Duality symmetry of N=4 Yang-Mills theory on T^3

We study the spectrum of BPS states in N=4 supersymmetric U(N) Yang-Mills theory. This theory has been proposed to describe M-theory on T^3 in the discrete light-cone formalism. We find that the degeneracy of irreducible BPS bound states in this model exhibits a (partially hidden) SL(5,Z) duality symmetry. Besides the electro-magnetic symmetry, this duality group also contains Nahm-like transformations that interchange the rank N of the gauge group with some of the magnetic or electric fluxes. In the M-theory interpretation, this mapping amounts to a reflection that interchanges the longitudinal direction with one of the transverse directions.Comment: 16 pages, Latex, no figures. Some eqns in section 4 on Nahm duality correcte

Yield reduction due to diseases and lodging and impact of input intensity on yield in variety trials in five cereal crops

Breeding of multi-resistant varieties to reduce yield loss due to disease damage and lodging, and reduction of input intensity are of high importance for a more sustainable cereal production. The aim of this study was to evaluate (i) yield reduction caused by diseases and lodging and (ii) impact of input intensity and soil fertility in cereal variety trials grown under two intensities. Intensity 2 was treated with and intensity 1 without fungicides and growth regulators. We applied multiple regression approaches based on mixed linear models. First, we estimated relative yield reduction in intensity 1 compared to intensity 2 as a function of severity scores of diseases and lodging. High yield reductions occurred in winter wheat and winter triticale, moderate in winter rye and winter barley and low in spring barley. The damage potential was highest for yellow rust, followed by brown rust, lodging and Septoria tritici blotch. Medium damage potential was identified for dwarf leaf rust and low for powdery mildew, Septoria nodorum blotch, Rhynchosporium as well as for stem and ear buckling. Second, differences in input intensity did not affect yield in intensity 2 across the range of nitrogen and fungicide application rates while higher yield occurred at higher growth regulator rates and soil fertility. Growth regulator was strongly related with higher yield in winter rye and winter barley, however in spring barley, a negative relation was found. Soil fertility showed the strongest yield impact in all crops

Drought impacts on tree root traits are linked to their decomposability and net carbon release

Root trait plasticity can facilitate plant adjustment to water shortages, but the impact of altered traits on belowground carbon (C) cycling is mostly unknown. While drought and nutrient availability can alter root morphological and chemical traits that may affect root decomposition, direct assessments of drought mediated changes on decomposability are not available. We exposed four tree species contrasting in drought stress tolerance and root traits to three dry-down and recovery periods (over 5 months after 11 months of growth in well-watered conditions) under high and low nutrient conditions. We then assessed early stage root decomposability in relation to their morphology and chemistry as well as implications for CO2 release when accounting for effects on root biomass. While each species showed a unique set of responses, drought generally reduced root diameter and increased nitrogen concentration. We found limited evidence that morphological responses to drought were counteracted by high nutrient supply. Results indicated that the degree of association between morphological and nutrient root trait responses to drought and decomposability varied with different species. However, across these contrasting woody species, drought-induced increases in nitrogen and phosphorus concentrations were associated with drought-induced increases in early stage root decomposability. When accounting for changes in root biomass, estimated overall C loss through root decomposition increased with drought stress. Our experimental results demonstrate that changes in tree root traits with drought can enhance C loss via root decomposition, and with other factors being equal, drought may potentially contribute to a positive feedback to climate change. Our findings contribute empirical evidence to help disentangle the multiple factors involved in root contribution to C balances at the ecosystem level

Identifying governance challenges in ecosystem services management – Conceptual considerations and comparison of global forest cases

Ecosystems around the world generate a wide range of services. Often, there are trade-offs in ecosystem service provision. Managing such trade-offs requires governance of interdependent action situations. We distinguished between (1) enhancing action situations where beneficiaries create, maintain, or improve an ESS and (2) appropriation action situations where actors subtract from a flow of ESS. We classified ESSs in order to identify focal action situations and link them to ESS governance types which are likely to strengthen sustainable ecosystem management. The classification is applied to six forest cases in Asia, Africa and Latin America. Our results confirm that ecosystem management, which more strongly supports the provision of public goods and common pool resources, is often under strong pressure to be transformed into systems that mainly provide private goods. This can be partly explained by incentive constellations in the action situations of public goods and common pool resources. Therefore, governance has to be adapted to specific ESSs. ESS governance needs to identify institutions which best fit to different ESSs and to harmonize them for all the ESSs provided by the system. Our approach helps to understand why institutions fail or succeed in maintaining ESSs

Witterungsextreme und ihre Bedeutung für die jährlichen Ertragsabweichungen von Winterweize

KlimafolgenFür die Landwirtschaft stellen Witterungsereignisse mit signifikanten Abweichungen von langjährigen Mittel eine große Herausforderung dar. Witterungsextreme wie Starkregen, Hitzeperioden während kritischer phänologischer Phasen wie beispielsweise der Blüte oder längere niederschlagsfreie Zeiten haben oftmals direkte Auswirkungen auf den Ertrag und die Qualität der Ernteprodukte. Durch den Klimawandel werden zudem die Wiederkehr von Extremereignissen und die Intensität von Witterungsereignissen beeinflusst. Die Bedeutung der Witterungsextreme für die jährlichen Ertragsschwankungen von Winterweizen wurde durch die Auswertung der Langzeitversuche des JKI in Dahnsdorf, Brandenburg untersucht. Die Klimadaten entstammen der Wetterstation auf dem Versuchsfeld und fehlende Daten sind durch Interpolation von umliegenden Klimastationen auf diesen Standort für die Zeit von 1993-2013 erzeugt worden. Während des Untersuchungszeitraums betrug die jährliche Durchschnittstemperatur 9.6°C und der Jahresniederschlag lag bei 587 mm. Die Anzahl aufeinanderfolgender Tage ohne Niederschlag (NCDWP) von April-September und die Temperatur >25°C (NHD) zur Blüte von Winterweizen im Zeitraum vom 1.-21.Juni in Kombination mit unterschiedlichen Pflanzenschutzstrategien wurde hinsichtlich der Bedeutung für die jährlichen Ertragsschwankungen analysiert. Sowohl bei den NCDWP als auch bei den NHD konnte für den Betrachtungszeitraum für die Werte oberhalb des 80%-igen Perzentils eine leichte Zunahme beider Extrema für diesen Standort gefunden werden (Zunahme von 5 auf 6 bei NHD und 14 auf 15 bei NCDWP). Eine Regressionsanalyse für den Zeitraum von 1996-2007 ergab für beide Extrema ertragsrelevante Auswirkungen auf die jährlichen Ertragsschwankungen. Hierbei zeigten die NHD eine deutlich stärkere ertragsrelevante Auswirkung als die NCDWP bei Winterweizen, abhängig von den jeweiligen Pflanzenschutzstrategien

Introducing an algal carbon-concentrating mechanism into higher plants: location and incorporation of key components.

Many eukaryotic green algae possess biophysical carbon-concentrating mechanisms (CCMs) that enhance photosynthetic efficiency and thus permit high growth rates at low CO2 concentrations. They are thus an attractive option for improving productivity in higher plants. In this study, the intracellular locations of ten CCM components in the unicellular green alga Chlamydomonas reinhardtii were confirmed. When expressed in tobacco, all of these components except chloroplastic carbonic anhydrases CAH3 and CAH6 had the same intracellular locations as in Chlamydomonas. CAH6 could be directed to the chloroplast by fusion to an Arabidopsis chloroplast transit peptide. Similarly, the putative inorganic carbon (Ci) transporter LCI1 was directed to the chloroplast from its native location on the plasma membrane. CCP1 and CCP2 proteins, putative Ci transporters previously reported to be in the chloroplast envelope, localized to mitochondria in both Chlamydomonas and tobacco, suggesting that the algal CCM model requires expansion to include a role for mitochondria. For the Ci transporters LCIA and HLA3, membrane location and Ci transport capacity were confirmed by heterologous expression and H(14) CO3 (-) uptake assays in Xenopus oocytes. Both were expressed in Arabidopsis resulting in growth comparable with that of wild-type plants. We conclude that CCM components from Chlamydomonas can be expressed both transiently (in tobacco) and stably (in Arabidopsis) and retargeted to appropriate locations in higher plant cells. As expression of individual Ci transporters did not enhance Arabidopsis growth, stacking of further CCM components will probably be required to achieve a significant increase in photosynthetic efficiency in this species

Continuity of care for patients with de novo metastatic cancer during the COVID-19 pandemic:A population-based observational study

During the COVID-19 pandemic recommendations were made to adapt cancer care. This population-based study aimed to investigate possible differences between the treatment of patients with metastatic cancer before and during the pandemic by comparing the initial treatments in five COVID-19 periods (weeks 1–12 2020: pre-COVID-19, weeks 12–20 2020: 1st peak, weeks 21–41 2020: recovery, weeks 42–53 2020: 2nd peak, weeks 1–20 2021: prolonged 2nd peak) with reference data from 2017 to 2019. The proportion of patients receiving different treatment modalities (chemotherapy, hormonal therapy, immunotherapy or targeted therapy, radiotherapy primary tumor, resection primary tumor, resection metastases) within 6 weeks of diagnosis and the time between diagnosis and first treatment were compared by period. In total, 74,208 patients were included. Overall, patients were more likely to receive treatments in the COVID-19 periods than in previous years. This mainly holds for hormone therapy, immunotherapy or targeted therapy and resection of metastases. Lower odds were observed for resection of the primary tumor during the recovery period (OR 0.87; 95% CI 0.77–0.99) and for radiotherapy on the primary tumor during the prolonged 2nd peak (OR 0.84; 95% CI 0.72–0.98). The time from diagnosis to the start of first treatment was shorter, mainly during the 1st peak (average 5 days, p &lt;.001). These findings show that during the first 1.5 years of the COVID-19 pandemic, there were only minor changes in the initial treatment of metastatic cancer. Remarkably, time from diagnosis to first treatment was shorter. Overall, the results suggest continuity of care for patients with metastatic cancer during the pandemic.</p

Live Imaging of Xwnt5A-ROR2 Complexes

Secreted molecules of the Wnt family regulate key decisions in embryogenesis and adult tissue homeostasis by activating a complex network of Wnt signaling pathways. Although the different branches of Wnt signaling have been studied for more than 25 years, fluorophore tagged constructs for live cell imaging of Wnt molecules activating the Wnt/β-catenin pathway have become available only recently. We have generated a fluorophore tagged Wnt construct of the Xenopus Wnt5a protein (Xwnt5A) with the enhanced green fluorescent protein (EGFP), Xwnt5A-EGFP. This construct activates non-canonical Wnt pathways in an endocytosis dependent manner and is capable of compensating for the loss of endogenous Xwnt5A in Xenopus embryos. Strikingly, non-canonical Wnt pathway activation was restricted to short-range signaling while an inhibitory effect was observed in transwell cell cultures taken as long-range signaling model sytem. We used our Xwnt5A-EGFP construct to analyze in vivo binding of Wnt5A to its co-receptor ROR2 on the microscopic and on the molecular level. On the microscopic level, Xwnt5A-EGFP clusters in the membrane and recruits ROR2-mCherry to these clusters. Applying dual-colour dual-focus line-scanning fluorescence correlation spectroscopy on dorsal marginal zone explants, we identified membrane tethered Xwnt5A-EGFP molecules binding to ROR2-mCherry molecules. Our data favour a model, in which membrane-tethered Wnt-5A recruits ROR2 to form large ligand/receptor clusters and signals in an endocytosis-dependent manner