Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Large Hadron Collider & Neutrino. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Hyperspectral phenotyping on the microscopic scale: towards automated characterization of plant-pathogen interactions

Abstract: The detection and characterization of resistance reactions of crop plants against fungal pathogens are essential to select resistant genotypes. In breeding practice phenotyping of plant genotypes is realized by time consuming and expensive visual rating. In this context hyperspectral imaging (HSI) is a promising non-invasive sensor technique in order to accelerate and to automate classical phenotyping methods. A hyperspectral microscope was established to determine spectral changes on the leaf and cellular level of barley (Hordeum vulgare) during resistance reactions against powdery mildew (Blumeria graminis f.sp. hordei, isolate K1). Experiments were conducted with near isogenic barley lines of cv. Ingrid, including the susceptible wild type (WT), mildew locus a 12 (Mla12 based resistance) and the resistant mildew locus o 3 (mlo3 based resistance), respectively. The reflection of inoculated and non-inoculated leaves was recorded daily with a hyperspectral linescanner in the visual (400 – 700 nm) and near infrared (700 – 1000 nm) range 3 to 14 days after inoculation. Data analysis showed no significant differences in spectral signatures between non-inoculated genotypes. Barley leaves of the near-isogenic genotypes, inoculated with B. graminis f.sp. hordei differed in the spectral reflectance over time, respectively. The susceptible genotypes (WT, Mla12) showed an increase in reflectance in the visible range according to symptom development. However, the spectral signature of the resistant mlo-genotype did not show significant changes over the experimental period. In addition, a recent data driven approach for automated discovery of disease specific signatures, which is based on a new representation of the data using Simplex Volume Maximization (SiVM) was applied. The automated approach - evaluated in only a fraction of time revealed results similar to the time and labor intensive manually assessed hyperspectral signatures. The new representation determined by SiVM was also used to generate intuitive and easy to interpretable summaries, e.g. fingerprints or traces of hyperspectral dynamics of the different genotypes. With this HSI based and data driven phenotyping approach an evaluation of host-pathogen interactions over time and a discrimination of barley genotypes differing in susceptibility to powdery mildew is possible.

Sensitivity by combination: immuno-PCR and related technologies.

Abstract: The versatility of immunoassays for the detection of antigens can be combined with the signal amplification power of nucleic acid amplification techniques in a broad range of innovative detection strategies. This review summarizes the spectrum of both, DNA-modification techniques used for assay enhancement and the resulting key applications. In particular, it focuses on the highly sensitive immuno-PCR (IPCR) method. This technique is based on chimeric conjugates of specific antibodies and nucleic acid molecules, the latter of which are used as markers to be amplified by PCR or related techniques for signal generation and read-out. Various strategies for the combination of antigen detection and nucleic acid amplification are discussed with regard to their laboratory analytic performance, including novel approaches to the conjugation of antibodies with DNA, and alternative pathways for signal amplification and detection. A critical assessment of advantages and drawbacks of these methods for a number of applications in clinical diagnostics and research is conducted. The examples include the detection of viral and bacterial antigens, tumor markers, toxins, pathogens, cytokines and other targets in different biological sample materials.

Nanomechanical Devices Based on DNA

Abstract: Biomolecular compounds, such as proteins and nucleic acids, which are evolutionary optimized, with respect to specificity of binding to their target structure as well as to functionality, for distinct biochemical transformation and translocation, are currently explored as building blocks in the ™bottom-up∫ self-assembly of nanometer-scale functional devices. [1] So far, applications include the organization of metal and semiconductor nanoclusters, [2] numerous bioana-lytical techniques, [1] as well as biomolecular electronics [3] and nanomechanical devices. While the development of the latter was, in past years, mainly focused on motor proteins, such as actin, kinesin, and myosin, [4] nowadays an increasing number of reports are being devoted to the construction of nano-mechanical devices from DNA. This biomolecule plays an outstanding role in the development of artificial biomolecular hybrid elements, since the specificity of simple AT and G-C base pairing as well as its robust physicochemical nature allows for the fabrication of nanostructured molecular scaffolding and surface architecture, [5] and to selectively position proteins, [6] inorganic colloidal components, [2] carbohydrates , [7] organometallics, [8] and reactive chemical compounds [9] on the nanometer length scale. Another interesting property of the DNA double helix is its intrinsic susceptibility to external stimuli mediated by small molecules or ions, which opens up ways to fabricate nano-mechanical devices. For example, the contour length and the flexibility of a DNA molecule can be effectively altered by use of intercalators, such as acridinium or ethidium bromide derivatives, which bind in between the stacked nucleobases of the double helix and thereby significantly increase the DNA contour length. [10] Seeman and co-workers made use of this phenomenon: They reported on the induced change in torque of a circular DNA molecule containing a partially mobile branched DNA junction on intercalation of ethidium bromide as a potential supercoiling motion for nanomechanical elements. More recently, the Seeman group established an elegant means to utilize electrostatic interaction of Co 3‡ ions for switching a DNA device comprised of two rigid DNA double-crossover motifs. The latter were covalently linked to each other by a short d(CG) 10 proto-Z sequence which is capable of changing its conformation from a right-handed B-to a left-handed Z-DNA double helix (Figure 1 A). [12] The conforma-tional change leads to a spatial separation of two fluorescent labels, attached to each of the two double-crossover moieties, which can be measured by fluorescence resonance energy transfer (FRET). In a different approach, the increase in concentration of …

Eliciting security requirements and tracing them to design: an integration of Common Criteria, heuristics, and UMLsec

Abstract: Building secure systems is difficult for many reasons. This paper deals with two of the main challenges: (i) the lack of security expertise in development teams and (ii) the inadequacy of existing methodologies to support developers who are not security experts. The security standard ISO 14508 Common Criteria (CC) together with secure design techniques such as UMLsec can provide the security expertise, knowledge, and guidelines that are needed. However, security expertise and guidelines are not stated explicitly in the CC. They are rather phrased in security domain terminology and difficult to understand for developers. This means that some general security and secure design expertise are required to fully take advantage of the CC and UMLsec. In addition, there is the problem of tracing security requirements and objectives into solution design, which is needed for proof of requirements fulfilment. This paper describes a security requirements engineering methodology called SecReq. SecReq combines three techniques: the CC, the heuristic requirements editor HeRA, and UMLsec. SecReq makes systematic use of the security engineering knowledge contained in the CC and UMLsec, as well as security-related heuristics in the HeRA tool. The integrated SecReq method supports early detection of security-related issues (HeRA), their systematic refinement guided by the CC, and the ability to trace security requirements into UML design models. A feedback loop helps reusing experience within SecReq and turns the approach into an iterative process for the secure system life-cycle, also in the presence of system evolution.