Nonfree datatypes in Isabelle/HOL: animating a many-sorted metatheory

Datatypes freely generated by their constructors are well supported in mainstream proof assistants. Algebraic specification languages offer more expressive datatypes on axiomatic means: nonfree datatypes generated from constructors modulo equations. We have implemented an Isabelle/HOL package for nonfree datatypes, without compromising foundations. The use of the package, and its nonfree iterator in particular, is illustrated with examples: bags, polynomials and λ-terms modulo α-equivalence. The many-sorted metatheory of nonfree datatypes is formalized as an ordinary Isabelle theory and is animated by the package into user-specified instances. HOL lacks a type of types, so we employ an ad hoc construction of a universe embedding the relevant parameter types

Rice Age: Comments on the Panel Report in Turkey - Measures Affecting the Importation of Rice

At face value, Turkey-Rice is not the most complex or important WTO dispute ever litigated. The facts of the case give strong reason to believe that Turkey's restrictions on rice imports from the United States were not GATT-consistent. Turkey's steadfast refusal to provide exonerating evidence in its defence and the Panel's drawing of appropriate inference were probably the most remarkable issues of the case. Nevertheless, Turkey-Rice raises at least one interesting legal and economic question: How ‘activist' are dispute panels today, and how interventionist should they be during the litigation process? We discuss the justification and role of activist panels and assess the consequences for parties' strategic behavior and incentive to provide accurate informatio

Relations between replant disease, growth parameters and mineral nutrition status of grapevines (Vitis sp.)

Grapevine cultivars Riesling (Vitis vinifera L.), 5 C (V. berlandieri PLANCH. x V. riparia MICHX.), Riesling grafted on rootstock cultivar 5 C (Riesling/5 C) and maize (Zea may L.) were grown in pots on a soil from a grapevine nursery affected with replant disease and on a soil that had not been planted with grapevines before. On replant soil the grapevines, in particular 5 C and Riesling/5 C, were severely inhibited in shoot and root growth, while ungrafted Riesling was less affected. In contrast, maize produced similar dry weights on both soils. There was no causal relationship between the incidence of replant disease in grapevines and their nutritional status, regarding macro- and micronutrients. However, compared to non-replant soil, on replant soil the manganese concentrations in shoots of all grapevine types were significantly lower, indicating an alteration of microbial activity and/or microbial composition in the rhizosphere of grapevines. Grapevine replant disease could not be induced in a soil by incubating the tenfold amount of grapevine roots, that seasonally remain in the nursery soil. Thus, the growth inhibition of grapevines cannot be attributed to substances released from dead grapevine roots of the degradation products. Obviously, factors associated with living roots (rhizosphere) are an essential prerequisite for the development of replant disease. The elimination of replant disease by steam sterilization of replant soil supports the assumption, that rhizosphere microorganisms are involved with grapevine replant disease

Improved red-response in thin film a-Si:H solar cells with soft-imprinted plasmonic back reflectors

The impact of controlled nanopatterning on the Ag back contact of an n-i-p a-Si:H solar cell was investigated experimentally and through electromagnetic simulation. Compared to a similar reference cell with a flat back contact, we demonstrate an efficiency increase from 4.5% to 6.2%, with a 26% increase in short circuit current density. Spectral response measurements show the majority of the improvement between 600 and 800 nm, with no reduction in photocurrent at wavelengths shorter than 600 nm. Optimization of the pattern aspect ratio using electromagnetic simulation predicts absorption enhancements over 50% at 660 nm

Light trapping in ultrathin plasmonic solar cells

We report on the design, fabrication, and measurement of ultrathin film a-Si:H solar cells with nanostructured plasmonic back contacts, which demonstrate enhanced short circuit current densities compared to cells having flat or randomly textured back contacts. The primary photocurrent enhancement occurs in the spectral range from 550 nm to 800 nm. We use angle-resolved photocurrent spectroscopy to confirm that the enhanced absorption is due to coupling to guided modes supported by the cell. Full-field electromagnetic simulation of the absorption in the active a-Si:H layer agrees well with the experimental results. Furthermore, the nanopatterns were fabricated via an inexpensive, scalable, and precise nanopatterning method. These results should guide design of optimized, non-random nanostructured back reflectors for thin film solar cells

Vergleichende Untersuchungen über die Empfindlichkeit von 6 Unterlagensorten der Weinrebe gegenüber Phosphat-induziertem Zink-Mangel

In Gefäßversuchen mit den Unterlagensorten 143 A M.G., 125 AA, 26 G., 5 C, 5 BB und 8 B führte steigende Phosphat-Düngung eines Zn-armen Bodens zum Absinken der Zn-Gehalte in den jüngeren Blättern bei allen 6 Sorten. Starke Wachstumsdepressionen des Sprosses und Zn-Mangelsymptome an den jungen Blättern traten aber nur bei den Sorten 5 BB und 8 B auf.In Wasserkulturversuchen kam es dagegen bei steigenden Phosphat-Konzentrationen zu keiner oder nur geringfügiger Absenkung der Zn-Gehalte in den jüngeren Blättern, und bei keiner der 6 Sorten traten Wachstumsdepressionen oder deutliche Zn-Mangelsymptome auf, obwohl die P-Gehalte in den jungen Blättern wesentlich stärker anstiegen als beim Versuch im Boden. Dadurch stieg das P/Zn-Verhältnis in diesen Blättern ohne Auftreten von Zn-Mangelsymptomen auf über 1000 an.Bei gleichbleibender Rate der Zn-Aufnahme durch die Wurzeln und Einlagerung in die jungen, wachsenden Blätter kann der Zn-Grenzwert in diesen Blättern auch bei sehr hohen P-Gehalten offenbar bei allen 6 Sorten sehr niedrig liegen (unter 14 μg Zn/g T.S.). Im Boden, insbesondere unter Freilandbedingungen, dürfte die Aufnahmerate von Zn aber größeren Schwankungen unterliegen (z. B. bei Bodenaustrocknung), wodurch erst höhere Zn-Gehalte der Blätter eine im Mittel ausreichende Einlagerungsrate von Zn widerspiegeln.Das Auftreten von Phosphat-induziertem Zn-Mangel bei den Sorten 5 BB und 8 B im Boden, nicht aber in Nährlösung, ist vermutlich auf die schwächere Wurzelausbildung gegenüber den anderen Sorten zurückzuführen. Unter ungünstigen Umweltbedingungen, vor allem, wenn durch niedrige Lichtintensitäten das Wurzelwachstum vermindert ist, wird bei diesen beiden Sorten die Gefahr des Auftretens von Zn-Mangel besonders groß sein.Comparative studies on the sensitivity of six rootstock varieties of grapevine to phosphate-induced Zn deficiencyIn pot experiments with the rootstock varieties 143 A M.G., 125 AA, 26 G., 5 C, 5 BB and 8 B, increasing phosphate fertilization of a soil deficient in zinc led to a decrease in the zinc content of the younger Ieaves in all six varieties. Extreme growth depressions of the shoots and symptoms of zinc deficiency in the young leaves, however, appeared only in the varieties 5 BB and 8 B. In water culture experiments, by contrast, increasing phosphate concentrations led to no decrease at all or only to a slight one of the zinc content in the younger leaves, and growth depressions or distinct symptoms of zinc deficiency appeared in none of the six varieties, although the phosphorus content in the young leaves increased to a considerably greater degree than in the soil experiment. The P/Zn ratio rose thereby in these leaves to over 1000 without the occurrence of zinc deficiency symptoms.With a constant rate of zinc uptake through the roots and translocation into the young, growing leaves, the "critical" zinc concentrations in these leaves can apparently be very low (below 14 ftg Zn/g dry matter), even with very high phosphorus contents. In the soil, particularly under outdoor conditions, however, the uptake rate of zinc may vary considerably (e.g. in the case of high fluctuations of the soil water content), so that only higher zinc contents of the leaves reflect that on the average the translocation rate of Zn into the leaves during leaf development was sufficient.The occurence of zinc deficiency induced by phosphate in the varieties 5 BB and 8 B in the soil, but not in the nutrient solution, can probably be attributed to the smaller root system in comparison with the other varieties. Under unfavourable environmental conditions, especially when root growth is restricted by low light intensities, both these varieties should be particularly susceptible to Zn deficiency

Optical response of silver nanoneedles on a mirror

Plasmonic properties of metal nanostructures are appealing due to their potential to enhance photovoltaics or sensing performance. Our aim was to identify the plasmonic characteristics of silver nanoneedles on a reflective layer in the polarized optical response. Experimental ellipsometry results are complemented by finite-difference time-domain (FDTD) calculations. Plasmon resonances on the nanoneedles can indeed be observed in the polarized optical response. This study reveals the details of the complex antenna-like behaviour of the nanoneedles which gives an agreement between experiment and FDTD simulation. The simulations show that the plasmon resonances lead to an effective negative refractive index, originating from the negative refractive index of the nanoneedles in combination with its supporting substrate, i.e. a mirror. This original study of a complex plasmonic system by ellipsometry and FDTD has great relevance for applications, making use of intricate light matter interaction

Einfluss unterschiedlicher Inokulationstiefen mit dem arbuskulären Mykorrhizapilz Glomus mosseae auf die Mykorrhizierung bei Reben (Vitis sp.) in Wurzelbeobachtungskästen

In einem Gefäßversuch mit Grünstecklingen der Unterlagssorte SO 4 (Vitis berlandieri x Vitis riparia) wurde der Einfluss einer unterschiedlichen Bandinokulation mit dem AM-Pilz Glomus mosseae (Nicol. et Gerd.) Gerdemann et Trappe auf die Entwicklung des Pilzes innerhalb des Wurzelsystems untersucht. Hierbei wurde in 70 cm tiefe Wurzelbeobachtungskästen mit einem P-armen, sterilisierten Rebschulboden in eine Tiefe von 9-18 cm bzw. 36-45 cm eine 9 cm dicke Inokulationsschicht eingebracht. Im unmittelbaren Inokulationsbereich war bei beiden Inokulationsvarianten mit 45 bzw. 35% der AM-Infektionsgrad am höchsten. Mit zunehmendem Abstand vom Inokulationsband waren die Rebwurzeln geringer mykorrhiziert bzw. es konnte keine AM-Infektion festgestellt werden. Durch die Inokulation im oberen Bodenbereich wurden Trockengewicht und P-Gehalt der SO 4-Stecklinge erhöht. Die Zn-Gehalte in den Blattspreiten waren bei beiden Inokulationsmethoden erhöht, der Cu-Gehalt bei Inokulation des unteren Bodenbereichs. Bereits eine Teilbesiedlung des Wurzelsystems mit AM führte zu ausreichenden Inokulationserfolgen in Form von erhöhten Nährstoffgehalten in den Blättern und erhöhter Trockensubstanzbildung. Die Inokulation in der größeren Bodentiefe (36-45 cm) führte zu einer verzögerten Mykorrhizierung der Wurzeln, so dass möglicherweise die positiven Effekte des AM-Pilzes bei dieser Inokulationsmethode nicht zum Tragen kamen.Influence of different inoculum places of the mycorrhizal fungus Glomus mosseae on mycorrhizal colonization in grapevine rootstocks (Vitis sp.)Grapevine rootstocks (Vitis berlandieri x Vitis riparia, cv. SO 4) were grown in pots with sterilised soil with low P level from a nursery to test the effect of a local supply of inoculum of an arbuscular mycorrhizal fungus (Glomus mosseae [Nicol. et Gerd.] Gerdemann et Trappe) on mycorrhizal colonization of the root system. The inoculum was placed in a 9-cm deep band either in 9-18 cm or in 36-45 cm soil depths. After 6 weeks of growth, mycorrhizal colonisation of roots was highest in the inoculated soil zone. With increasing distance from the inoculum band, mycorrhizal colonization decreased or was absent. When the inoculum was placed in the top soil, the shoot dry weight and the leaf blade Zn and P concentrations significantly increased in mycorrhizal as compared to nonmycorrhizal plants. When the inoculum was placed in 36-45 cm soil depth, leaf blade Zn and Cu concentrations increased in mycorrhizal plants, but shoot dry weight was not affected. In conclusion, a locally restricted mycorrhizal colonization of the root system was sufficient to increase growth and nutrient uptake of grape rootstocks