Untersuchungen zur Produktion von Cyanobacterin, einem Toxin aus dem Cyanobakterium Scytonema hofmanni Ag.(UTEX1581): anwendungsbezogene und ökologische Aspekte

Vor dem Hintergrund der biotechnologischen Produktion des Cyanotoxins Cyanobacterin durch das Cyanobakterium Scytonema hofmanni (UTEX 1581) wurde der Einfluss der abiotischen Parameter Photonenflussdichte, pH-Wert, Temperatur, der Nährstoffkonzentrationen an Nitrat und Phospat sowie von Spurenelementen untersucht. Aus diesen Ergebnissen wurden Schlüsse hinsichtlich der Ökologie von Scytonema hofmanni als Bestandteil von Cyanobakteriengemeinschaften der Everglades (Florida, USA) gezogen. Es wurde eine neue Methode entwickelt, um die Cyanobacterinkonzentration in der Biomasse photometrisch im DMF-Extrakt in etwa 24 h zu quantifizieren. Cyanobacterin ist eine Allelochemikalie, deren Synthese wiederum durch Allelopathie beeinflusst wird. Cyanobacterin kann als biogenes Herbizid und als Co-Anitfoulant angewandt werden.The aim of the study was to investigate the biotechnical production of the cyanotoxin cyanobacterin by the cyanobacterium Scytonema hofmanni (UTEX 1581) under the influence of the following abiotic parameters: photon flux rate, pH, temperature, different nutrient concentrations nitrate and phosphate as well as of trace elements. Based on these data, the ecology of Scytonema hofmanni as part of a cyanobacterial community in the Everglades (Florida, USA) was concluded. A new rapid method was developed to quantify cyanobacterin in the biomass by photometric analysis of DMF-extracts within 24 h. Cyanobacterin exhibited allelochemical effects and its biosynthesis again is influenced by allelopathy. Cyanobacterin can be used as a natural herbizide and as a co-antifoulant

Emerging risks from ballast water treatment: The run-up to the International Ballast Water Management Convention

AbstractUptake and discharge of ballast water by ocean-going ships contribute to the worldwide spread of aquatic invasive species, with negative impacts on the environment, economies, and public health. The International Ballast Water Management Convention aims at a global answer. The agreed standards for ballast water discharge will require ballast water treatment. Systems based on various physical and/or chemical methods were developed for on-board installation and approved by the International Maritime Organization. Most common are combinations of high-performance filters with oxidizing chemicals or UV radiation. A well-known problem of oxidative water treatment is the formation of disinfection by-products, many of which show genotoxicity, carcinogenicity, or other long-term toxicity. In natural biota, genetic damages can affect reproductive success and ultimately impact biodiversity. The future exposure towards chemicals from ballast water treatment can only be estimated, based on land-based testing of treatment systems, mathematical models, and exposure scenarios. Systematic studies on the chemistry of oxidants in seawater are lacking, as are data about the background levels of disinfection by-products in the oceans and strategies for monitoring future developments. The international approval procedure of ballast water treatment systems compares the estimated exposure levels of individual substances with their experimental toxicity. While well established in many substance regulations, this approach is also criticised for its simplification, which may disregard critical aspects such as multiple exposures and long-term sub-lethal effects. Moreover, a truly holistic sustainability assessment would need to take into account factors beyond chemical hazards, e.g. energy consumption, air pollution or waste generation

Detektion av defekter med ett interkativt kodreviewverktyg baserat på visualisering och maskininlärning

Code review is often suggested as a means of improving code quality. Since humans are poor at repetitive tasks, some form of tool support is valuable. To that end we developed a prototype tool to illustrate the novel idea of applying machine learning (based on Normalised Compression Distance) to the problem of static analysis of source code. Since this tool learns by example, it is rivially programmer adaptable. As machine learning algorithms are notoriously difficult to understand operationally (they are opaque) we applied information visualisation to the results of the learner. In order to validate the approach we applied the prototype to source code from the open-source project Samba and from an industrial, telecom software system. Our results showed that the tool did indeed correctly find and classify problematic sections of code based on training examples

Detecting Defects with an Interactive Code Review Tool Based on Visualisation and Machine Learning

Code review is often suggested as a means of improving code quality. Since humans are poor at repetitive tasks, some form of tool support is valuable. To that end we developed a prototype tool to illustrate the novel idea of applying machine learning (based on Normalised Compression Distance) to the problem of static analysis of source code. Since this tool learns by example, it is rivially programmer adaptable. As machine learning algorithms are notoriously difficult to understand operationally (they are opaque) we applied information visualisation to the results of the learner. In order to validate the approach we applied the prototype to source code from the open-source project Samba and from an industrial, telecom software system. Our results showed that the tool did indeed correctly find and classify problematic sections of code based on training examples