A minimum principle for Lagrangian graphs

The classical minimum principle is foundational in convex and complex analysis and plays an important role in the study of the real and complex Monge-Ampere equations. This note establishes a minimum principle in Lagrangian geometry. This principle relates the classical Lagrangian angle of Harvey-Lawson and the space-time Lagrangian angle introduced recently by Rubinstein-Solomon. As an application, this gives a new formula for solutions of the degenerate special Lagrangian equation in space-time in terms of the (time) partial Legendre transform of a family of solutions of obstacle problems for the (space) non-degenerate special Lagrangian equation

Quantization in geometric pluripotential theory

The space of K\"ahler metrics can, on the one hand, be approximated by subspaces of algebraic metrics, while, on the other hand, can be enlarged to finite-energy spaces arising in pluripotential theory. The latter spaces are realized as metric completions of Finsler structures on the space of K\"ahler metrics. The former spaces are the finite-dimensional spaces of Fubini--Study metrics of K\"ahler quantization. The goal of this article is to draw a connection between the two. We show that the Finsler structures on the space of K\"ahler potentials can be quantized. More precisely, given a K\"ahler manifold polarized by an ample line bundle we endow the space of Hermitian metrics on powers of that line bundle with Finsler structures and show that the resulting path length metric spaces recover the corresponding metric completions of the Finsler structures on the space of K\"ahler potentials. This has a number of applications, among them a new approach to the rooftop envelopes and Pythagorean formulas of K\"ahler geometry, a new Lidskii type inequality on the space of K\"ahler metrics, and approximation of finite energy potentials, as well as geodesic segments by the corresponding smooth algebraic objects

Can Europe recover without credit?

Data from 135 countries covering five decades suggests that creditless recoveries, in which the stock of real credit does not return to the pre-crisis level for three years after the GDP trough, are not rare and are characterised by remarkable real GDP growth rates: 4.7 percent per year in middle-income countries and 3.2 percent per year in high-income countries. However, the implications of these historical episodes for the current European situation are limited, for two main reasons. First, creditless recoveries are much less common in highincome countries, than in low-income countries which are financially undeveloped. European economies heavily depend on bank loans and research suggests that loan supply played a major role in the recent weak credit performance of Europe. There are reasons to believe that, despite various efforts, normal lending has not yet been restored. Limited loan supply could be disruptive for the European economic recovery and there has been only a minor substitution of bank loans with debt securities. Second, creditless recoveries were associated with significant real exchange rate depreciation, which has hardly occurred so far in most of Europe. This stylised fact suggests that it might be difficult to re-establish economic growth in the absence of sizeable real exchange rate depreciation, if credit growth does not return

HyPLC: Hybrid Programmable Logic Controller Program Translation for Verification

Programmable Logic Controllers (PLCs) provide a prominent choice of implementation platform for safety-critical industrial control systems. Formal verification provides ways of establishing correctness guarantees, which can be quite important for such safety-critical applications. But since PLC code does not include an analytic model of the system plant, their verification is limited to discrete properties. In this paper, we, thus, start the other way around with hybrid programs that include continuous plant models in addition to discrete control algorithms. Even deep correctness properties of hybrid programs can be formally verified in the theorem prover KeYmaera X that implements differential dynamic logic, dL, for hybrid programs. After verifying the hybrid program, we now present an approach for translating hybrid programs into PLC code. The new tool, HyPLC, implements this translation of discrete control code of verified hybrid program models to PLC controller code and, vice versa, the translation of existing PLC code into the discrete control actions for a hybrid program given an additional input of the continuous dynamics of the system to be verified. This approach allows for the generation of real controller code while preserving, by compilation, the correctness of a valid and verified hybrid program. PLCs are common cyber-physical interfaces for safety-critical industrial control applications, and HyPLC serves as a pragmatic tool for bridging formal verification of complex cyber-physical systems at the algorithmic level of hybrid programs with the execution layer of concrete PLC implementations.Comment: 13 pages, 9 figures. ICCPS 201

Financial Transaction Tax: Small is Beautiful

The case for taxing financial transactions merely to raise more revenues from the financial sector is not particularly strong. Better alternatives to tax the financial sector are likely to be available. However, a tax on financial transactions could be justified in order to limit socially undesirable transactions when more direct means of doing so are unavailable for political or practical reasons. Some financial transactions are indeed likely to do more harm than good, especially when they contribute to the systemic risk of the financial system. However, such a financial transaction tax should be very small, much smaller than the negative externalities in question, because it is a blunt instrument that also drives out socially useful transactions. There is a case for taxing over-the-counter derivative transactions at a somewhat higher rate than exchange-based derivative transactions. More targeted remedies to drive out socially undesirable transactions should be sought in parallel, which would allow, after their implementation, to reduce or even phase out financialtransaction taxes

Ínfű fajok és a lucerna másodlagos kémiai anyagai és hatástani vizsgálatai rovarokon = Allelochemicals from alfalfa and Ajuga plants and those of biological activity on different insect orders

Különböző Ajuga fajok teljes növényi őrleményét (Plodia interpunctella), teljes és frakcionált metanolos kivonatait (Acyrthosiphon pisum, Dysdercus cingulatus, Aedes aegypti, Daphnia magna), valamint tisztított ekdiszteroidok hatékonyságát vizsgáltuk. A Plodia-teszben az A. reptans 8 %-os dózisa azon túl, hogy kétszeresére növelte a posztembrionális kifejlődéshez szükséges időt és csökkentette a bábok súlyát - számottevő mortalitást (77 %) is okozott. Az A. aegypti esetében jelentős hatékonyságot csak az A. reptans 100%-os metanolos frakciója mutatott (0,1 %-os dózisban ~80 %-os mortalitás). A szívó szájszervű rovaroknál (A. pisum, D. cingulatus) A. chamaepitys 100%-os és az A. bracteosa 60%-os frakciói bizonyultak a leghatékonyabbak (0,1 %-os koncentrációban 100 %-os mortalitás). A tisztított ekdiszteroidok közül a 20E és a Polipodin B voltak hatékonyak a levéltetű tesztben (LC50 = 1,07 és 0,21 ppm). Az A. reptans-ból 10 különböző ekdiszteroidot (20-hidroxiekdizon, 20-hidroxiekdizon 3-acetát, ciaszteron, ciaszteron 3-acetát, 29-nor-ciaszteron, ajugaszteron B', ajugalakton, szengoszteron, 23-hidroxi-kapitaszteron, 24-etil-24,26-dihidroxi-taxiszterol 26-metilát) sikerült izolálnunk. Ezek közül két vegyület (23-hidroxi-kapitaszteron, 24-etil-24,26-dihidroxi-taxiszterol 26-metilát) új természetes ekdiszteroidnak bizonyult. Az A. reptans-ból eddig izoláltak közül a 20-hidroxiekdizon 3-acetátot és a ciaszteron 3-acetátot elsőként nyertük ki ebből az Ajuga fajból. | We studied the efficacy of whole plant grist (Plodia interpunctella), crude and fractionated methanolic extracts (Acyrthosiphon pisum, Dysdercus cingulatus, Aedes aegypti, Daphnia magna) as well as pure ecdysteroids from different Ajuga spp. In the Plodia-test the strongest effects were found at 8% concentration of A. reptans grist, which reduced the pupal weight, doubled the postembryonic developmental time, and caused 77% mortality until emergence of adults. In the Aedes-test the crude as well as the 100% methanolic fraction from A. reptans showed high efficacy (80% mortality at 0.1% concentration). In the case of sucking insect species (A. pisum, D. cingulatus) the 100% methanolic fraction of A. chamaepitys and the 60% methanolic fraction of A. bracteosa were highly effective on A. pisum (100% mortality at 0.1% concentration) Polipodine B and 20-hydroxyecdysone were the most effective pure phytoecdysteroids on aphids (LC50 = 0.21 ppm and 1.07 ppm). We have identified 10 different ecdysteroids from the Ajuga reptans var. reptans (20-hydroxyecdysone, 20-hydroxyecdysone acetate, cyasterone, cyasterone 3 acetate, 29-nor-cyasterone, ajugasterone B', ajugalactone, sengosterone, 23-hydroxi-kapitasterone, 24-ethyl-24,26-dihydroxi-taxisterol 26-metilat). Among these 23-hydroxi-capitasterone and 24-ethyl-24,26-dihydroxi-taxisterol 26-metilat are new phytoecdysteroids while, 20-hydroxyecdysone acetate and cyasterone 3 acetate were firstly isolated from A. reptans

Whither growth in central and eastern Europe? Policy lessons for an integrated Europe

In this Blueprint, Bruegel Resident Fellows Zsolt Darvas, Jean Pisani-Ferry, André Sapir and their co-authors Torbjörn Becker, Daniel Daianu, Vladimir Gligorov, Michael A Landesmann, Pavle Petrovic, Dariusz K. Rosati and Beatrice Weder di Mauro argue that in view of the depth of integration in Europe, the development model of the central, eastern and south-eastern Europe (CESEE) region, despite its shortcomings, should be preserved. But it should be reformed, with major implications for policymaking both at national and EU levels. If so, what are the required changes? Bruegel and The Vienna Institute for International Economic Studies (wiiw) cooperated to form this expert group of economists from various European countries to research these issues.