26,226 research outputs found
A weakly universal cellular automaton in the pentagrid with five states
In this paper, we construct a cellular automaton on the pentagrid which is
planar, weakly universal and which have five states only. This result much
improves the best result which was with nine statesComment: 23 pages, 21 figure
Requirements Prioritization Based on Benefit and Cost Prediction: An Agenda for Future Research
In early phases of the software cycle, requirements
prioritization necessarily relies on the specified
requirements and on predictions of benefit and cost of
individual requirements. This paper presents results of
a systematic review of literature, which investigates
how existing methods approach the problem of
requirements prioritization based on benefit and cost.
From this review, it derives a set of under-researched
issues which warrant future efforts and sketches an
agenda for future research in this area
Requirements Prioritization Based on Benefit and Cost Prediction: A Method Classification Framework
In early phases of the software development process, requirements prioritization necessarily relies on the specified requirements and on predictions of benefit and cost of individual requirements. This paper induces a conceptual model of requirements prioritization based on benefit and cost. For this purpose, it uses Grounded Theory. We provide a detailed account of the procedures and rationale of (i) how we obtained our results and (ii) how we used them to form the basis for a framework for classifying requirements prioritization methods
SUSY-QCD Corrections to Dark Matter Annihilation in the Higgs Funnel
We compute the full O(alpha_s) SUSY-QCD corrections to dark matter
annihilation in the Higgs-funnel, resumming potentially large mu tan beta and
A_b contributions and keeping all finite O(m_b,s,1/tan^2 beta) terms. We
demonstrate numerically that these corrections strongly influence the
extraction of SUSY mass parameters from cosmological data and must therefore be
included in common analysis tools such as DarkSUSY or micrOMEGAs.Comment: 4 pages, 3 (partly color) figures, version to be published in PR
Cardiotoxicity with vascular endothelial growth factor inhibitor therapy
Angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway (VSP) have been important additions in the therapy of various cancers, especially renal cell carcinoma and colorectal cancer. Bevazicumab, the first VSP to receive FDA approval in 2004 targeting all circulating isoforms of VEGF-A, has become one of the best-selling drugs of all times. The second wave of tyrosine kinase inhibitors (TKIs), which target the intracellular site of VEGF receptor kinases, began with the approval of sorafenib in 2005 and sunitinib in 2006. Heart failure was subsequently noted, in 2–4% of patients on bevacizumab and in 3–8% of patients on VSP-TKIs. The very fact that the single-targeted monoclonal antibody bevacizumab can induce cardiotoxicity supports a pathomechanistic role for the VSP and the postulate of the “vascular” nature of VSP inhibitor cardiotoxicity. In this review we will outline this scenario in greater detail, reflecting on hypertension and coronary artery disease as risk factors for VSP inhibitor cardiotoxicity, but also similarities with peripartum and diabetic cardiomyopathy. This leads to the concept that any preexisting or coexisting condition that reduces the vascular reserve or utilizes the vascular reserve for compensatory purposes may pose a risk factor for cardiotoxicity with VSP inhibitors. These conditions need to be carefully considered in cancer patients who are to undergo VSP inhibitor therapy. Such vigilance is not to exclude patients from such prognostically extremely important therapy but to understand the continuum and to recognize and react to any cardiotoxicity dynamics early on for superior overall outcomes
Neural network modeling of memory deterioration in Alzheimer's disease
The clinical course of Alzheimer's disease (AD) is generally characterized by progressive gradual deterioration, although large clinical variability exists. Motivated by the recent quantitative reports of synaptic changes in AD, we use a neural network model to investigate how the interplay between synaptic deletion and compensation determines the pattern of memory deterioration, a clinical hallmark of AD. Within the model we show that the deterioration of memory retrieval due to synaptic deletion can be much delayed by multiplying all the remaining synaptic weights by a common factor, which keeps the average input to each neuron at the same level. This parallels the experimental observation that the total synaptic area per unit volume (TSA) is initially preserved when synaptic deletion occurs. By using different dependencies of the compensatory factor on the amount of synaptic deletion one can define various compensation strategies, which can account for the observed variation in the severity and progression rate of AD
Flavour Violation in Gauge-Mediated Supersymmetry Breaking Models: Experimental Constraints and Phenomenology at the LHC
We present an extensive analysis of gauge-mediated supersymmetry breaking
models with minimal and non-minimal flavour violation. We first demonstrate
that low-energy, precision electroweak, and cosmological constraints exclude
large "collider-friendly" regions of the minimal parameter space. We then
discuss various possibilities how flavour violation, although naturally
suppressed, may still occur in gauge-mediation models. The introduction of
non-minimal flavour violation at the electroweak scale is shown to relax the
stringent experimental constraints, so that benchmark points, that are also
cosmologically viable, can be defined and their phenomenology, i.e. squark and
gaugino production cross sections with flavour violation, at the LHC can be
studied.Comment: 29 pages, 1 table, 27 figures. Minor changes. Version published in
Nucl. Phys.
Optimization of alloy-analogy-based approaches to the infinite-dimensional Hubbard model
An analytical expression for the self-energy of the infinite-dimensional
Hubbard model is proposed that interpolates between different exactly solvable
limits. We profit by the combination of two recent approaches that are based on
the alloy-analogy (Hubbard-III) solution: The modified alloy-analogy (MAA)
which focuses on the strong-coupling regime, and the Edwards-Hertz approach
(EHA) which correctly recovers the weak-coupling regime. Investigating the
high-energy expansion of the EHA self-energy, it turns out that the EHA
reproduces the first three exactly known moments of the spectral density only.
This may be insufficient for the investigation of spontaneous magnetism. The
analysis of the high-energy behavior of the CPA self-consistency equation
allows for a new interpretation of the MAA: The MAA is the only (two-component)
alloy-analogy that correctly takes into account the first four moments of the
spectral density. For small U, however, the MAA does not reproduce Fermi-liquid
properties. The defects of the MAA as well as of the EHA are avoided in the new
approach. We discuss the prospects of the theory and present numerical results
in comparison with essentially exact quantum Monte Carlo data. The correct
high-energy behavior of the self-energy is proved to be a decisive ingredient
for a reliable description of spontaneous magnetism.Comment: LaTeX, 18 pages, 12 eps figures include
Segregation in a fluidized binary granular mixture: Competition between buoyancy and geometric forces
Starting from the hydrodynamic equations of binary granular mixtures, we
derive an evolution equation for the relative velocity of the intruders, which
is shown to be coupled to the inertia of the smaller particles. The onset of
Brazil-nut segregation is explained as a competition between the buoyancy and
geometric forces: the Archimedean buoyancy force, a buoyancy force due to the
difference between the energies of two granular species, and two geometric
forces, one compressive and the other-one tensile in nature, due to the
size-difference. We show that inelastic dissipation strongly affects the phase
diagram of the Brazil nut phenomenon and our model is able to explain the
experimental results of Breu et al. (PRL, 2003, vol. 90, p. 01402).Comment: 5 pages, 2 figure
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