Compact single-shot electro-optic detection system for THz pulses with femtosecond time resolution at MHz repetition rates

Electro-optical detection has proven to be a valuable technique to study temporal profiles of THz pulses with pulse durations down to femtoseconds. As the Coulomb field around a relativistic electron bunch resembles the current profile, electro-optical detection can be exploited for non-invasive bunch length measurements at accelerators. We have developed a very compact and robust electro-optical detection system based on spectral decoding for bunch length monitoring at the European XFEL with single-shot resolution better than 200~fs. Apart from the GaP crystal and the corresponding laser optics at the electron beamline, all components are housed in 19\" chassis for rack mount and remote operation inside the accelerator tunnel. An advanced laser synchronization scheme based on radio-frequency down-conversion has been developed for locking a custom-made Yb-fiber laser to the radio-frequency of the European XFEL accelerator. In order to cope with the high bunch repetition rate of the superconducting accelerator, a novel linear array detector (KALYPSO) has been employed for spectral measurements of the Yb-fiber laser pulses at frame rates of up to 2.26~MHz. In this paper, we describe all sub-systems of the electro-optical detection system as well as the measurement procedure in detail, and discuss first measurement results of longitudinal bunch profiles of around 400~fs (rms) with an arrival-time jitter of 35~fs (rms)

Geometric representations for minimalist grammars

We reformulate minimalist grammars as partial functions on term algebras for strings and trees. Using filler/role bindings and tensor product representations, we construct homomorphisms for these data structures into geometric vector spaces. We prove that the structure-building functions as well as simple processors for minimalist languages can be realized by piecewise linear operators in representation space. We also propose harmony, i.e. the distance of an intermediate processing step from the final well-formed state in representation space, as a measure of processing complexity. Finally, we illustrate our findings by means of two particular arithmetic and fractal representations.Comment: 43 pages, 4 figure

SAT-based Explicit LTL Reasoning

We present here a new explicit reasoning framework for linear temporal logic (LTL), which is built on top of propositional satisfiability (SAT) solving. As a proof-of-concept of this framework, we describe a new LTL satisfiability tool, Aalta\_v2.0, which is built on top of the MiniSAT SAT solver. We test the effectiveness of this approach by demonnstrating that Aalta\_v2.0 significantly outperforms all existing LTL satisfiability solvers. Furthermore, we show that the framework can be extended from propositional LTL to assertional LTL (where we allow theory atoms), by replacing MiniSAT with the Z3 SMT solver, and demonstrating that this can yield an exponential improvement in performance

The Price of Land and the Process of Expropriation

This paper applies a game theoretic model to situations in which the Dutch government expropriates land from some farmers in order to create a new public project. The model is a version of a finite period bargaining model with asymmetric information and one-sided offers. It is shown that the model can explain some casual observations as the fact that usually, but not always, the government and the farmers settle by agreement

The Tacrolimus Metabolism Rate Influences Renal Function after Kidney Transplantation

The effective calcineurin inhibitor (CNI) tacrolimus (Tac) is an integral part of the standard immunosuppressive regimen after renal transplantation (RTx). However, as a potent CNI it has nephrotoxic potential leading to impaired renal function in some cases. Therefore, it is of high clinical impact to identify factors which can predict who is endangered to develop CNI toxicity. We hypothesized that the Tac metabolism rate expressed as the blood concentration normalized by the dose (C/D ratio) is such a simple predictor. Therefore, we analyzed the impact of the C/D ratio on kidney function after RTx. Renal function was analyzed 1, 2, 3, 6, 12 and 24 months after RTx in 248 patients with an immunosuppressive regimen including basiliximab, tacrolimus, mycophenolate mofetil and prednisolone. According to keep the approach simple, patients were split into three C/D groups: fast, intermediate and slow metabolizers. Notably, compared with slow metabolizers fast metabolizers of Tac showed significantly lower estimated glomerular filtration rate (eGFR) values at all the time points analyzed. Moreover, fast metabolizers underwent more indication renal biopsies (p = 0.006) which revealed a higher incidence of CNI nephrotoxicity (p = 0.015) and BK nephropathy (p = 0.024) in this group. We herein identified the C/D ratio as an easy calculable risk factor for the development of CNI nephrotoxicity and BK nephropathy after RTx. We propose that the simple C/D ratio should be taken into account early in patient’s risk management strategies.</p

Set optimization - a rather short introduction

Recent developments in set optimization are surveyed and extended including various set relations as well as fundamental constructions of a convex analysis for set- and vector-valued functions, and duality for set optimization problems. Extensive sections with bibliographical comments summarize the state of the art. Applications to vector optimization and financial risk measures are discussed along with algorithmic approaches to set optimization problems

DecSerFlow: Towards a Truly Declarative Service Flow Language

The need for process support in the context of web services has triggered the development of many languages, systems, and standards. Industry has been developing software solutions and proposing standards such as BPEL, while researchers have been advocating the use of formal methods such as Petri nets and pi-calculus. The languages developed for service flows, i.e., process specification languages for web services, have adopted many concepts from classical workflow management systems. As a result, these languages are rather procedural and this does not fit well with the autonomous nature of services. Therefore, we propose DecSerFlow as a Declarative Service Flow Language. DecSerFlow can be used to specify, enact, and monitor service flows. The language is extendible (i.e., constructs can be added without changing the engine or semantical basis) and can be used to enforce or to check the conformance of service flows. Although the language has an appealing graphical representation, it is grounded in temporal logic

Photoabsorption and photoion spectroscopy of atomic uranium in the region of 6p and 5d excitations

The photoabsorption process in atomic uranium has been investigated experimentally and theoretically in the 15–150-eV region. Using the dual laser plasma technique, the 6p photoabsorption spectrum has been recorded while for the first time the 5d region has been remeasured photoelectrically using both photoabsorption and photoion spectroscopy. Interpretation of the photoabsorption spectra is supported by Hartree-Fock calculations which take into account spin-flip decay and the interaction of many discrete states with many continua. The 6p spectrum is entirely dominated by spin-orbit split 6p⃗6d transitions. The 5d-subshell photoabsorption is shown to consist predominantly of discrete 5d⃗5f excitations; here the electrostatic and spin-orbit interactions are comparable in strength

Component-wise incremental LTL model checking

Efficient symbolic and explicit-state model checking approaches have been developed for the verification of linear time temporal logic (LTL) properties. Several attempts have been made to combine the advantages of the various algorithms. Model checking LTL properties usually poses two challenges: one must compute the synchronous product of the state space and the automaton model of the desired property, then look for counterexamples that is reduced to finding strongly connected components (SCCs) in the state space of the product. In case of concurrent systems, where the phenomenon of state space explosion often prevents the successful verification, the so-called saturation algorithm has proved its efficiency in state space exploration. This paper proposes a new approach that leverages the saturation algorithm both as an iteration strategy constructing the product directly, as well as in a new fixed-point computation algorithm to find strongly connected components on-the-fly by incrementally processing the components of the model. Complementing the search for SCCs, explicit techniques and component-wise abstractions are used to prove the absence of counterexamples. The resulting on-the-fly, incremental LTL model checking algorithm proved to scale well with the size of models, as the evaluation on models of the Model Checking Contest suggests