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Search Results: 1 - 10 of 411772 matches for " Stephen M. Fuchs "
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Cooperation between Top-Down and Bottom-Up Theorem Provers
M. Fuchs,D. Fuchs
Computer Science , 2011, DOI: 10.1613/jair.573
Abstract: Top-down and bottom-up theorem proving approaches each have specific advantages and disadvantages. Bottom-up provers profit from strong redundancy control but suffer from the lack of goal-orientation, whereas top-down provers are goal-oriented but often have weak calculi when their proof lengths are considered. In order to integrate both approaches, we try to achieve cooperation between a top-down and a bottom-up prover in two different ways: The first technique aims at supporting a bottom-up with a top-down prover. A top-down prover generates subgoal clauses, they are then processed by a bottom-up prover. The second technique deals with the use of bottom-up generated lemmas in a top-down prover. We apply our concept to the areas of model elimination and superposition. We discuss the ability of our techniques to shorten proofs as well as to reorder the search space in an appropriate manner. Furthermore, in order to identify subgoal clauses and lemmas which are actually relevant for the proof task, we develop methods for a relevancy-based filtering. Experiments with the provers SETHEO and SPASS performed in the problem library TPTP reveal the high potential of our cooperation approaches.
The Ccr4-Not Complex Interacts with the mRNA Export Machinery
Shana C. Kerr,Nowel Azzouz,Stephen M. Fuchs,Martine A. Collart,Brian D. Strahl,Anita H. Corbett,R. Nicholas Laribee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018302
Abstract: The Ccr4-Not complex is a key eukaryotic regulator of gene transcription and cytoplasmic mRNA degradation. Whether this complex also affects aspects of post-transcriptional gene regulation, such as mRNA export, remains largely unexplored. Human Caf1 (hCaf1), a Ccr4-Not complex member, interacts with and regulates the arginine methyltransferase PRMT1, whose targets include RNA binding proteins involved in mRNA export. However, the functional significance of this regulation is poorly understood.
Mitigating mountain hazards in Austria – legislation, risk transfer, and awareness building
M. Holub,S. Fuchs
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2009,
Abstract: Embedded in the overall concept of integral risk management, mitigating mountain hazards is pillared by land use regulations, risk transfer, and information. In this paper aspects on legislation related to natural hazards in Austria are summarised, with a particular focus on spatial planning activities and hazard mapping, and possible adaptations focussing on enhanced resilience are outlined. Furthermore, the system of risk transfer is discussed, highlighting the importance of creating incentives for risk-aware behaviour, above all with respect to individual precaution and insurance solutions. Therefore, the issue of creating awareness through information is essential, which is presented subsequently. The study results in recommendations of how administrative units on different federal and local levels could increase the enforcement of regulations related to the minimisation of natural hazard risk. Moreover, the nexus to risk transfer mechanisms is provided, focusing on the current compensation system in Austria and some possible adjustments in order to provide economic incentives for (private) investments in mitigation measures, i.e. local structural protection. These incentives should be supported by delivering information on hazard and risk target-oriented to any stakeholder involved. Therefore, coping strategies have to be adjusted and the interaction between prevention and precaution has to be highlighted. The paper closes with recommendations of how these efforts could be achieved, with a particular focus on the situation in the Republic of Austria.
Equations of structural relaxation
M. Fuchs,Th. Voigtmann
Physics , 1999, DOI: 10.1080/014186399255917
Abstract: In the mode coupling theory of the liquid to glass transition the long time structural relaxation follows from equations solely determined by equilibrium structural parameters. The present extension of these structural relaxation equations to arbitrarily short times on the one hand allows calculations unaffected by model assumptions about the microscopic dynamics and on the other hand supplies new starting points for analytical studies. As a first application, power-law like structural relaxation at a glass-transition singularity is explicitly proven for a special schematic MCT model.
Nonergodicity transitions in colloidal suspensions with attractive interactions
J. Bergenholtz,M. Fuchs
Physics , 1999, DOI: 10.1103/PhysRevE.59.5706
Abstract: The colloidal gel and glass transitions are investigated using the idealized mode coupling theory (MCT) for model systems characterized by short-range attractive interactions. Results are presented for the adhesive hard sphere and hard core attractive Yukawa systems. According to MCT, the former system shows a critical glass transition concentration that increases significantly with introduction of a weak attraction. For the latter attractive Yukawa system, MCT predicts low temperature nonergodic states that extend to the critical and subcritical region. Several features of the MCT nonergodicity transition in this system agree qualitatively with experimental observations on the colloidal gel transition, suggesting that the gel transition is caused by a low temperature extension of the glass transition. The range of the attraction is shown to govern the way the glass transition line traverses the phase diagram relative to the critical point, analogous to findings for the fluid-solid freezing transition.
Flow curves of colloidal dispersions close to the glass transition: Asymptotic scaling laws in a schematic model of mode coupling theory
D. Hajnal,M. Fuchs
Physics , 2008, DOI: 10.1140/epje/i2008-10361-0
Abstract: The flow curves, viz. the curves of stationary stress under steady shearing, are obtained close to the glass transition in dense colloidal dispersions using asymptotic expansions in a schematic model of mode coupling theory. The shear thinning of the viscosity in fluid states and the yielding of glassy states is discussed. At the transition between fluid and shear-molten glass, simple and generalized Herschel-Bulkley laws are derived with power law exponents that can be computed for different particle interactions from the equilibrium structure factor.
Gel transitions in colloidal suspensions
J. Bergenholtz,M. Fuchs
Physics , 1999, DOI: 10.1088/0953-8984/11/50/310
Abstract: The idealized mode coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures MCT predicts a slowing down of the local dynamics and ergodicity breaking transitions. The nonergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the nonergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical nonergodicity parameters, motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low temperature MCT nonergodicity transitions.
Statistical mechanics derivation of hydrodynamic boundary conditions: the diffusion equation
M. Fuchs,K. Kroy
Physics , 2002, DOI: 10.1088/0953-8984/14/40/313
Abstract: Considering the example of interacting Brownian particles we present a linear response derivation of the boundary condition for the corresponding hydrodynamic description (the diffusion equation). This requires us to identify a non-analytic structure in a microscopic relaxation kernel connected to the frequency dependent penetration length familiar for diffusive processes, and leads to a microscopic definition of the position where the hydrodynamic boundary condition has to be applied. Corrections to the hydrodynamic limit are obtained and we derive general amplitudes of spatially and temporally long ranged states in the considered diffusive system.
Inter-molecular structure factors of macromolecules in solution: integral equation results
M. Fuchs,M. Müller
Physics , 1999, DOI: 10.1103/PhysRevE.60.1921
Abstract: The inter-molecular structure of semidilute polymer solutions is studied theoretically. The low density limit of a generalized Ornstein-Zernicke integral equation approach to polymeric liquids is considered. Scaling laws for the dilute-to-semidilute crossover of random phase (RPA) like structure are derived for the inter-molecular structure factor on large distances when inter-molecular excluded volume is incorporated at the microscopic level. This leads to a non-linear equation for the excluded volume interaction parameter. For macromolecular size-mass scaling exponents, $\nu$, above a spatial-dimension dependent value, $\nu_c=2/d$, mean field like density scaling is recovered, but for $\nu<\nu_c$ the density scaling becomes non-trivial in agreement with field theoretic results and justifying phenomenological extensions of RPA. The structure of the polymer mesh in semidilute solutions is discussed in detail and comparisons with large scale Monte Carlo simulations are added. Finally a new possibility to determine the correction to scaling exponent $\omega_{12}$ is suggested.
Personality Fit and Positive Interventions: Extraverted and Introverted Individuals Benefit from Different Happiness Increasing Strategies  [PDF]
Stephen M. Schueller
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.312A172
Abstract:

The current investigation examined if introverts and extraverts benefit differentially from specific positive psychology interventions. Across two studies participants completed various interventions: three good things, gratitude visit, savoring, signature strength, and active-constructive responding. In study 1, each participant (N = 150) completed 1 of the 5 interventions over a one-week period. All 5 interventions led to increases in happiness, t(144) = 3.80, p < .001, and reductions in depressive symptoms t(144) = 5.20, p <.001. Neither exercise was more beneficial overall. The results of an ANCOVA (with baseline levels as a covariate) found that the interaction term for extraversion and condition was at a trend level F(4, 139) = 2.36, p = .056 and planned contrast analyses supported a pattern of person-activity fit. Extraverts benefited more from the gratitude visit and savoring exercises, whereas introverts benefited more from the active-constructive responding, signature strength, and three good things exercises. In study 2, participants (N = 85) were assigned to one of three groups: the gratitude visit performed either in-person, over the phone, or via mail. Participants completed each exercise over a one-week period. No differential efficacy was found for the 3 interventions, F(1,

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