Radiative Corrections to Multi-Level Mollow-Type Spectra

This paper is concerned with two rather basic phenomena: the incoherent fluorescence spectrum of an atom driven by an intense laser field and the coupling of the atom to the (empty) modes of the radiation field. The sum of the many-photon processes gives rise to the inelastic part of the atomic fluorescence, which, for a two-level system, has a well-known characteristic three-peak structure known as the Mollow spectrum. From a theoretical point of view, the Mollow spectrum finds a natural interpretation in terms of transitions among laser-dressed states which are the energy eigenstates of a second-quantized two-level system strongly coupled to a driving laser field. As recently shown, the quasi-energies of the laser-dressed states receive radiative corrections which are nontrivially different from the results which one would expect from an investigation of the coupling of the bare states to the vacuum modes. In this article, we briefly review the basic elements required for the analysis of the dynamic radiative corrections, and we generalize the treatment of the radiative corrections to the incoherent part of the steady-state fluorescence to a three-level system consisting of 1S, 3P and 2S states.Comment: Dedicated to Prof. H. Walther on the occasion of his 70th birthda

The Lazy Flipper: MAP Inference in Higher-Order Graphical Models by Depth-limited Exhaustive Search

This article presents a new search algorithm for the NP-hard problem of optimizing functions of binary variables that decompose according to a graphical model. It can be applied to models of any order and structure. The main novelty is a technique to constrain the search space based on the topology of the model. When pursued to the full search depth, the algorithm is guaranteed to converge to a global optimum, passing through a series of monotonously improving local optima that are guaranteed to be optimal within a given and increasing Hamming distance. For a search depth of 1, it specializes to Iterated Conditional Modes. Between these extremes, a useful tradeoff between approximation quality and runtime is established. Experiments on models derived from both illustrative and real problems show that approximations found with limited search depth match or improve those obtained by state-of-the-art methods based on message passing and linear programming.Comment: C++ Source Code available from http://hci.iwr.uni-heidelberg.de/software.ph

POWERING UP COMPANIES\u27 CRYSTAL BALLS: ANALYSIS OF A MULTI-CASE STUDY TOWARDS MORE APPLICABLE ENVIRONMENTAL SCANNING SYSTEMS

The increasing volatility of their companies\u27 environment is a growing concern for executives. IS-based environmental scanning that complements the accounting information system domain can help to manage this challenge. A substantial body of knowledge on such information systems exists, but these concepts often go unused in practice. This article develops five design guidelines for environmental scanning systems that are more applicable than those outlined in previous research. In doing so, we first compile a set of requirements based on the principle of economic efficiency, and then use findings from the absorptive capacity theory to specify them. Challenging several implementations against these requirements in a multicase study generates findings that we synthesize into design guidelines. They address diverse areas: designing a more comprehensive model for information gathering, setting up a collective learning process for interpreting information, using IS to enable management techniques familiar to executives, designing processes for more interorganizational integration of environmental scanning systems, and accelerating prototyping

Endogenous glucagon-like peptide 1 controls endocrine pancreatic secretion and antro-pyloro-duodenal motility in humans

Background: Exogenous use of the intestinal hormone glucagon-like peptide 1 (GLP-1) lowers glycaemia by stimulation of insulin, inhibition of glucagon, and delay of gastric emptying.Aims: To assess the effects of endogenous GLP-1 on endocrine pancreatic secretion and antro-pyloro-duodenal motility by utilising the GLP-1 receptor antagonist exendin(9-39)amide (ex(9-39)NH2).Methods: Nine healthy volunteers underwent four experiments each. In two experiments with and without intravenous infusion of ex(9-39)NH2 300 pmol/kg/min, a fasting period was followed by intraduodenal glucose perfusion at 1 and 2.5 kcal/min, with the higher dose stimulating GLP-1 release. Antro-pyloro-duodenal motility was measured by perfusion manometry. To calculate the incretin effect (that is, the proportion of plasma insulin stimulated by intestinal hormones) the glycaemia observed during the luminal glucose experiments was mimicked using intravenous glucose in two further experiments.Results: Ex(9-39)NH2 significantly increased glycaemia during fasting and duodenal glucose. It diminished plasma insulin during duodenal glucose and significantly reduced the incretin effect by approximately 50%. Ex(9-39)NH2 raised plasma glucagon during fasting and abolished the decrease in glucagon at the high duodenal glucose load. Ex(9-39)NH2 markedly stimulated antroduodenal contractility. At low duodenal glucose it reduced the stimulation of tonic and phasic pyloric motility. At the high duodenal glucose load it abolished pyloric stimulation.Conclusions: Endogenous GLP-1 stimulates postprandial insulin release. The pancreatic \textgreeka cell is under the tonic inhibitory control of GLP-1 thereby suppressing postprandial glucagon. GLP-1 tonically inhibits antroduodenal motility and mediates the postprandial inhibition of antral and stimulation of pyloric motility. We therefore suggest GLP-1 as a true incretin hormone and enterogastrone in humans

Recent advances in hypertension and cardiovascular toxicities with vascular endothelial growth factor inhibition

No abstract available