Global existence of a solution to a phase field model for supercooling

In this work, we will derive a macroscopic model of phase field type for supercooling. The phase transition process is described by the evolution of the temperature and the volume fraction of the liquid phase. This phase field model can also be interpreted as the approximation of some generalized Stefan problem. We will prove the existence of solutions to an initial--boundary value problem for the resulting system by using a time discrete scheme

Bodenerosion und Oberflächenabfluss auf einer ökologisch bewirtschafteten Ackerfläche im Sächsischen Lößhügelland

A rainfall simulator was used to describe soil erosion and surface flow on a long-term organically cultivated field. Both parameters did not show differences to conventionally managed and ploughed fields in the same region. These results indicate that soil erosion is fairly independent from the farming system (organic or conventional) but mainly depends on the tillage method

Introduction

This issue contains ten papers presented at the 2008 EAAE/ARCC International Conferenceheld in Denmark. The Royal Danish Academy of Fine Arts, School of Architecture, inCopenhagen graciously and superbly hosted the EAAE/ARCC 2008 conference entitled"Changes of Paradigms in the Basic Understanding of Architectural Research. ArchitecturalResearch and the Digital World.” The papers that follow were selected from over fifty presentedat the conference. The moderators of each paper session and members of the conferenceorganizing committee selected these papers for special recognition. These papers werethen blind peer-reviewed and two papers were selected to receive the designation as ‘BestPaper', one represents the ARCC and one represents the EAAE.Excerpts from the 2008 Conference Introductio

Transcriptional changes in powdery mildew infected wheat and Arabidopsis leaves undergoing syringolin-triggered hypersensitive cell death at infection sites

Blumeria graminis f.sp. tritici, the causal agent of powdery mildew in wheat, is an obligate biotrophic fungus that exclusively invades epidermal cells. As previously shown, spraying of a solution of syringolin A, a circular peptide derivative secreted by the phytopathogenic bacterium Pseudomonas syringae pv. syringae, triggers hypersensitive cell death at infection sites in powdery mildew infected wheat. Thus, the fungus is essentially eradicated. Here we show that syringolin A also triggers hypersensitive cell death in Arabidopsis infected with the powdery mildew fungus Erysiphe cichoracearum. To monitor transcriptional changes associated with this effect, we cloned 307 cDNA clones representing 158 unigenes from powdery mildew infected, syringolin A sprayed wheat leaves by a suppression subtractive hybridization cloning procedure. These cDNAs were microarrayed onto glass slides together with 1088 cDNA-AFLP clones from powdery mildew-infected wheat. Microarray hybridization experiments were performed with probes derived from leaves, epidermal tissue, and mesophyll preparations of mildewed or uninfected wheat plants after syringolin A or control treatment. Similar experiments were performed in Arabidopsis using the Affymetrix ATH1 whole genome GeneChip. The results indicate a conserved mode of action of syringolin A as similar gene groups are induced in both species. Prominent groups include genes associated with the proteasomal degradation pathway, mitochondrial and other heat shock genes, genes involved in mitochondrial alternative electron pathways, and genes encoding glycolytic and fermentative enzymes. Surprisingly, in both species the observed transcriptional response to syringolin A was considerably weaker in infected plants as compared to uninfected plants. The results lead to the working hypothesis that cell death observed at infection sites may result from a parasite-induced suppression of the transcriptional response and thus to insufficient production of protective proteins necessary for the recovery of these cells from whatever insult is imposed by syringolin

Non-Commutative Desingularization of Determinantal Varieties, II

In our paper Non-commutative desingularization of determinantal varieties, I we constructed and studied non-commutative resolutions of determinantal varieties defined by maximal minors. At the end of the introduction we asserted that the results could be generalized to determinantal varieties defined by non-maximal minors, at least in characteristic zero. In this paper we prove the existence of non-commutative resolutions in the general case in a manner which is still characteristic free. The explicit description of the resolution by generators and relations is deferred to a later paper. As an application of our results we prove that there is a fully faithful embedding between the bounded derived categories of the two canonical (commutative) resolutions of a determinantal variety, confirming a well-known conjecture of Bondal and Orlov in this special case

On the derived category of Grassmannians in arbitrary characteristic

In this paper we consider Grassmannians in arbitrary characteristic. Generalizing Kapranov's well-known characteristic-zero results we construct dual exceptional collections on them (which are however not strong) as well as a tilting bundle. We show that this tilting bundle has a quasi-hereditary endomorphism ring and we identify the standard, costandard, projective and simple modules of the latter

On the derived category of Grassmannians in arbitrary characteristic

In this paper we consider Grassmannians in arbitrary characteristic. Generalizing Kapranov's well-known characteristic-zero results we construct dual exceptional collections on them (which are however not strong) as well as a tilting bundle. We show that this tilting bundle has a quasi-hereditary endomorphism ring and we identify the standard, costandard, projective and simple modules of the latter.Comment: 22 pages, revisions as suggested by the referee

A Characteristic Free Tilting Bundle for Grassmannians

We construct a characteristic free tilting bundle on Grassmannians