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Search Results: 1 - 10 of 1506 matches for " Marius Lewerenz "
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Quantum phases of a chain of strongly interacting anyons
Peter E. Finch,Holger Frahm,Marius Lewerenz,Ashley Milsted,Tobias J. Osborne
Physics , 2014, DOI: 10.1103/PhysRevB.90.081111
Abstract: We study a strongly interacting chain of anyons with fusion rules determined by SO(5)2. The phase portrait is identified with a combination of numerical and analytical techniques. Several critical phases with different central charges and their corresponding transitions identified.
Probing the structure and dynamics of molecular clusters using rotational wavepackets
Gediminas Galinis,Cephise Cacho,Richard T. Chapman,Andrew M. Ellis,Marius Lewerenz,Luis G. Mendoza Luna,Russell S. Minns,Mirjana Mladenovic,Arnaud Rouzée,Emma Springate,I. C. Edmond Turcu,Mark J. Watkins,Klaus von Haeften
Physics , 2014, DOI: 10.1103/PhysRevLett.113.043004
Abstract: The chemical and physical properties of molecular clusters can heavily depend on their size, which makes them very attractive for the design of new materials with tailored properties. Deriving the structure and dynamics of clusters is therefore of major interest in science. Weakly bound clusters can be studied using conventional spectroscopic techniques, but the number of lines observed is often too small for a comprehensive structural analysis. Impulsive alignment generates rotational wavepackets, which provides simultaneous information on structure and dynamics, as has been demonstrated successfully for isolated molecules. Here, we apply this technique for the firsttime to clusters comprising of a molecule and a single helium atom. By forcing the population of high rotational levels in intense laser fields we demonstrate the generation of rich rotational line spectra for this system, establishing the highly delocalised structure and the coherence of rotational wavepacket propagation. Our findings enable studies of clusters of different sizes and complexity as well as incipient superfluidity effects using wavepacket methods.
Exploring the Nature of Information Systems Development Methodology: A Synthesized View Based on a Literature Review  [PDF]
Daniela Mihailescu, Marius Mihailescu
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.32033
Abstract: New Information Systems Development Methodologies (ISDMs) are suggested in the belief that their deployment would be beneficial to consultants in their work. A large number of ISDMs already exist but their value has been questioned and at the same time new methodologies continue to be introduced in an attempt to support and improve the practice of information systems development work. What is not always clear from current studies is that ISDM is a multi-perspective and cross-discipline phenomenon. Although a large amount of knowledge of ISDM is available, different disciplinary interests have resulted in fragmented assessments of it. This paper intends to identify theoretical perspectives applied in the conceptualization of ISDM. A review of the literature on ISDM was conducted and four different theoretical perspectives were identified: 1) system, 2) structure, 3) innovation, and 4) knowledge. While each perspective provides various overarching depictions of ISDM, the synthesized view of ISDM provided in this study reveals the complexities and ambiguities of a multifaceted phenomenon such as ISDM. Suggestions for an alternative conceptualization of ISDM are provided in an attempt to facilitate the investigation of ISDM.
Quantum Tic-Tac-Toe: A Genuine Probabilistic Approach  [PDF]
Marius Nagy, Naya Nagy
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.331243
Abstract: We propose a quantum version of Tic-Tac-Toe which accurately reflects the inherent probabilistic nature of the measurement principle in quantum mechanics. We then formulate a quantum strategy which allows a quantum player to consistently win over a classical player, with a certain probability. This result can be seen as another proof of the superior computational power of a quantum system with respect to a classical one. Our investigation also reveals that the non-determinism and complexity introduced by the principles of quantum mechanics into even the most simple games make brute-force strategies considerably more difficult to implement. Consequently, games in which machines have gained the upper hand over humans may be made fair again by upgrading them to a quantum level.
On a Discrete Version of the Mohr-Mascheroni Theorem  [PDF]
Marius Munteanu, Laura Munteanu
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411A4002
Abstract:

We introduce a new geometric tool called n-compass and show that the famous theorem of Mascheroni and Mohr remains valid if the traditional compass is replaced by the newly introduced tool.

Rational Equiangular Polygons  [PDF]
Marius Munteanu, Laura Munteanu
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410197
Abstract:

The main purpose of this note is to investigate equiangular polygons with rational edges. When the number of edges is the power of a prime, we determine simple, necessary and sufficient conditions for the existence of such polygons. As special cases of our investigations, we settle two conjectures involving arithmetic polygons.

Fumaric Acid Esters Stimulate Astrocytic VEGF Expression through HIF-1α and Nrf2
Diana Wiesner, Irma Merdian, Jan Lewerenz, Albert C. Ludolph, Luc Dupuis, Anke Witting
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076670
Abstract: Fumaric acid esters (FAE) are oral analogs of fumarate that have recently been shown to decrease relapse rate and disease progression in multiple sclerosis (MS), prompting to investigate their protective potential in other neurological diseases such as amyotrophic lateral sclerosis (ALS). Despite efficacy in MS, mechanisms of action of FAEs are still largely unknown. FAEs are known to activate the transcription factor Nrf2 and downstream anti-oxidant responses through the succination of Nrf2 inhibitor KEAP1. However, fumarate is also a known inhibitor of prolyl-hydroxylases domain enzymes (PhD), and PhD inhibition might lead to stabilization of the HIF-1α transcription factor under normoxic conditions and subsequent activation of a pseudo hypoxic response. Whether Nrf2 activation is associated with HIF-1α stabilization in response to FAEs in cell types relevant to MS or ALS remains unknown. Here, we show that FAEs elicit HIF-1α accumulation, and VEGF release as its expected consequence, in astrocytes but not in other cell types of the central nervous system. Reporter assays demonstrated that increased astrocytic VEGF release in response to FAEs was dependent upon both HIF-1α and Nrf2 activation. Last, astrocytes of transgenic mice expressing SOD1(G93A), an animal model of ALS, displayed reduced VEGF release in response to FAEs. These studies show that FAEs elicit different signaling pathways in cell types from the central nervous system, in particular a pseudo-hypoxic response in astrocytes. Disease relevant mutations might affect this response.
Efficient Direct Solar-to-Hydrogen Conversion by In Situ Interface Transformation of a Tandem Structure
Matthias M. May,Hans-Joachim Lewerenz,David Lackner,Frank Dimroth,Thomas Hannappel
Physics , 2015, DOI: 10.1038/ncomms9286
Abstract: Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilises customised tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here, a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalisation procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.
Local exact controllability of the diffusion equation in one dimension
Marius Beceanu
Abstract and Applied Analysis , 2003, DOI: 10.1155/s1085337503303033
Abstract: This paper establishes the local exact null controllability of the diffusion equation in one dimension using distributed controls in the case of the Dirichlet boundary value problem. Most of the techniques used in the course of the proof are borrowed from Barbu (2002).
Dani l 2 as satire
Marius Nel
HTS Theological Studies/Teologiese Studies , 2012,
Abstract: Daniel 2 as satire. Readers use intuitive and acquired knowledge about genres in interpreting what they read and hear, underlining the importance of establishing the genre of a specific piece of literature. The genre of the tales in the Book of Daniel (1–6) has been researched over a long period, without leading to a consensus. In this article it is suggested that the genre of the tales in Daniel may be described in terms of satire, used as a means of resistance to foreign political oppression. Especially humor and irony are utilised in the satire to describe Jewish perception of the oppression and oppressor, and to make suggestions for acting in the crisis situation of Antiochus’ suppression of the Jewish religion. This is demonstrated in terms of the tale in Daniel 2, and specifically in the depiction of the indirect characters in the tale – the God of the Jews in Daniel 2, in contrast to the powerlessness of the gods of the mighty heathen king. In this way the true nature of Jewish oppression is pictured in a humorous way when the Babylonian gods are at the mercy of the Jewish God. HTS Teologiese Studies/Theological Studies, 68(1), 2012
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