Teilnehmern am „Studium im Alter“ zum Anlass, in einem zweisemestrigen Forschungsprojekt zu untersuchen, inwiefern solche Berichte die Regel oder Einzelfälle beschreiben. Das Ergebnis der schriftlichen Befragung regulärer Studierender zu Ihren Erfahrungen mit Studierenden im Alter liegt mit dieser Studie vor. Abgesehen von wenigen Ausnahmen belegt sie ein grundsätzlich harmonisches Miteinander von jüngeren und älteren Studierenden in den Hörsälen der Universität Münster

Toxicity of dietary methylmercury to fish: Derivation of ecologically meaningful threshold concentrations

Threshold concentrations associated with adverse effects of dietary exposure to methylmercury (MeHg) were derived from published results of laboratory studies on a variety of fish species. Adverse effects related to mortality were uncommon, whereas adverse effects related to growth occurred only at dietary MeHg concentrations exceeding 2.5 µg g −1 wet weight. Adverse effects on behavior of fish had a wide range of effective dietary concentrations, but generally occurred above 0.5 µg g −1 wet weight. In contrast, effects on reproduction and other subclinical endpoints occurred at dietary concentrations that were much lower (<0.2 µg g −1 wet wt). Field studies generally lack information on dietary MeHg exposure, yet available data indicate that comparable adverse effects have been observed in wild fish in environments corresponding to high and low MeHg contamination of food webs and are in agreement with the threshold concentrations derived here from laboratory studies. These thresholds indicate that while differences in species sensitivity to MeHg exposure appear considerable, chronic dietary exposure to low concentrations of MeHg may have significant adverse effects on wild fish populations but remain little studied compared to concentrations in mammals or birds. Environ. Toxicol. Chem. 2012; 31: 1536–1547. © 2012 SETACPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92130/1/etc_1859_sm_SupplReferences.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/92130/2/1859_ftp.pd

Ab initio study of the modification of elastic properties of alpha-iron by hydrostatic strain and by hydrogen interstitials

The effect of hydrostatic strain and of interstitial hydrogen on the elastic properties of $\alpha$-iron is investigated using \textit{ab initio} density-functional theory calculations. We find that the cubic elastic constants and the polycrystalline elastic moduli to a good approximation decrease linearly with increasing hydrogen concentration. This net strength reduction can be partitioned into a strengthening electronic effect which is overcome by a softening volumetric effect. The calculated hydrogen-dependent elastic constants are used to determine the polycrystalline elastic moduli and anisotropic elastic shear moduli. For the key slip planes in $\alpha$-iron, $[1\bar{1}0]$ and $[11\bar{2}]$, we find a shear modulus reduction of approximately 1.6% per at.% H.Comment: Updated first part of 1009.378