Verification of Sigmoidal Artificial Neural Networks using iSAT

This paper presents an approach for verifying the behaviour of nonlinear Artificial Neural Networks (ANNs) found in cyber-physical safety-critical systems. We implement a dedicated interval constraint propagator for the sigmoid function into the SMT solver iSAT and compare this approach with a compositional approach encoding the sigmoid function by basic arithmetic features available in iSAT and an approximating approach. Our experimental results show that the dedicated and the compositional approach clearly outperform the approximating approach. Throughout all our benchmarks, the dedicated approach showed an equal or better performance compared to the compositional approach.Comment: In Proceedings SNR 2021, arXiv:2207.0439

Modulation of the Major Paths of Carbon in Photorespiratory Mutants of Synechocystis

Background: Recent studies using transcript and metabolite profiles of wild-type and gene deletion mutants revealed that photorespiratory pathways are essential for the growth of Synechocystis sp. PCC 6803 under atmospheric conditions. Pool size changes of primary metabolites, such as glycine and glycolate, indicated a link to photorespiration. Methodology/Principal Findings: The C-13 labelling kinetics of primary metabolites were analysed in photoautotrophically grown cultures of Synechocystis sp. PCC 6803 by gas chromatography-mass spectrometry (GC-MS) to demonstrate the link with photorespiration. Cells pre-acclimated to high CO2 (5%, HC) or limited CO2 (0.035%, LC) conditions were pulse-labelled under very high (2% w/w) C-13-NaHCO3 (VHC) conditions followed by treatment with ambient C-12 at HC and LC conditions, respectively. The C-13 enrichment, relative changes in pool size, and C-13 flux of selected metabolites were evaluated. We demonstrate two major paths of CO2 assimilation via Rubisco in Synechocystis, i.e., from 3PGA via PEP to aspartate, malate and citrate or, to a lesser extent, from 3PGA via glucose-6-phosphate to sucrose. The results reveal evidence of carbon channelling from 3PGA to the PEP pool. Furthermore, C-13 labelling of glycolate was observed under conditions thought to suppress photorespiration. Using the glycolate-accumulating Delta glcD1 mutant, we demonstrate enhanced C-13 partitioning into the glycolate pool under conditions favouring photorespiration and enhanced C-13 partitioning into the glycine pool of the glycine-accumulating Delta gcvT mutant. Under LC conditions, the photorespiratory mutants Delta glcD1 and Delta gcvT showed enhanced activity of the additional carbon-fixing PEP carboxylase pathway. Conclusions/Significance: With our approach of non-steady-state C-13 labelling and analysis of metabolite pool sizes with respective C-13 enrichments, we identify the use and modulation of major pathways of carbon assimilation in Synechocystis in the presence of high and low inorganic carbon supplies

Analyseergebnisse zum Gebäudebestand in Deutschland auf der Grundlage von Geobasisdaten

Seit 2010 werden die Geobasisprodukte „Amtliche Hausumringe“ und „Amtliche Hauskoordinaten“ (auch georeferenzierte Adressdaten genannt) – geometrische Teilauszüge der Automatisierten Liegenschaftskarte (ALK) – von der Zentralen Stelle für Hauskoordinaten, Hausumringe und 3D-Gebäudemodelle (ZSHH) der Bezirksregierung Köln für länderübergreifende oder bundesweite Untersuchungen angeboten. Erstmals sind dadurch umfassendere Untersuchungen zum deutschen Gebäudebestand möglich und Ausdifferenzierungen nach Menge, geometrischer Eigenschaften (u. a. Gebäudetyp) sowie seiner Nutzung durchführbar. Das Analysepotenzial ist aber noch weitaus größer, da sowohl auf administrativer Ebene als auch auf Rasterebene räumliche Muster für unterschiedliche thematische Fragestellungen abbildbar werden. Das raumbezogene Informationsinstrument Monitor der Siedlungs- und Freiraumentwicklung (IÖR-Monitor) ist eine wissenschaftliche Dienstleistung des Leibniz-Instituts für ökologische Raumentwicklung und stellt seit 2012 auch Gebäudeindikatoren auf Grundlage dieser Katasterdaten bereit. In diesem Beitrag werden dazu erste Arbeitsergebnisse vorgestellt

Potassium uptake in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 mainly depends on a Ktr-like system encoded by slr1509 (ntpJ)

AbstractThe molecular basis of potassium uptake in cyanobacteria has not been elucidated. However, genes known from other bacteria to encode potassium transporters can be identified in the genome of Synechocystis sp. strain PCC 6803. Mutants defective in kdpA and ntpJ were generated and characterized to address the role of the Kdp and KtrAB systems in this strain. KtrAB is crucial for K+ uptake, as the ΔntpJ mutant shows slowed growth, slowed potassium uptake kinetics, and increased salt sensitivity. The ΔkdpA mutant has the same phenotype as the wild type even at limiting potassium, but a ΔkdpAΔntpJ double mutant is not viable, indicating a role of Kdp for potassium uptake when the Ktr system is not functioning

Waveguide-pumping gain guided index antiguided fiber laser

Methods, systems and devices for a waveguide pumping gain guided index antiguided fiber laser having a fiber selected for a refractive index crossover at a wavelength between a pump wavelength and a laser emission wavelength. A waveguide pumping system pumps a light having a pump wavelength into the fiber allowing a laser light to be captured by a gain guided process in the core while the pump light, propagating in the cladding is coupled to the core. The fiber selection includes selecting a fiber with a cladding material having a refractive index less than a core material refractive index for a pump wavelength and a core refractive index at the laser emission wavelength is less than the cladding refractive index at the same laser emission wavelength to allow the pump light to propagate through the cladding as a conventional wave guided fiber laser, white the laser emission is captured within the core as an index antiguided, gain guided wave

Waveguide-Pumping Gain-Guided Index Anti Guided Fiber Lasers

Methods, systems and devices for a waveguide pumping gain guided index antiguided fiber laser having a fiber selected for a refractive index crossover at a wavelength between a pump wavelength and a laser emission wavelength. A waveguide pumping system pumps a light having a pump wavelength into the fiber allowing a laser light to be captured by a gain guided process in the core while the pump light, propagating in the cladding is coupled to the core. The fiber selection includes selecting a fiber with a cladding material having a refractive index less than a core material refractive index for a pump wavelength and a core refractive index at the laser emission wavelength is less than the cladding refractive index at the same laser emission wavelength to allow the pump light to propagate through the cladding as a conventional wave guided fiber laser, while the laser emission is captured within the core as an index antiguided, gain guided wave

The Synechocystis sp. PCC 6803 Genome Encodes Up to Four 2-Phosphoglycolate Phosphatases

Photorespiratory phosphoglycolate (2PG) metabolism is essential for cyanobacteria, algae, and plants. The first enzyme of the pathway, 2PG phosphatase (PGPase), is known from plants and algae but was scarcely investigated in cyanobacteria. In silico analysis revealed four candidate genes (slr0458, slr0586, sll1349, and slr1762) in the genome of the model cyanobacterium Synechocystis sp. PCC 6803 that all belong to the 2-haloacid dehalogenase (HAD) superfamily and could possibly encode PGPase proteins. However, in contrast to known algal and plant PGPases, the putative cyanobacterial PGPases belong to another HAD subfamily implying that PGPases in eukaryotic phototrophs did not originate from cyanobacterial PGPases. To verify their function, these four genes were inactivated both individually and in combination. A mild high-CO2-requiring (HCR) growth phenotype typical for photorespiratory mutants was observed only in Δsll1349. Combinatorial inactivation enhanced the HCR phenotype in specific double and triple mutants. Heterologous expression of the putative cyanobacterial PGPases in E. coli led to higher PGPase activities in crude cell extracts, but only the purified Slr0458 protein showed PGPase activity. Hence, we propose that a consortium of up to four photorespiratory PGPases may initiate photorespiratory 2PG metabolism in Synechocystis. We suggest that redundancy of this essential enzyme activity could be related to the highly adaptive lifestyle of cyanobacteria such as Synechocystis sp. PCC 6803, which allows them to grow under very diverse conditions