Non-uniformity issues and workarounds in bounded-size sampling

A variety of schemes have been proposed in the literature to speed up query processing and analytics by incrementally maintaining a bounded-size uniform sample from a dataset in the presence of a sequence of insertion, deletion, and update transactions. These algorithms vary according to whether the dataset is an ordinary set or a multiset and whether the transaction sequence consists only of insertions or can include deletions and updates. We report on subtle non-uniformity issues that we found in a number of these prior bounded-size sampling schemes, including some of our own. We provide workarounds that can avoid the non-uniformity problem; these workarounds are easy to implement and incur negligible additional cost. We also consider the impact of non-uniformity in practice and describe simple statistical tests that can help detect non-uniformity in new algorithms.     

Detection of UF resin on wood particles and in particleboards: potential of selected methods for practice-oriented offline detection

In the wood-based panel industry, controlling the manufacturing process is crucial for ensuring product quality, using resources efficiently and cutting production costs. One major aspect for the final quality of particleboards is the distribution of resin on particles within a board. This study deals with the comparison of techniques that can be used for a practice-oriented detection of urea formaldehyde resin within an industrial environment. Resin detection was carried out by staining the resin with visible and fluorescent dyes as well as by near infrared spectroscopic (NIR) in combination with CHN elemental analysis. Using the fluorescent dye Brilliant Sulphaflavine, resin as well as single resin droplets could be detected best. NIR measurements did not lead to coherent results and should be further improved, especially because of its potential for online detection.     

Charge transfer in thin films of donor–acceptor complexes studied by infrared spectroscopy

The degree of charge transfer in thin films of organic charge transfer (CT)-complexes, which are deposited via thermal evaporation, is examined via infrared-spectroscopy. We demonstrate a linear relationship between the shift in the excitation energy of the CN-stretching mode of CT-complexes with the acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the charge transfer. The measured correlation corresponds very well with DFT calculations. For Na-TCNQ we observe a splitting in the peak of the CN-stretching mode, which can be explained by the coupling of two modes and was confirmed by the calculations. In CT-complexes with partial charge transfer the appearance of an electronic excitation is demonstrated.     

White-light interferometric method for secure key distribution

A protocol for secure key distribution using classical light is proposed. The method relies on white-light interferometric measurements by one of the communicating parties and the random choice of delays by the other party. In this way, securely shared random keys are created, thereby enabling secure data transmission. In contrast to quantum key distribution, only classical waves are used. Single photons (and the practical problems associated with them) are avoided. The security of the method cannot be proven at the moment but different attacks are described and briefly analyzed.     

Micro- and nanostructured Al2O3 surfaces for controlled vascular endothelial and smooth muscle cell adhesion and proliferation

The effect of the micro- and nanotopography on vascular cell-surface interaction is investigated using nano- and microstructured Al₂O₃ as model substrate. Two different nanostructured Al₂O₃ surfaces composed of low density (LD) and high density (HD) nanowires (NWs) were synthesized by chemical vapour deposition (CVD) and commercially available microstructured Al₂O₃ plates were used for comparison. A clear diverging response of human umbilical vein endothelial cells (HUVEC) and human umbilical vein smooth muscle cells (HUVSMC) was observed on these nano- and microstructured surfaces. LD Al₂O₃ NWs seem to enhance the proliferation of HUVECs selectively. This selective control of the cell-surface interaction by topography may represent a key issue for the future stent material design.