High-efficiency thermoluminescent detectors for measuring the absorbed ionizing radiation dose in the environment

A study has been conducted with the goal of comparing the characteristics of TLD-K detectors based on sodium silicate ceramics to the characteristics of monocrystalline lithium fluoride detectors that contain traces of titanium and magnesium (TLD-100), as well as anion-defected aluminum oxide (TLD-500), which are widely used in thermoluminescent dosimetry. Because they are soil-equivalent, SiO₂ detectors are well suited for measuring the absorbed radiation dose in soils. The results of the comparison indicate that TLD-K detectors are preferable to LiF detectors in environmental applications due to the better uniformity of the detector sensitivity in a batch, the wider range of measurable doses, and the lower threshold in determining small doses.     

Wear behaviour of α- and α/β-SiAlON ceramics stabilized with Nd2O3 and Y2O3

α- and α/β-SiAlON compositions, doped with Y₂O₃ or Nd₂O₃, were densified by gas pressure sintering (GPS). The wear and mechanical properties of the materials were investigated and compared to β-Si₃N₄ materials. Microstructure evolution and its change with composition as well as the influence of the microstructural changes on the mechanical and tribological properties were reported. Wear tests were performed using a tribometer with ball-on-plate geometry in reciprocating sliding contact under dry condition. It was observed that α/β-SiAlON compositions, doped with Y₂O₃, have better wear properties in comparison to α-SiAlON and β-Si₃N₄ samples. Field emission scanning electron microscopy (FESEM) was used to analyse the worn surfaces after wear tests. The results showed that α/β-SiAlON and β-Si₃N₄ materials have different wear behaviour.     

Pattern storage and processing in attractor networks with short-time synaptic dynamics

Neurophysiological experiments show that the strength of synaptic connections can undergo substantial changes on a short time scale. These changes depend on the history of the presynaptic input. Using mean-field techniques, we study how short-time dynamics of synaptic connections influence the performance of attractor neural networks in terms of their memory capacity and capability to process external signals. For binary discrete-time as well as for firing rate continuous-time neural networks, the fixed points of the network dynamics are shown to be unaffected by synaptic dynamics. However, the stability of patterns changes considerably. Synaptic depression turns out to reduce the storage capacity. On the other hand, synaptic depression is shown to be advantageous for processing of pattern sequences. The analytical results on stability, size of the basins of attraction and on the switching between patterns are complemented by numerical simulations.     

用于AMLCD微显示的新型驱动

新型交流耦合结构使低功耗近眼微显示器使用3.3V供电的CMOS电路成为可能。     

Security requirement analysis of business processes

Economic globalization leads to complex decentralized company structures calling for the extensive use of distributed IT-systems. The business processes of a company have to reflect these changes of infrastructure. In particular, due to new electronic applications and the inclusion of a higher number of—potentially unknown—persons, the business processes are more vulnerable against malicious attacks than traditional processes. Thus, a business should undergo a security analysis. Here, the vulnerabilities of the business process are recognized, the risks resulting from the vulnerabilities are calculated, and suitable safeguards reducing the vulnerabilities are selected. Unfortunately, a security analysis tends to be complex and affords expensive security expert support. In order to reduce the expense and to enable domain experts with in-depth insight in business processes but with limited knowledge about security to develop secure business processes, we developed the framework MoSS_BP facilitating the handling of business process security requirements from their specification to their realization. In particular, MoSS _BP provides graphical concepts to specify security requirements, repositories of various mechanisms enforcing the security requirements, and a collection of reference models and case studies enabling the modification of the business processes. In this paper, the MoSS _BP -framework is presented. Additionally, we introduce a tool supporting the MoSS_BP-related security analysis of business processes and the incorporation of safeguards. This tool is based on object-oriented process models and acts with graph rewrite systems. Finally, we clarify the application of the MoSS_BP-framework by means of a business process for tender-handling which is provided by anonymity-preserving safeguards. Peter Herrmann studied computer science at the University of Karlsruhe, Germany (diploma in 1990). Afterwards, he worked as a Ph.D. student (doctorate in 1997) and postdoctoral researcher in the Computer Networks and Distributed Systems Group of the Computer Science Department at the University of Dortmund, Germany. Since 2005 he is a full professor for formal methods at the Department for Telematics of the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway. His research interests include the formal-based development of networked systems and the engineering of distributed services. Moreover, he is interested in security and trust aspects of component structured distributed software. Gaby Herrmann studied computer science at the University of Karlsruhe, Germany (diploma in 1991). Afterwards, she worked as a researcher in the Communication Group and the Information Systems Group at University of Duisburg-Essen (Doctorate in 2001, topic: security of business processes). Since 2000 she works as executive secretary at the Department of Economics, Business Studies and Computer Sciences at the same university.     

Penalty Approximation for Dynamical Systems Submitted to Multiple Non-Smooth Constraints

We consider discrete mechanical systems subject to perfect unilateral constraints. Moreau's impact law uses the decomposition of the velocity on the normaland tangent cones to the set of admissible positions at the impact point, and it iswell-known that this gives the only possible rule in the case of a singleperfect unilateral constraint. In the multi-constraint case, there areother possible energetically and geometrically consistant impact laws. Weshow here that in a number of cases, the limiting behavior of impact asits rigidity tends to infinity is given by Moreau's rule, i.e., in a more mathematical language, we justify this impact law by a penalty approach.First we describe the penalty method, then we apply it to amulti-constraint model problem. We choose an overdamped approximationand we obtain Moreau's rule for inelastic shocks in the limit. Finally,we present the computational drawbacks of the penalty method.     

Spatial impulse response of lithographic infrared antennas

We present measurements of the spatial response of infrared dipole and bow-tie lithographic antennas. Focused 10.6-mum radiation was scanned in two dimensions across the receiving area of each antenna. Deconvolution of the beam profile allowed the spatial response to be measured. The in-plane width of the antenna's spatial response extends approximately one dielectric wavelength beyond the metallic structure. Determination of an antenna's spatial response is important for several reasons. The power collected by the antenna can be calculated, if the collection area and the input irradiance (watts per square centimeter) are known. The actual power collected by the antenna is required for computation of responsivity and noise-equivalent power. In addition, the spatial response provides insight into the current-wave modes that propagate on an antenna and the nature of the fringe fields that exist in the adjacent dielectric.     

The NH2 terminus of titin spans the Z-disc: its interaction with a novel 19-kD ligand (T-cap) is required for sarcomeric integrity

Titin is a giant elastic protein in vertebrate striated muscles with an unprecedented molecular mass of 3-4 megadaltons. Single molecules of titin extend from the Z-line to the M-line. Here, we define the molecular layout of titin within the Z-line; the most NH2-terminal 30 kD of titin is located at the periphery of the Z-line at the border of the adjacent sarcomere, whereas the subsequent 60 kD of titin spans the entire width of the Z-line. In vitro binding studies reveal that mammalian titins have at least four potential binding sites for alpha-actinin within their Z-line spanning region. Titin filaments may specify Z-line width and internal structure by varying the length of their NH2-terminal overlap and number of alpha-actinin binding sites that serve to cross-link the titin and thin filaments. Furthermore, we demonstrate that the NH2-terminal titin Ig repeats Z1 and Z2 in the periphery of the Z-line bind to a novel 19-kD protein, referred to as titin-cap. Using dominant-negative approaches in cardiac myocytes, both the titin Z1-Z2 domains and titin-cap are shown to be required for the structural integrity of sarcomeres, suggesting that their interaction is critical in titin filament-regulated sarcomeric assembly.