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51.
KeeLoq is a lightweight block cipher with a 32-bit block size and a 64-bit key. Despite its short key size, it is used in remote keyless entry systems and other wireless authentication applications. For example, there are indications that authentication protocols based on KeeLoq are used, or were used by various car manufacturers in anti-theft mechanisms. This paper presents a practical key recovery attack against KeeLoq that requires 216 known plaintexts and has a time complexity of 244.5 KeeLoq encryptions. It is based on the principle of slide attacks and a novel approach to meet-in-the-middle attacks.  相似文献   
52.
This paper contributes to process studies on organizational creativity by developing two competing research agendas. The first perspective, the ‘becoming’ view, depicts creativity as a constant flow of activity that crystallizes every once in a while in unpredictable moments of creativity. The second perspective, the ‘practice’ view, understands creativity as a practised social process, in which structures play the important role of both enabling and constraining individual agents in pursuing creativity as a collective phenomenon. We compare and contrast these two theoretical perspectives, which are based on different process ontologies, and discuss their methodological implications. We argue that the practice perspective offers particular promise, because it allows us to address the important yet paradoxical question of how creativity may be organized and managed.  相似文献   
53.
We report on the synthesis of SnO2 and CuO nanowires and their application as gas sensing components. The fabrication of SnO2 and CuO single nanowire devices by optical and electron beam lithography is described, and sensing performance to the toxic gas carbon monoxide is demonstrated. We briefly present the development of CMOS fabricated micro-hotplates as platforms for gas sensors and show our approach for nanowire implementation. Finally, we demonstrate a fully CMOS integrated CuO multi nanowire device and present our roadmap for a fully integrated multi-parameter smart sensor device which could be implemented as safety feature in smart phones.  相似文献   
54.
This paper comprises a simplified method for the determination of polychlorinated biphenyls (PCBs) in food and feedingstuffs. The method includes a cold column extraction step, a simple clean-up with concentrated sulfuric acid, and a final determination of the PCBs using gas chromatography-mass spectrometry (GC/MS). An in-house validation study was performed to establish method performance characteristics such as decision limit, detection capability, trueness and precision of the method. To determine these characteristics both certified reference materials and spiked samples were utilized. The decision limit and the detection capability of the individual PCB congeners in food were 2 ng/g and 3 ng/g fat, respectively, while corresponding figures for feedingstuffs were 7 ng/g and 9 ng/g fat, respectively. The coefficient of variation (CV) varied from 2% to 5% for food on the 10 ng/g fat level and from 2% to 6% for feedingstuffs on the 25 ng/g fat level. The recoveries of the individual PCB congeners varied from 88% to 107%, indicating good correspondence with internationally recognized criteria for the performance characteristics of analytical methods. The robustness of the method was investigated by employing a factorial design methodology to determine the influence of six experimental factors on the results of the analysis. This clearly demonstrated that the method is fit for surveillance of PCBs in food and feedingstuffs, even though some care has to be taken with the solvent volume during the cold column extraction step as well as the addition of the standard to the sample. Additionally, the investigation clearly demonstrates that in-house validation approaches may be used for determination of the overall performance of analytical methods.  相似文献   
55.
The free-radical scavenging activity of cocoa samples subjected to different roasting treatments has been determined. The samples (raw, pre-roasted and roasted) were separated into four molecular weight fractions per sample (>30, 30–10, 10–5, and <5 kDa). The free-radical scavenging activity was determined with the DPPH (1,1-dipheny-2-picrylhydrazyl), and ABTS•+ [2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] free-radical scavenging assays for all samples. Both tests were compared in terms of sensitivity and measurement precision, at different reaction times. Comparing the results from each test, the free-radical scavenging activity trends were similar for each fraction but with notable differences in the sensitivity of the assays. Analysis of the concentration of reducing substances, such as water soluble phenolics, melanoidins, carbohydrates, etc, in these fractions by the photometric Folin–Ciocalteu assay, showed a similar pattern to the free-radical scavenging activity trend. Moreover, this comparison showed that there were significantly (P < 0.05) more reducing substances and free-radical scavenging activity in the 10–5 kDa roasted cocoa bean fraction.  相似文献   
56.
57.
In this paper a unified methodology is presented for the modelling of the evolution of road safety in 30 European countries. For each country, annual data of the best available exposure indicator and of the number of fatalities were simultaneously analysed with the bivariate latent risk time series model. This model is based on the assumption that the amount of exposure and the number of fatalities are intrinsically related. It captures the dynamic evolution in the fatalities as the product of the dynamic evolution in two latent trends: the trend in the fatality risk and the trend in the exposure to that risk. Before applying the latent risk model to the different countries it was first investigated and tested whether the exposure indicator at hand and the fatalities in each country were in fact related at all. If they were, the latent risk model was applied to that country; if not, a univariate local linear trend model was applied to the fatalities series only, unless the latent risk time series model was found to yield better forecasts than the univariate local linear trend model. In either case, the temporal structure of the unobserved components of the optimal model was established, and structural breaks in the trends related to external events were identified and captured by adding intervention variables to the appropriate components of the model. As a final step, for each country the optimally modelled developments were projected into the future, thus yielding forecasts for the number of fatalities up to and including 2020.  相似文献   
58.
The increasing demand for high quality gluten-free (GF) bread, clean labels and natural products is raising the need for new approaches in GF bread-making. Sourdough is the foremost fermentation used for baking purposes and it has been proven to be ideal for improving the texture, palatability, aroma, shelf life and nutritional value of wheat and rye breads. These characteristic features derive from the complex metabolic activities of the sourdough-resident lactic acid bacteria and yeasts, e.g. acidification, production of exopolysaccharides, proteolytic- amylolytic- and phytase activity, and production of antimicrobial substances. These effects have been extensively studied and well described for traditional baking, whereas little is known about the role of sourdough in GF baking. Yet, the microbiological and qualitative characterisation of local GF fermented products indicate an overlap with the microbiota of wheat/rye fermentation and suggest that the positive metabolic activities of the sourdough microbiota are still retained during fermentation of GF crops. Thus, the use of sourdough in GF baking may be the new frontier for improving the quality, safety and acceptability of GF bread.  相似文献   
59.
This research examined whether people can accurately predict the risk preferences of others. Three experiments featuring different designs revealed a systematic bias: that participants predicted others to be more risk seeking than themselves in risky choices, regardless of whether the choices were between options with negative outcomes or with positive outcomes. This self–others discrepancy persisted even if a monetary incentive was offered for accurate prediction. However, this discrepancy occurred only if the target of prediction was abstract and vanished if the target was vivid. A risk-as-feelings hypothesis was introduced to explain these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
60.
A videokeratoscope based on the imaging of a gridlike pattern is introduced. Unlike conventional videokeratoscopes that rely on Placido disks, the new measurement principle allows an exact reconstruction of the surface and the display of fine details. The experimental instrument was tested on precision glass spheres; the maximum error of the height data was less than 3 microm. The sensitivity and the potential to resolve fine details were demonstrated with irregular surfaces of specially prepared contact lenses. Structures with height deviations of 0.1 microm are well identifiable. The eyes of 18 individuals were investigated, and fine structures were found on these cornea surfaces. Conventional videokeratoscopes do not resolve such detail.  相似文献   
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