Luminescence dates of the Iron Age cemetery at Møllegårdsmarken, Fyn, Denmark

The Iron Age cemetery at Møllegårdsmarken on the island of Funen is described briefly and the principle of luminescence dating is outlined. Dates for a number of cremation urns and for a potsherd found on a road running close to the site are presented. The dating was carried out with the OSL method SARA applied to quartz

A Quantitative Characterization of Weighted Kripke Structures in Temporal Logic

We extend the usual notion of Kripke structures with a weighted transition relation and generalize the classical Boolean interpretation of CTL to a map which assigns to states and temporal formulae a real-valued distance describing the degree of satisfaction. We describe a general approach to obtaining quantitative interpretations for a generic extension of the CTL syntax and show that, for one such interpretation, the logic is both adequate and expressive with respect to quantitative bisimulation

Weighted Modal Transition Systems

Specification theories as a tool in model-driven development processes of component-based software systems have recently attracted a considerable attention. Current specification theories are however qualitative in nature, and therefore fragile in the sense that the inevitable approximation of systems by models, combined with the fundamental unpredictability of hardware platforms, makes it difficult to transfer conclusions about the behavior, based on models, to the actual system. Hence this approach is arguably unsuited for modern software systems. We propose here the first specification theory which allows to capture quantitative aspects during the refinement and implementation process, thus leveraging the problems of the qualitative setting. Our proposed quantitative specification framework uses weighted modal transition systems as a formal model of specifications. These are labeled transition systems with the additional feature that they can model optional behavior which may or may not be implemented by the system. Satisfaction and refinement is lifted from the well-known qualitative to our quantitative setting, by introducing a notion of distances between weighted modal transition systems. We show that quantitative versions of parallel composition as well as quotient (the dual to parallel composition) inherit the properties from the Boolean setting.Comment: Submitted to Formal Methods in System Desig

The quantitative linear-time–branching-time spectrum

International audienceWe present a distance-agnostic approach to quantitative verification. Taking as input an unspecified distance on system traces, or executions, we develop a game-based framework which allows us to define a spectrum of different interesting system distances corresponding to the given trace distance. Thus we extend the classic linear-time–branching-time spectrum to a quantitative setting, parametrized by trace distance. We also provide fixed-point characterizations of all system distances, and we prove a general transfer principle which allows us to transfer counterexamples from the qualitative to the quantitative setting, showing that all system distances are mutually topologically inequivalent

Distances for Weighted Transition Systems: Games and Properties

We develop a general framework for reasoning about distances between transition systems with quantitative information. Taking as starting point an arbitrary distance on system traces, we show how this leads to natural definitions of a linear and a branching distance on states of such a transition system. We show that our framework generalizes and unifies a large variety of previously considered system distances, and we develop some general properties of our distances. We also show that if the trace distance admits a recursive characterization, then the corresponding branching distance can be obtained as a least fixed point to a similar recursive characterization. The central tool in our work is a theory of infinite path-building games with quantitative objectives.Comment: In Proceedings QAPL 2011, arXiv:1107.074

En ny agenda for entreprenørskabsforskningen:Dansk forskning i entreprenørielle muligheder

Hvad er en entreprenøriel mulighed? Og hvordan opstår den? Disse to spørgsmål er omdrejningspunkt for et af de centrale temaer i forskningen om entreprenørskab. I denne artikel redegøres for de danske bidrag til denne debat. Disse udgør samlet konturerne til en dansk agenda for entreprenørskabsforskning. Denne tager udgangspunkt i en antagelse om, at muligheder skabes i dynamiske sociale interaktioner. Endvidere redegøres for begrænsningerne og udfordringerne for den danske agenda.What is an entrepreneurial opportunity? And how does it arise? These two questions are at the core of one of the key issues in research on entrepreneurship. Taken together, the Danish contributions to this debate as presented in this article outline the contours of a Danish agenda for entrepreneurship research, based on the assumption that opportunities are created in dynamic social interactions. The limitations and challenges of the Danish agenda are also discussed

En ny agenda for entreprenørskabsforskningen: Dansk forskning i entreprenørielle muligheder

Hvad er en entreprenøriel mulighed? Og hvordan opstår den? Disse to spørgsmål er omdrejningspunkt for et af de centrale temaer i forskningen om entreprenørskab. I denne artikel redegøres for de danske bidrag til denne debat. Disse udgør samlet konturerne til en dansk agenda for entreprenørskabsforskning. Denne tager udgangspunkt i en antagelse om, at muligheder skabes i dynamiske sociale interaktioner. Endvidere redegøres for begrænsningerne og udfordringerne for den danske agenda.What is an entrepreneurial opportunity? And how does it arise? These two questions are at the core of one of the key issues in research on entrepreneurship. Taken together, the Danish contributions to this debate as presented in this article outline the contours of a Danish agenda for entrepreneurship research, based on the assumption that opportunities are created in dynamic social interactions. The limitations and challenges of the Danish agenda are also discussed

Safety and EEG data quality of concurrent high-density EEG and high-speed fMRI at 3 Tesla

Concurrent EEG and fMRI is increasingly used to characterize the spatial-temporal dynamics of brain activity. However, most studies to date have been limited to conventional echo-planar imaging (EPI). There is considerable interest in integrating recently developed high-speed fMRI methods with high-density EEG to increase temporal resolution and sensitivity for task-based and resting state fMRI, and for detecting interictal spikes in epilepsy. In the present study using concurrent high-density EEG and recently developed high-speed fMRI methods, we investigate safety of radiofrequency (RF) related heating, the effect of EEG on cortical signal-to-noise ratio (SNR) in fMRI, and assess EEG data quality.The study compared EPI, multi-echo EPI, multi-band EPI and multi-slab echo-volumar imaging pulse sequences, using clinical 3 Tesla MR scanners from two different vendors that were equipped with 64- and 256-channel MR-compatible EEG systems, respectively, and receive only array head coils. Data were collected in 11 healthy controls (3 males, age range 18-70 years) and 13 patients with epilepsy (8 males, age range 21-67 years). Three of the healthy controls were scanned with the 256-channel EEG system, the other subjects were scanned with the 64-channel EEG system. Scalp surface temperature, SNR in occipital cortex and head movement were measured with and without the EEG cap. The degree of artifacts and the ability to identify background activity was assessed by visual analysis by a trained expert in the 64 channel EEG data (7 healthy controls, 13 patients).RF induced heating at the surface of the EEG electrodes during a 30-minute scan period with stable temperature prior to scanning did not exceed 1.0° C with either EEG system and any of the pulse sequences used in this study. There was no significant decrease in cortical SNR due to the presence of the EEG cap (p > 0.05). No significant differences in the visually analyzed EEG data quality were found between EEG recorded during high-speed fMRI and during conventional EPI (p = 0.78). Residual ballistocardiographic artifacts resulted in 58% of EEG data being rated as poor quality.This study demonstrates that high-density EEG can be safely implemented in conjunction with high-speed fMRI and that high-speed fMRI does not adversely affect EEG data quality. However, the deterioration of the EEG quality due to residual ballistocardiographic artifacts remains a significant constraint for routine clinical applications of concurrent EEG-fMRI

A Quantitative Characterization of Weighted Kripke Structures in Temporal Logic

We extend the usual notion of Kripke Structures with a weighted transition relation, and generalize the usual Boolean satisfaction relation of CTL to a map which assigns to states and temporal formulae a real-valued distance describing the degree of satisfaction. We describe a general approach to obtaining quantitative interpretations for a generic extension of the CTL syntax, and show that, for one such interpretation, the logic is both adequate and expressive with respect to quantitative bisimulation