Geometric Invariant Theory based on Weil Divisors

Given an action of a reductive group on a normal variety, we construct all invariant open subsets admitting a good quotient with a quasiprojective or a divisorial quotient space. Our approach extends known constructions like Mumford's Geometric Invariant Theory. We obtain several new Hilbert-Mumford type theorems, and we extend a projectivity criterion of Bialynicki-Birula and Swiecicka for varieties with semisimple group action from the smooth to the singular case.Comment: Final version, to appear in Compositio Mat

Effiziente Viterbi Decodierung und Anwendung auf die Bildübertragung in gestörten Kanälen

Faltungscodes ist der Viterbi Algorithmus, der aus einem empfangenen, codierten Datenblock die Daten ermittelt, die der Sender mit höchster Wahrscheinlichkeit gesendet hat. Auf dem Viterbi Algorithmus basieren die List Viterbi Algorithmen, die nicht nur die wahrscheinlichste Lösung, sondern eine Liste der n wahrscheinlichsten Lösungen (Pfade) finden. Im ersten Teil der Arbeit werden die aus der Literatur bekannten List Viterbi Algorithmen beschrieben, analysiert und hinsichtlich ihrer Komplexität verglichen. Es wird außerdem eine spezielle Implementation des Tree Trellis Algorithmusvorgeschlagen, durch die eine Komplexitätsreduzierung von quadratischer auf lineare Zeitkomplexität möglich ist. Der zweite Teil der Arbeit betrachtet die Anwendung von Faltungscodes auf die Bildübertragung. Es wird gezeigt, daß die durch die Reduzierung der Zeitkomplexität mögliche Erhöhung der Anzahl der bei der Decodierung betrachteten Pfade die Ergebnisse eines bestehenden Verfahrens zur Bildübertragung signifikant verbessert

Impact of the introduction of decoupled payments on functioning of the German land market: Country report of the EU tender Study on the functioning of land markets in those EU member states influenced by measures applied under the Common Agricultura

Against the background of the reform of the Common Agricultural Policy (CAP) in 2003 the following analysis, brings into focus the responses of the agricultural sector to decoupled subsidies. In particular it addresses the impact of the Single Payment Scheme (SPS) on land sales and rent prices and therefore on farm structure. It also aims to assess the extent to which the reform advances sound and sustainable agriculture and provides incentives for marketorientated farming practices. The study is based on the analysis of statistical data and expert surveys conducted in three selected regions. -- G E R M A N V E R S I O N: Die vorliegende Studie untersucht den Einfluss der 2003 im Zuge der Reform der Gemeinsamen Agrarpolitik (GAP) durchgeführten Entkopplung der Direktzahlungen auf den Agrarsektor in Deutschland. Besonderer Fokus der Analyse liegt auf der Auswirkung der einmaligen Zahlungen auf die Kauf- und Pachtpreise für das landwirtschaftlich genutzte Land. Des Weiteren wird die Förderung einer nachhaltigen und marktorientierten Landwirtschaft durch die GAP-Reform bewertet. Die Untersuchung basiert auf Auswertung statistischer Daten und auf Expertenbefragungen, welche in drei ausgewählten Bundesländern durchgeführt wurden.Land markets,midterm review,CAP,structural change,Bodenmärkte,Halbzeitbewertung,GAP,Strukturwandel

Predictive value of the Acute Low Back Pain Screening Questionnaire and the Örebro Musculoskeletal Pain Screening Questionnaire for persisting problems

Introduction: A small proportion of individuals with non-specific low back pain (NSLBP) develop persistent problems. Up to 80% of the total costs for NSLBP are owing to chronic NSLBP. Psychosocial factors have been described to be important in the transition from acute to chronic NSLBP. Guidelines recommend the use of the Acute Low Back Pain Screening Questionnaire (ALBPSQ) and the Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) to identify individuals at risk of developing persistent problems, such as long-term absence of work, persistent restriction in function or persistent pain. These instruments can be used with a cutoff value, where patients with values above the threshold are further assessed with a more comprehensive examination. Methods: We systematically reviewed studies evaluating the accuracy of the ALBPSQ and ÖMPSQ to predict persistent problems. Results: The 13 included studies used different cutoff values for the screening questionnaires ranging from 68 to 147. The pooled sensitivity was 0.59 (0.43-0.74), while the pooled specificity was 0.77 (0.66-0.86). Heterogeneity (I 2) was 90.02% for sensitivity and 95.41% for specificity. Conclusion: Thus, we do not recommend the use of one cutoff value, but the use of a prediction model with all the individual item

Shifts of attention in the early blind: an ERP study of attentional control processes in the absence of visual spatial information

To investigate the role of visual spatial information in the control of spatial attention, event-related brain potentials (ERPs) were recorded during a tactile attention task for a group of totally blind participants who were either congenitally blind or had lost vision during infancy, and for an age-matched, sighted control group who performed the task in the dark. Participants had to shift attention to the left or right hand (as indicated by an auditory cue presented at the start of each trial) in order to detect infrequent tactile targets delivered to this hand. Effects of tactile attention on the processing of tactile events, as reflected by attentional modulations of somatosensory ERPs to tactile stimuli, were very similar for early blind and sighted participants, suggesting that the capacity to selectively process tactile information from one hand versus the other does not differ systematically between the blind and the sighted. ERPs measured during the cue–target interval revealed an anterior directing attention negativity (ADAN) that was present for the early blind group as well as for the sighted control group. In contrast, the subsequent posterior late direction attention negativity (LDAP) was absent in both groups. These results suggest that these two components reflect functionally distinct attentional control mechanisms which differ in their dependence on the availability of visually coded representations of external space

Analysis of molecular diversity, population structure and linkage disequilibrium in a worldwide survey of cultivated barley germplasm (Hordeum vulgare L.)

BACKGROUND: The goal of our study was a systematic survey of the molecular diversity in barley genetic resources. To this end 953 cultivated barley accessions originating from all inhabited continents except Australia were genotyped with 48 SSR markers. Molecular diversity was evaluated with routine statistics (allelic richness, gene diversity, allele frequency, heterozygosity and unique alleles), Principal Coordinate Analysis (PCoA), and analysis of genome-wide linkage disequilibrium. RESULTS: A genotyping database for 953 cultivated barley accessions profiled with 48 SSR markers was established. The PCoA revealed structuring of the barley population with regard to (i) geographical regions and (ii) agronomic traits. Geographic origin contributed most to the observed molecular diversity. Genome-wide linkage disequilibrium (LD) was estimated as squared correlation of allele frequencies (r(2)). The values of LD for barley were comparable to other plant species (conifers, poplar, maize). The pattern of intrachromosomal LD with distances between the genomic loci ranging from 1 to 150 cM revealed that in barley LD extended up to distances as long as 50 cM with r(2 )> 0.05, or up to 10 cM with r(2 )> 0.2. Few loci mapping to different chromosomes showed significant LD with r(2 )> 0.05. The number of loci in significant LD as well as the pattern of LD were clearly dependent on the population structure. The LD in the homogenous group of 207 European 2-rowed spring barleys compared to the highly structured worldwide barley population was increased in the number of loci pairs with r(2 )> 0.05 and had higher values of r(2), although the percentage of intrachromosomal loci pairs in significant LD based on P < 0.001 was 100% in the whole set of varieties, but only 45% in the subgroup of European 2-rowed spring barleys. The value of LD also varied depending on the polymorphism of the loci selected for genotyping. The 17 most polymorphic loci (PIC > 0.80) provided higher LD values as compared to 19 low polymorphic loci (PIC < 0.73) in both structured (all accessions) and non-structured (European 2-rowed spring varieties) barley populations. CONCLUSION: A global population of cultivated barley accessions was highly structured. Clustering highlighted the accessions with the same geographic origin, as well as accessions possessing similar agronomic characters. LD in barley extended up to 50 cM, and was strongly dependent on the population structure. The data on LD were summarized as a genome-wide LD map for barley

Relationship between sources and patterns of VOCs in indoor air

AbstractPeople spend most of their daytime in indoor environments. Their activities influence the composition of the indoor air by emitting volatile organic compounds (VOCs). The increasing number of different VOCs became the focus of attention in recent years as the question arises from the relationship between exposure to air pollutants and diseases. The present study of flats in Leipzig (Germany) is based on measurements of 60 different VOCs and is unique in the field of indoor air quality due to its enormous size of samples (n=2 242) and questionnaire data. The main purpose of our analysis was to identify the sources and patterns that characterize airborne VOCs in occupied flats. We combined two methods, principal components analysis (PCA) and non–negative matrix factorization (NMF), to assign compounds to their origin and to understand the coinstantaneous existence of several VOCs. PCA clustering provided a source apportionment and yielded 10 principal components (PCs) with an explained variance of 72%. However, real indoor air quality is often affected by combined sources. NMF reveals characteristic compositions of VOCs in indoor environments and emphasizes that constantly recurring structures are not single sources, but rather fusions of them, so called patterns. Interpreting these sources, we realized that homes were strongly influenced by ventilation, human activities, furnishings, natural processes (such as solar radiation) or their combinations. The very large set of samples and the combination with questionnaires applied on this comprehensive assessment of VOCs allows generalizing the results to homes in middle–scale cities with minor industrial pollution. As a conclusion, single VOC–dose–response relationships are inopportune for situations when indoor sources occur in combination. Further studies are necessary to assess associated health risks