Dynamic Ordered Sets with Exponential Search Trees

We introduce exponential search trees as a novel technique for converting static polynomial space search structures for ordered sets into fully-dynamic linear space data structures. This leads to an optimal bound of O(sqrt(log n/loglog n)) for searching and updating a dynamic set of n integer keys in linear space. Here searching an integer y means finding the maximum key in the set which is smaller than or equal to y. This problem is equivalent to the standard text book problem of maintaining an ordered set (see, e.g., Cormen, Leiserson, Rivest, and Stein: Introduction to Algorithms, 2nd ed., MIT Press, 2001). The best previous deterministic linear space bound was O(log n/loglog n) due Fredman and Willard from STOC 1990. No better deterministic search bound was known using polynomial space. We also get the following worst-case linear space trade-offs between the number n, the word length w, and the maximal key U < 2^w: O(min{loglog n+log n/log w, (loglog n)(loglog U)/(logloglog U)}). These trade-offs are, however, not likely to be optimal. Our results are generalized to finger searching and string searching, providing optimal results for both in terms of n.Comment: Revision corrects some typoes and state things better for applications in subsequent paper

Implementation of the Functional Mock-up Interface in Matlab and Simulink

New products on the market are likely to be simulated in a computer sometime during the development process. The environment for which the physical model of the product is developed may not always be the optimal for control simulations of the model. To be able to export models from one environment to another a common model definition must be defined. The Functional Mock-up Interface, FMI, provides such a model definition and makes it possible to incorporate models from different environments together. In this thesis we will witness a successful implementation of the interface for model exchange, FMI, into the well known MATLAB and Simulink environment. Simulink is widely used in industry to develop control systems but not that used for physical modelling. It is therefore of great interest to be able to simulate models created from other physical modelling environments in to Simulink. A block is developed in Simulink and a user interface in MATLAB such that models created according to the FMI standard can be simulated. The FMI is a standard for solving ODEs with events. The thesis discusses the most essential parts of the FMI standard. Events may be discontinuities that the ODE solver needs to take special care of and is therefore discussed in more detail. In Simulink an S-function block is used with a GUI developed for the user to easily configure the model. The MATLAB interface is developed using MEX functions and is discussed based on how MATLAB's ODE solvers can be used to simulate a model. MEX functions are MATLAB's way to incorporate C, C++ and Fortran code. The FMI standard models consists of DLL functions that enforce the use of MEX functions.The implementations are verified to be correct by comparison of simulation results from different environments such as Dymola and JModelica.org. A comparison of simulation times and the number of function evaluations are also done where we can see that the S-function and the MEX interface performs on a similar level as the other simulation environments

Wage growth dispersion across the euro area countries - some stylised facts

This study presents some stylised facts on wage growth differentials across the euro area countries in the years before and in the first eight years after the introduction of Economic and Monetary Union (EMU) in 1999. The study shows that wage growth dispersion, i.e. the degree of difference in wage growth at a given point in time, has been on a clear downward trend since the early 1980s. However, wage growth dispersion across the euro area countries still appears to be higher than the degree of wage growth dispersion within West Germany, the United States, Italy and Spain. Differences in wage growth rates between individual euro area countries and the euro area in the years before and in the first eight years after the introduction of EMU appear to be positively related to the respective differences between their Harmonised Index of Consumer Prices (HICP) inflation and average HICP inflation in the euro area. Conversely, relative wage growth differentials across euro area countries have been somewhat unrelated to relative productivity growth differentials. Some countries combine positive wage growth differentials and negative productivity growth differentials vis-à-vis the euro area average over an extended period – and hence positive unit labour cost growth differentials. These countries run the risk of accumulating competitiveness losses and it is therefore a challenge to ensure that the necessary adjustment mechanisms operate fully, in the sense that wage developments are sufficiently flexible and reflect productivity developments. Wage growth persistence within individual euro area countries – largely reflecting inflation persistence and certain institutional factors – might also have contributed somewhat to wage growth differentials across the euro area countries. Moreover, wage level convergence has also played a role in explaining wage growth patterns in the 1980s and the 1990s. However, since 1999, the link between the initial compensation level and the subsequent growth rate of compensation per employee appears barely significant. The study also shows a limited co-movement of wage growth across countries, even in the context of a high degree of business cycle synchronisation seen in the last few years. This suggests that the impact on wage growth of country-specific developments across euro area countries has been larger than the impact of common cyclical developments and external shocks. This could reflect the normal and desirable working of adjustment mechanisms, which – in an optimally functioning currency union with synchronised business cycles – would take place via price and cost and wage developments. On the other hand, structural impediments, for example a relatively low degree of openness in domestically-oriented sectors in some countries, might prevent a stronger link between the degree of synchronisation of wage growth rates and business cycles. JEL Classification: E24, E31, C10.Cross-country wage dispersion, wage and productivity levels across countries and sectors.

Predictability modulates the affective and sensory-discriminative neural processing of pain

Knowing what is going to happen next, that is, the capacity to predict upcoming events, modulates the extent to which aversive stimuli induce stress and anxiety. We explored this issue by manipulating the temporal predictability of aversive events by means of a visual cue, which was either correlated or uncorrelated with pain stimuli (electric shocks). Subjects reported lower levels of anxiety, negative valence and pain intensity when shocks were predictable. In addition to attenuate focus on danger, predictability allows for correct temporal estimation of, and selective attention to, the sensory input. With functional magnetic resonance imaging, we found that predictability was related to enhanced activity in relevant sensory-discriminative processing areas, such as the primary and secondary sensory cortex and posterior insula. In contrast, the unpredictable more aversive context was correlated to brain activity in the anterior insula and the orbitofrontal cortex, areas associated with affective pain processing. This context also prompted increased activity in the posterior parietal cortex and lateral prefrontal cortex that we attribute to enhanced alertness and sustained attention during unpredictability. (c) 2006 Elsevier Inc. All rights reserved.This study was supported by grants from The Swedish Research Council (2003-5810), The family Hedlund Foundation and Karolinska Institutet. The project was finished in the context of Stockholm Brain Institute.info:eu-repo/semantics/publishedVersio

Marginal Folate Deficiency as a Possible Cause of Hyperhomocysteinaemia in Stroke Patients

Peer Reviewe

Fusion trees can be implemented with AC0 instructions only

AbstractAddressing a problem of Fredman and Willard, we implement fusion trees in deterministic linear space using AC0 instructions only. More precisely, we show that a subset of {0,…,2w - 1} of size n can be maintained using linear space under insertion, deletion, predecessor, and successor queries, with O(log nlog log n) amortized time per operation on a RAM with word size w, where the only computational instructions allowed on the RAM are functions in AC0. The AC0 instructions used are not all available on today's computers

Valuation of small and multiple health risks: A critical analysis of SP data applied to food and water safety

This study elicits individual preferences for reducing morbidity and mortality risk in the context of an infectious disease (campylobacter) using choice experiments. Respondents are in the survey asked to choose between different policies that, in addition to the two health risks, also vary with respect to source of disease being targeted (food or water), when the policy takes place (in time), and the monetary cost. Our results in our baseline model are in line with expectations; respondents prefer the benefits of the program sooner than later, programs that reduce both the mortality and morbidity risk, and less costly programs. Moreover, our results suggest that respondents prefer water- compared with food-safety programs. However, a main objective of this study is to examine scope sensitivity of mortality risk reductions using a novel approach. Our results from a split-sample design suggest that the value of the mortality risk reduction, defined as the value of a statistical life, is SEK 3 177 (USD 483 million) and SEK 50 million (USD 8 million), respectively, in our two sub-samples. This result cast doubt on the standard scope sensitivity tests in choice experiments, and the results also cast doubt on the validity and reliability of VSL estimates based on stated preference (and revealed preference) studies in general. This is important due to the large empirical literature on non-market evaluation and the elicited values’ central role in policy making, such as benefit-cost analysis